Template Designer Documentation — Jinja Documentation (3.0.x) (2024)

This document describes the syntax and semantics of the template engine andwill be most useful as reference to those creating Jinja templates. As thetemplate engine is very flexible, the configuration from the application canbe slightly different from the code presented here in terms of delimiters andbehavior of undefined values.

Synopsis¶

A Jinja template is simply a text file. Jinja can generate any text-basedformat (HTML, XML, CSV, LaTeX, etc.). A Jinja template doesn’t need to have aspecific extension: .html, .xml, or any other extension is just fine.

A template contains variables and/or expressions, which get replacedwith values when a template is rendered; and tags, which control thelogic of the template. The template syntax is heavily inspired by Django andPython.

Below is a minimal template that illustrates a few basics using the defaultJinja configuration. We will cover the details later in this document:

<!DOCTYPE html><html lang="en"><head> <title>My Webpage</title></head><body> <ul id="navigation"> {% for item in navigation %} <li><a href="{{ item.href }}">{{ item.caption }}</a></li> {% endfor %} </ul> <h1>My Webpage</h1> {{ a_variable }} {# a comment #}</body></html>

The following example shows the default configuration settings. An applicationdeveloper can change the syntax configuration from {% foo %} to <% foo%>, or something similar.

There are a few kinds of delimiters. The default Jinja delimiters areconfigured as follows:

{% ... %} for Statements
{{ ... }} for Expressions to print to the template output
{# ... #} for Comments not included in the template output

Line Statements and Comments are also possible,though they don’t have default prefix characters. To use them, setline_statement_prefix and line_comment_prefix when creating theEnvironment.

Template File Extension¶

As stated above, any file can be loaded as a template, regardless offile extension. Adding a .jinja extension, like user.html.jinjamay make it easier for some IDEs or editor plugins, but is not required.Autoescaping, introduced later, can be applied based on file extension,so you’ll need to take the extra suffix into account in that case.

Another good heuristic for identifying templates is that they are in atemplates folder, regardless of extension. This is a common layoutfor projects.

Variables¶

Template variables are defined by the context dictionary passed to thetemplate.

You can mess around with the variables in templates provided they are passed inby the application. Variables may have attributes or elements on them you canaccess too. What attributes a variable has depends heavily on the applicationproviding that variable.

You can use a dot (.) to access attributes of a variable in additionto the standard Python __getitem__ “subscript” syntax ([]).

The following lines do the same thing:

{{ foo.bar }}{{ foo['bar'] }}

It’s important to know that the outer double-curly braces are not part of thevariable, but the print statement. If you access variables inside tags don’tput the braces around them.

If a variable or attribute does not exist, you will get back an undefinedvalue. What you can do with that kind of value depends on the applicationconfiguration: the default behavior is to evaluate to an empty string ifprinted or iterated over, and to fail for every other operation.

Implementation

For the sake of convenience, foo.bar in Jinja does the followingthings on the Python layer:

check for an attribute called bar on foo(getattr(foo, 'bar'))
if there is not, check for an item 'bar' in foo(foo.__getitem__('bar'))
if there is not, return an undefined object.

foo['bar'] works mostly the same with a small difference in sequence:

check for an item 'bar' in foo.(foo.__getitem__('bar'))
if there is not, check for an attribute called bar on foo.(getattr(foo, 'bar'))
if there is not, return an undefined object.

This is important if an object has an item and attribute with the samename. Additionally, the attr() filter only looks up attributes.

Filters¶

Variables can be modified by filters. Filters are separated from thevariable by a pipe symbol (|) and may have optional arguments inparentheses. Multiple filters can be chained. The output of one filter isapplied to the next.

For example, {{ name|striptags|title }} will remove all HTML Tags fromvariable name and title-case the output (title(striptags(name))).

Filters that accept arguments have parentheses around the arguments, just likea function call. For example: {{ listx|join(', ') }} will join a list withcommas (str.join(', ', listx)).

The List of Builtin Filters below describes all the builtin filters.

Tests¶

Beside filters, there are also so-called “tests” available. Tests can be usedto test a variable against a common expression. To test a variable orexpression, you add is plus the name of the test after the variable. Forexample, to find out if a variable is defined, you can do name is defined,which will then return true or false depending on whether name is definedin the current template context.

Tests can accept arguments, too. If the test only takes one argument, you canleave out the parentheses. For example, the following twoexpressions do the same thing:

{% if loop.index is divisibleby 3 %}{% if loop.index is divisibleby(3) %}

The List of Builtin Tests below describes all the builtin tests.

Comments¶

To comment-out part of a line in a template, use the comment syntax which isby default set to {# ... #}. This is useful to comment out parts of thetemplate for debugging or to add information for other template designers oryourself:

{# note: commented-out template because we no longer use this {% for user in users %} ... {% endfor %}#}

Whitespace Control¶

In the default configuration:

a single trailing newline is stripped if present
other whitespace (spaces, tabs, newlines etc.) is returned unchanged

If an application configures Jinja to trim_blocks, the first newline after atemplate tag is removed automatically (like in PHP). The lstrip_blocksoption can also be set to strip tabs and spaces from the beginning of aline to the start of a block. (Nothing will be stripped if there areother characters before the start of the block.)

With both trim_blocks and lstrip_blocks enabled, you can put block tagson their own lines, and the entire block line will be removed whenrendered, preserving the whitespace of the contents. For example,without the trim_blocks and lstrip_blocks options, this template:

<div> {% if True %} yay {% endif %}</div>

gets rendered with blank lines inside the div:

<div> yay</div>

But with both trim_blocks and lstrip_blocks enabled, the template blocklines are removed and other whitespace is preserved:

<div> yay</div>

You can manually disable the lstrip_blocks behavior by putting aplus sign (+) at the start of a block:

<div> {%+ if something %}yay{% endif %}</div>

Similarly, you can manually disable the trim_blocks behavior byputting a plus sign (+) at the end of a block:

<div> {% if something +%} yay {% endif %}</div>

You can also strip whitespace in templates by hand. If you add a minussign (-) to the start or end of a block (e.g. a For tag), acomment, or a variable expression, the whitespaces before or afterthat block will be removed:

{% for item in seq -%} {{ item }}{%- endfor %}

This will yield all elements without whitespace between them. If seq wasa list of numbers from 1 to 9, the output would be 123456789.

If Line Statements are enabled, they strip leading whitespaceautomatically up to the beginning of the line.

By default, Jinja also removes trailing newlines. To keep singletrailing newlines, configure Jinja to keep_trailing_newline.

Note

You must not add whitespace between the tag and the minus sign.

valid:

{%- if foo -%}...{% endif %}

invalid:

{% - if foo - %}...{% endif %}

Escaping¶

It is sometimes desirable – even necessary – to have Jinja ignore partsit would otherwise handle as variables or blocks. For example, if, withthe default syntax, you want to use {{ as a raw string in a template andnot start a variable, you have to use a trick.

The easiest way to output a literal variable delimiter ({{) is by using avariable expression:

{{ '{{' }}

For bigger sections, it makes sense to mark a block raw. For example, toinclude example Jinja syntax in a template, you can use this snippet:

{% raw %} <ul> {% for item in seq %} <li>{{ item }}</li> {% endfor %} </ul>{% endraw %}

Note

Minus sign at the end of {% raw -%} tag cleans all the spaces and newlinespreceding the first character of your raw data.

Line Statements¶

If line statements are enabled by the application, it’s possible to mark aline as a statement. For example, if the line statement prefix is configuredto #, the following two examples are equivalent:

<ul># for item in seq <li>{{ item }}</li># endfor</ul><ul>{% for item in seq %} <li>{{ item }}</li>{% endfor %}</ul>

The line statement prefix can appear anywhere on the line as long as no textprecedes it. For better readability, statements that start a block (such asfor, if, elif etc.) may end with a colon:

# for item in seq: ...# endfor

Note

Line statements can span multiple lines if there are open parentheses,braces or brackets:

<ul># for href, caption in [('index.html', 'Index'), ('about.html', 'About')]: <li><a href="{{ href }}">{{ caption }}</a></li># endfor</ul>

Since Jinja 2.2, line-based comments are available as well. For example, ifthe line-comment prefix is configured to be ##, everything from ## tothe end of the line is ignored (excluding the newline sign):

# for item in seq: <li>{{ item }}</li> ## this comment is ignored# endfor

Template Inheritance¶

The most powerful part of Jinja is template inheritance. Template inheritanceallows you to build a base “skeleton” template that contains all the commonelements of your site and defines blocks that child templates can override.

Sounds complicated but is very basic. It’s easiest to understand it by startingwith an example.

Base Template¶

This template, which we’ll call base.html, defines a simple HTML skeletondocument that you might use for a simple two-column page. It’s the job of“child” templates to fill the empty blocks with content:

<!DOCTYPE html><html lang="en"><head> {% block head %} <link rel="stylesheet" href="style.css" /> <title>{% block title %}{% endblock %} - My Webpage</title> {% endblock %}</head><body> <div id="content">{% block content %}{% endblock %}</div> <div id="footer"> {% block footer %} &copy; Copyright 2008 by <a href="http://domain.invalid/">you</a>. {% endblock %} </div></body></html>

In this example, the {% block %} tags define four blocks that child templatescan fill in. All the block tag does is tell the template engine that achild template may override those placeholders in the template.

block tags can be inside other blocks such as if, but they willalways be executed regardless of if the if block is actuallyrendered.

Child Template¶

A child template might look like this:

{% extends "base.html" %}{% block title %}Index{% endblock %}{% block head %} {{ super() }} <style type="text/css"> .important { color: #336699; } </style>{% endblock %}{% block content %} <h1>Index</h1> <p class="important"> Welcome to my awesome homepage. </p>{% endblock %}

The {% extends %} tag is the key here. It tells the template engine thatthis template “extends” another template. When the template system evaluatesthis template, it first locates the parent. The extends tag should be thefirst tag in the template. Everything before it is printed out normally andmay cause confusion. For details about this behavior and how to takeadvantage of it, see Null-Default Fallback. Also a block will always befilled in regardless of whether the surrounding condition is evaluated to be trueor false.

The filename of the template depends on the template loader. For example, theFileSystemLoader allows you to access other templates by giving thefilename. You can access templates in subdirectories with a slash:

{% extends "layout/default.html" %}

But this behavior can depend on the application embedding Jinja. Note thatsince the child template doesn’t define the footer block, the value fromthe parent template is used instead.

You can’t define multiple {% block %} tags with the same name in thesame template. This limitation exists because a block tag works in “both”directions. That is, a block tag doesn’t just provide a placeholder to fill- it also defines the content that fills the placeholder in the parent.If there were two similarly-named {% block %} tags in a template,that template’s parent wouldn’t know which one of the blocks’ content to use.

If you want to print a block multiple times, you can, however, use the specialself variable and call the block with that name:

<title>{% block title %}{% endblock %}</title><h1>{{ self.title() }}</h1>{% block body %}{% endblock %}

Super Blocks¶

It’s possible to render the contents of the parent block by calling super().This gives back the results of the parent block:

{% block sidebar %} <h3>Table Of Contents</h3> ... {{ super() }}{% endblock %}

Nesting extends¶

In the case of multiple levels of {% extends %},super references may be chained (as in super.super())to skip levels in the inheritance tree.

For example:

# parent.tmplbody: {% block body %}Hi from parent.{% endblock %}# child.tmpl{% extends "parent.tmpl" %}{% block body %}Hi from child. {{ super() }}{% endblock %}# grandchild1.tmpl{% extends "child.tmpl" %}{% block body %}Hi from grandchild1.{% endblock %}# grandchild2.tmpl{% extends "child.tmpl" %}{% block body %}Hi from grandchild2. {{ super.super() }} {% endblock %}

Rendering child.tmpl will givebody: Hi from child. Hi from parent.

Rendering grandchild1.tmpl will givebody: Hi from grandchild1.

Rendering grandchild2.tmpl will givebody: Hi from grandchild2. Hi from parent.

Named Block End-Tags¶

Jinja allows you to put the name of the block after the end tag for betterreadability:

{% block sidebar %} {% block inner_sidebar %} ... {% endblock inner_sidebar %}{% endblock sidebar %}

However, the name after the endblock word must match the block name.

Block Nesting and Scope¶

Blocks can be nested for more complex layouts. However, per default blocksmay not access variables from outer scopes:

{% for item in seq %} <li>{% block loop_item %}{{ item }}{% endblock %}</li>{% endfor %}

This example would output empty <li> items because item is unavailableinside the block. The reason for this is that if the block is replaced bya child template, a variable would appear that was not defined in the block orpassed to the context.

Starting with Jinja 2.2, you can explicitly specify that variables areavailable in a block by setting the block to “scoped” by adding the scopedmodifier to a block declaration:

{% for item in seq %} <li>{% block loop_item scoped %}{{ item }}{% endblock %}</li>{% endfor %}

When overriding a block, the scoped modifier does not have to be provided.

Required Blocks¶

Blocks can be marked as required. They must be overridden at somepoint, but not necessarily by the direct child template. Required blocksmay only contain space and comments, and they cannot be rendereddirectly.

page.txt¶

{% block body required %}{% endblock %}

issue.txt¶

{% extends "page.txt" %}

bug_report.txt¶

{% extends "issue.txt" %}{% block body %}Provide steps to demonstrate the bug.{% endblock %}

Rendering page.txt or issue.txt will raiseTemplateRuntimeError because they don’t override the body block.Rendering bug_report.txt will succeed because it does override theblock.

When combined with scoped, the required modifier must be placedafter the scoped modifier. Here are some valid examples:

{% block body scoped %}{% endblock %}{% block body required %}{% endblock %}{% block body scoped required %}{% endblock %}

Template Objects¶

extends, include, and import can take a template objectinstead of the name of a template to load. This could be useful in someadvanced situations, since you can use Python code to load a templatefirst and pass it in to render.

if debug_mode: layout = env.get_template("debug_layout.html")else: layout = env.get_template("layout.html")user_detail = env.get_template("user/detail.html", layout=layout)

{% extends layout %}

Note how extends is passed the variable with the template objectthat was passed to render, instead of a string.

HTML Escaping¶

When generating HTML from templates, there’s always a risk that a variable willinclude characters that affect the resulting HTML. There are two approaches:

manually escaping each variable; or
automatically escaping everything by default.

Jinja supports both. What is used depends on the application configuration.The default configuration is no automatic escaping; for various reasons:

Escaping everything except for safe values will also mean that Jinja isescaping variables known to not include HTML (e.g. numbers, booleans)which can be a huge performance hit.
The information about the safety of a variable is very fragile. It couldhappen that by coercing safe and unsafe values, the return value isdouble-escaped HTML.

Working with Manual Escaping¶

If manual escaping is enabled, it’s your responsibility to escapevariables if needed. What to escape? If you have a variable that mayinclude any of the following chars (>, <, &, or ") youSHOULD escape it unless the variable contains well-formed and trustedHTML. Escaping works by piping the variable through the |e filter:

{{ user.username|e }}

Working with Automatic Escaping¶

When automatic escaping is enabled, everything is escaped by default exceptfor values explicitly marked as safe. Variables and expressionscan be marked as safe either in:

The context dictionary by the application withmarkupsafe.Markup
The template, with the |safe filter.

If a string that you marked safe is passed through other Python codethat doesn’t understand that mark, it may get lost. Be aware of whenyour data is marked safe and how it is processed before arriving at thetemplate.

If a value has been escaped but is not marked safe, auto-escaping willstill take place and result in double-escaped characters. If you knowyou have data that is already safe but not marked, be sure to wrap it inMarkup or use the |safe filter.

Jinja functions (macros, super, self.BLOCKNAME) always return templatedata that is marked as safe.

String literals in templates with automatic escaping are consideredunsafe because native Python strings are not safe.

List of Control Structures¶

A control structure refers to all those things that control the flow of aprogram - conditionals (i.e. if/elif/else), for-loops, as well as things likemacros and blocks. With the default syntax, control structures appear inside{% ... %} blocks.

For¶

Loop over each item in a sequence. For example, to display a list of usersprovided in a variable called users:

<h1>Members</h1><ul>{% for user in users %} <li>{{ user.username|e }}</li>{% endfor %}</ul>

As variables in templates retain their object properties, it is possible toiterate over containers like dict:

<dl>{% for key, value in my_dict.items() %} <dt>{{ key|e }}</dt> <dd>{{ value|e }}</dd>{% endfor %}</dl>

Python dicts may not be in the order you want to display them in. Iforder matters, use the |dictsort filter.

<dl>{% for key, value in my_dict | dictsort %} <dt>{{ key|e }}</dt> <dd>{{ value|e }}</dd>{% endfor %}</dl>

Variable	Description
loop.index	The current iteration of the loop. (1 indexed)
loop.index0	The current iteration of the loop. (0 indexed)
loop.revindex	The number of iterations from the end of the loop(1 indexed)
loop.revindex0	The number of iterations from the end of the loop(0 indexed)
loop.first	True if first iteration.
loop.last	True if last iteration.
loop.length	The number of items in the sequence.
loop.cycle	A helper function to cycle between a list ofsequences. See the explanation below.
loop.depth	Indicates how deep in a recursive loopthe rendering currently is. Starts at level 1
loop.depth0	Indicates how deep in a recursive loopthe rendering currently is. Starts at level 0
loop.previtem	The item from the previous iteration of the loop.Undefined during the first iteration.
loop.nextitem	The item from the following iteration of the loop.Undefined during the last iteration.
loop.changed(*val)	True if previously called with a different value(or not called at all).

If¶

The if statement in Jinja is comparable with the Python if statement.In the simplest form, you can use it to test if a variable is defined, notempty and not false:

{% if users %}<ul>{% for user in users %} <li>{{ user.username|e }}</li>{% endfor %}</ul>{% endif %}

For multiple branches, elif and else can be used like in Python. You canuse more complex Expressions there, too:

{% if kenny.sick %} Kenny is sick.{% elif kenny.dead %} You killed Kenny! You bastard!!!{% else %} Kenny looks okay --- so far{% endif %}

If can also be used as an inline expression and forloop filtering.

Macros¶

Macros are comparable with functions in regular programming languages. Theyare useful to put often used idioms into reusable functions to not repeatyourself (“DRY”).

Here’s a small example of a macro that renders a form element:

{% macro input(name, value='', type='text', size=20) -%} <input type="{{ type }}" name="{{ name }}" value="{{ value|e }}" size="{{ size }}">{%- endmacro %}

The macro can then be called like a function in the namespace:

<p>{{ input('username') }}</p><p>{{ input('password', type='password') }}</p>

If the macro was defined in a different template, you have toimport it first.

Inside macros, you have access to three special variables:

varargs: If more positional arguments are passed to the macro than accepted by themacro, they end up in the special varargs variable as a list of values.
kwargs: Like varargs but for keyword arguments. All unconsumed keywordarguments are stored in this special variable.
caller: If the macro was called from a call tag, the caller is storedin this variable as a callable macro.

Macros also expose some of their internal details. The following attributesare available on a macro object:

name: The name of the macro. {{ input.name }} will print input.
arguments: A tuple of the names of arguments the macro accepts.
catch_kwargs: This is true if the macro accepts extra keyword arguments (i.e.: accessesthe special kwargs variable).
catch_varargs: This is true if the macro accepts extra positional arguments (i.e.:accesses the special varargs variable).
caller: This is true if the macro accesses the special caller variable and maybe called from a call tag.

If a macro name starts with an underscore, it’s not exported and can’tbe imported.

Call¶

In some cases it can be useful to pass a macro to another macro. For thispurpose, you can use the special call block. The following example showsa macro that takes advantage of the call functionality and how it can beused:

{% macro render_dialog(title, class='dialog') -%} <div class="{{ class }}"> <h2>{{ title }}</h2> <div class="contents"> {{ caller() }} </div> </div>{%- endmacro %}{% call render_dialog('Hello World') %} This is a simple dialog rendered by using a macro and a call block.{% endcall %}

It’s also possible to pass arguments back to the call block. This makes ituseful as a replacement for loops. Generally speaking, a call block worksexactly like a macro without a name.

Here’s an example of how a call block can be used with arguments:

{% macro dump_users(users) -%} <ul> {%- for user in users %} <li><p>{{ user.username|e }}</p>{{ caller(user) }}</li> {%- endfor %} </ul>{%- endmacro %}{% call(user) dump_users(list_of_user) %} <dl> <dt>Realname</dt> <dd>{{ user.realname|e }}</dd> <dt>Description</dt> <dd>{{ user.description }}</dd> </dl>{% endcall %}

Filters¶

Filter sections allow you to apply regular Jinja filters on a block oftemplate data. Just wrap the code in the special filter section:

{% filter upper %} This text becomes uppercase{% endfilter %}

Assignments¶

Inside code blocks, you can also assign values to variables. Assignments attop level (outside of blocks, macros or loops) are exported from the templatelike top level macros and can be imported by other templates.

Assignments use the set tag and can have multiple targets:

{% set navigation = [('index.html', 'Index'), ('about.html', 'About')] %}{% set key, value = call_something() %}

Scoping Behavior

Please keep in mind that it is not possible to set variables inside ablock and have them show up outside of it. This also applies toloops. The only exception to that rule are if statements which do notintroduce a scope. As a result the following template is not goingto do what you might expect:

{% set iterated = false %}{% for item in seq %} {{ item }} {% set iterated = true %}{% endfor %}{% if not iterated %} did not iterate {% endif %}

It is not possible with Jinja syntax to do this. Instead usealternative constructs like the loop else block or the special loopvariable:

{% for item in seq %} {{ item }}{% else %} did not iterate{% endfor %}

As of version 2.10 more complex use cases can be handled using namespaceobjects which allow propagating of changes across scopes:

{% set ns = namespace(found=false) %}{% for item in items %} {% if item.check_something() %} {% set ns.found = true %} {% endif %} * {{ item.title }}{% endfor %}Found item having something: {{ ns.found }}

Note that the obj.attr notation in the set tag is only allowed fornamespace objects; attempting to assign an attribute on any other objectwill raise an exception.

Changelog

New in version 2.10: Added support for namespace objects

Block Assignments¶

Changelog

New in version 2.8.

Starting with Jinja 2.8, it’s possible to also use block assignments tocapture the contents of a block into a variable name. This can be usefulin some situations as an alternative for macros. In that case, instead ofusing an equals sign and a value, you just write the variable name and theneverything until {% endset %} is captured.

Example:

{% set navigation %} <li><a href="/">Index</a> <li><a href="/downloads">Downloads</a>{% endset %}

The navigation variable then contains the navigation HTML source.

Changelog

Changed in version 2.10.

Starting with Jinja 2.10, the block assignment supports filters.

Example:

{% set reply | wordwrap %} You wrote: {{ message }}{% endset %}

Extends¶

The extends tag can be used to extend one template from another. You canhave multiple extends tags in a file, but only one of them may be executed ata time.

See the section about Template Inheritance above.

Blocks¶

Blocks are used for inheritance and act as both placeholders and replacementsat the same time. They are documented in detail in theTemplate Inheritance section.

Include¶

The include tag is useful to include a template and return therendered contents of that file into the current namespace:

{% include 'header.html' %} Body{% include 'footer.html' %}

Included templates have access to the variables of the active context bydefault. For more details about context behavior of imports and includes,see Import Context Behavior.

From Jinja 2.2 onwards, you can mark an include with ignore missing; inwhich case Jinja will ignore the statement if the template to be includeddoes not exist. When combined with with or without context, it mustbe placed before the context visibility statement. Here are some validexamples:

{% include "sidebar.html" ignore missing %}{% include "sidebar.html" ignore missing with context %}{% include "sidebar.html" ignore missing without context %}

Changelog

New in version 2.2.

You can also provide a list of templates that are checked for existencebefore inclusion. The first template that exists will be included. Ifignore missing is given, it will fall back to rendering nothing ifnone of the templates exist, otherwise it will raise an exception.

Example:

{% include ['page_detailed.html', 'page.html'] %}{% include ['special_sidebar.html', 'sidebar.html'] ignore missing %}

Changelog

Changed in version 2.4: If a template object was passed to the template context, you caninclude that object using include.

Import¶

Jinja supports putting often used code into macros. These macros can go intodifferent templates and get imported from there. This works similarly to theimport statements in Python. It’s important to know that imports are cachedand imported templates don’t have access to the current template variables,just the globals by default. For more details about context behavior ofimports and includes, see Import Context Behavior.

There are two ways to import templates. You can import a complete templateinto a variable or request specific macros / exported variables from it.

Imagine we have a helper module that renders forms (called forms.html):

{% macro input(name, value='', type='text') -%} <input type="{{ type }}" value="{{ value|e }}" name="{{ name }}">{%- endmacro %}{%- macro textarea(name, value='', rows=10, cols=40) -%} <textarea name="{{ name }}" rows="{{ rows }}" cols="{{ cols }}">{{ value|e }}</textarea>{%- endmacro %}

The easiest and most flexible way to access a template’s variablesand macros is to import the whole template module into a variable.That way, you can access the attributes:

{% import 'forms.html' as forms %}<dl> <dt>Username</dt> <dd>{{ forms.input('username') }}</dd> <dt>Password</dt> <dd>{{ forms.input('password', type='password') }}</dd></dl><p>{{ forms.textarea('comment') }}</p>

Alternatively, you can import specific names from a template into the currentnamespace:

{% from 'forms.html' import input as input_field, textarea %}<dl> <dt>Username</dt> <dd>{{ input_field('username') }}</dd> <dt>Password</dt> <dd>{{ input_field('password', type='password') }}</dd></dl><p>{{ textarea('comment') }}</p>

Macros and variables starting with one or more underscores are private andcannot be imported.

Changelog

Changed in version 2.4: If a template object was passed to the template context, you canimport from that object.

Import Context Behavior¶

By default, included templates are passed the current context and importedtemplates are not. The reason for this is that imports, unlike includes,are cached; as imports are often used just as a module that holds macros.

This behavior can be changed explicitly: by adding with contextor without context to the import/include directive, the current contextcan be passed to the template and caching is disabled automatically.

Here are two examples:

{% from 'forms.html' import input with context %}{% include 'header.html' without context %}

Note

In Jinja 2.0, the context that was passed to the included templatedid not include variables defined in the template. As a matter offact, this did not work:

{% for box in boxes %} {% include "render_box.html" %}{% endfor %}

The included template render_box.html is not able to accessbox in Jinja 2.0. As of Jinja 2.1, render_box.html is ableto do so.

Expressions¶

Jinja allows basic expressions everywhere. These work very similarly toregular Python; even if you’re not working with Pythonyou should feel comfortable with it.

Literals¶

The simplest form of expressions are literals. Literals are representationsfor Python objects such as strings and numbers. The following literals exist:

"Hello World"

Everything between two double or single quotes is a string. They areuseful whenever you need a string in the template (e.g. asarguments to function calls and filters, or just to extend or include atemplate).

42 / 123_456

Integers are whole numbers without a decimal part. The ‘_’ charactercan be used to separate groups for legibility.

42.23 / 42.1e2 / 123_456.789

Floating point numbers can be written using a ‘.’ as a decimal mark.They can also be written in scientific notation with an upper orlower case ‘e’ to indicate the exponent part. The ‘_’ character canbe used to separate groups for legibility, but cannot be used in theexponent part.

['list', 'of', 'objects']

Everything between two brackets is a list. Lists are useful for storingsequential data to be iterated over. For example, you can easilycreate a list of links using lists and tuples for (and with) a for loop:

<ul>{% for href, caption in [('index.html', 'Index'), ('about.html', 'About'), ('downloads.html', 'Downloads')] %} <li><a href="{{ href }}">{{ caption }}</a></li>{% endfor %}</ul>

('tuple', 'of', 'values')

Tuples are like lists that cannot be modified (“immutable”). If a tupleonly has one item, it must be followed by a comma (('1-tuple',)).Tuples are usually used to represent items of two or more elements.See the list example above for more details.

{'dict': 'of', 'key': 'and', 'value': 'pairs'}

A dict in Python is a structure that combines keys and values. Keys mustbe unique and always have exactly one value. Dicts are rarely used intemplates; they are useful in some rare cases such as the xmlattr()filter.

true / false

true is always true and false is always false.

Note

The special constants true, false, and none are indeed lowercase.Because that caused confusion in the past, (True used to expandto an undefined variable that was considered false),all three can now also be written in title case(True, False, and None).However, for consistency, (all Jinja identifiers are lowercase)you should use the lowercase versions.

Math¶

Jinja allows you to calculate with values. This is rarely useful in templatesbut exists for completeness’ sake. The following operators are supported:

+

Adds two objects together. Usually the objects are numbers, but if both arestrings or lists, you can concatenate them this way. This, however, is notthe preferred way to concatenate strings! For string concatenation, havea look-see at the ~ operator. {{ 1 + 1 }} is 2.

-

Subtract the second number from the first one. {{ 3 - 2 }} is 1.

/

Divide two numbers. The return value will be a floating point number.{{ 1 / 2 }} is {{ 0.5 }}.

//

Divide two numbers and return the truncated integer result.{{ 20 // 7 }} is 2.

%

Calculate the remainder of an integer division. {{ 11 % 7 }} is 4.

*

Multiply the left operand with the right one. {{ 2 * 2 }} wouldreturn 4. This can also be used to repeat a string multiple times.{{ '=' * 80 }} would print a bar of 80 equal signs.

**

Raise the left operand to the power of the right operand.{{ 2**3 }} would return 8.

Unlike Python, chained pow is evaluated left to right.{{ 3**3**3 }} is evaluated as (3**3)**3 in Jinja, but wouldbe evaluated as 3**(3**3) in Python. Use parentheses in Jinjato be explicit about what order you want. It is usually preferableto do extended math in Python and pass the results to renderrather than doing it in the template.

This behavior may be changed in the future to match Python, if it’spossible to introduce an upgrade path.

Comparisons¶

==: Compares two objects for equality.
!=: Compares two objects for inequality.
>: true if the left hand side is greater than the right hand side.
>=: true if the left hand side is greater or equal to the right hand side.
<: true if the left hand side is lower than the right hand side.
<=: true if the left hand side is lower or equal to the right hand side.

Logic¶

For if statements, for filtering, and if expressions, it can be useful tocombine multiple expressions:

and: Return true if the left and the right operand are true.
or: Return true if the left or the right operand are true.
not: negate a statement (see below).
(expr): Parentheses group an expression.

Note

The is and in operators support negation using an infix notation,too: foo is not bar and foo not in bar instead of not foo is barand not foo in bar. All other expressions require a prefix notation:not (foo and bar).

Other Operators¶

The following operators are very useful but don’t fit into any of the othertwo categories:

in

Perform a sequence / mapping containment test. Returns true if the leftoperand is contained in the right. {{ 1 in [1, 2, 3] }} would, forexample, return true.

is

Performs a test.

| (pipe, vertical bar)

Applies a filter.

~ (tilde)

Converts all operands into strings and concatenates them.

{{ "Hello " ~ name ~ "!" }} would return (assuming name is setto 'John') Hello John!.

()

Call a callable: {{ post.render() }}. Inside of the parentheses youcan use positional arguments and keyword arguments like in Python:

{{ post.render(user, full=true) }}.

. / []

Get an attribute of an object. (See Variables)

If Expression¶

It is also possible to use inline if expressions. These are useful in somesituations. For example, you can use this to extend from one template if avariable is defined, otherwise from the default layout template:

{% extends layout_template if layout_template is defined else 'default.html' %}

The general syntax is <do something> if <something is true> else <dosomething else>.

The else part is optional. If not provided, the else block implicitlyevaluates into an Undefined object (regardless of what undefinedin the environment is set to):

{{ "[{}]".format(page.title) if page.title }}

Python Methods¶

You can also use any of the methods defined on a variable’s type.The value returned from the method invocation is used as the value of the expression.Here is an example that uses methods defined on strings (where page.title is a string):

{{ page.title.capitalize() }}

This works for methods on user-defined types. For example, if variablef of type Foo has a method bar defined on it, you can do thefollowing:

{{ f.bar(value) }}

Operator methods also work as expected. For example, % implementsprintf-style for strings:

{{ "Hello, %s!" % name }}

Although you should prefer the .format method for that case (whichis a bit contrived in the context of rendering a template):

{{ "Hello, {}!".format(name) }}

List of Builtin Filters¶

abs()	float()	lower()	round()	tojson()
attr()	forceescape()	map()	safe()	trim()
batch()	format()	max()	select()	truncate()
capitalize()	groupby()	min()	selectattr()	unique()
center()	indent()	pprint()	slice()	upper()
default()	int()	random()	sort()	urlencode()
dictsort()	join()	reject()	string()	urlize()
escape()	last()	rejectattr()	striptags()	wordcount()
filesizeformat()	length()	replace()	sum()	wordwrap()
first()	list()	reverse()	title()	xmlattr()

jinja-filters.abs(x, /)¶: Return the absolute value of the argument.

jinja-filters.attr(obj: Any, name: str) → Union[jinja2.runtime.Undefined, Any]¶

Get an attribute of an object. foo|attr("bar") works likefoo.bar just that always an attribute is returned and items are notlooked up.

See Notes on subscriptions for more details.

jinja-filters.batch(value: 't.Iterable[V]', linecount: int, fill_with: 't.Optional[V]' = None) → 't.Iterator[t.List[V]]'¶

A filter that batches items. It works pretty much like slicejust the other way round. It returns a list of lists with thegiven number of items. If you provide a second parameter thisis used to fill up missing items. See this example:

<table>{%- for row in items|batch(3, '&nbsp;') %} <tr> {%- for column in row %} <td>{{ column }}</td> {%- endfor %} </tr>{%- endfor %}</table>

jinja-filters.capitalize(s: str) → str¶: Capitalize a value. The first character will be uppercase, all otherslowercase.

jinja-filters.center(value: str, width: int = 80) → str¶: Centers the value in a field of a given width.

jinja-filters.default(value: V, default_value: V = '', boolean: bool = False) → V¶

If the value is undefined it will return the passed default value,otherwise the value of the variable:

{{ my_variable|default('my_variable is not defined') }}

This will output the value of my_variable if the variable wasdefined, otherwise 'my_variable is not defined'. If you wantto use default with variables that evaluate to false you have toset the second parameter to true:

{{ ''|default('the string was empty', true) }}

Changelog

Changed in version 2.11: It’s now possible to configure the Environment withChainableUndefined to make the default filter workon nested elements and attributes that may contain undefined valuesin the chain without getting an UndefinedError.

Aliases: d

jinja-filters.dictsort(value: Mapping[K, V], case_sensitive: bool = False, by: 'te.Literal["key", "value"]' = 'key', reverse: bool = False) → List[Tuple[K, V]]¶

Sort a dict and yield (key, value) pairs. Python dicts may notbe in the order you want to display them in, so sort them first.

{% for key, value in mydict|dictsort %} sort the dict by key, case insensitive{% for key, value in mydict|dictsort(reverse=true) %} sort the dict by key, case insensitive, reverse order{% for key, value in mydict|dictsort(true) %} sort the dict by key, case sensitive{% for key, value in mydict|dictsort(false, 'value') %} sort the dict by value, case insensitive

jinja-filters.escape(value)¶

Replace the characters &, <, >, ', and " in the string with HTML-safe sequences. Use this if you need to display text that might contain such characters in HTML.

If the object has an __html__ method, it is called and the return value is assumed to already be safe for HTML.

Parameters: s – An object to be converted to a string and escaped.
Returns: A Markup string with the escaped text.
Aliases: e

jinja-filters.filesizeformat(value: Union[str, float, int], binary: bool = False) → str¶: Format the value like a ‘human-readable’ file size (i.e. 13 kB,4.1 MB, 102 Bytes, etc). Per default decimal prefixes are used (Mega,Giga, etc.), if the second parameter is set to True the binaryprefixes are used (Mebi, Gibi).

jinja-filters.first(seq: 't.Iterable[V]') → 't.Union[V, Undefined]'¶: Return the first item of a sequence.

jinja-filters.float(value: Any, default: float = 0.0) → float¶: Convert the value into a floating point number. If theconversion doesn’t work it will return 0.0. You canoverride this default using the first parameter.

jinja-filters.forceescape(value: 't.Union[str, HasHTML]') → markupsafe.Markup¶: Enforce HTML escaping. This will probably double escape variables.

jinja-filters.format(value: str, *args: Any, **kwargs: Any) → str¶

Apply the given values to a printf-style format string, likestring % values.

{{ "%s, %s!"|format(greeting, name) }}Hello, World!

In most cases it should be more convenient and efficient to use the% operator or str.format().

{{ "%s, %s!" % (greeting, name) }}{{ "{}, {}!".format(greeting, name) }}

jinja-filters.groupby(value: 't.Iterable[V]', attribute: Union[str, int], default: Optional[Any] = None) → 't.List[t.Tuple[t.Any, t.List[V]]]'¶

Group a sequence of objects by an attribute using Python’sitertools.groupby(). The attribute can use dot notation fornested access, like "address.city". Unlike Python’s groupby,the values are sorted first so only one group is returned for eachunique value.

For example, a list of User objects with a city attributecan be rendered in groups. In this example, grouper refers tothe city value of the group.

<ul>{% for city, items in users|groupby("city") %} <li>{{ city }} <ul>{% for user in items %} <li>{{ user.name }} {% endfor %}</ul> </li>{% endfor %}</ul>

groupby yields namedtuples of (grouper, list), whichcan be used instead of the tuple unpacking above. grouper is thevalue of the attribute, and list is the items with that value.

<ul>{% for group in users|groupby("city") %} <li>{{ group.grouper }}: {{ group.list|join(", ") }}{% endfor %}</ul>

You can specify a default value to use if an object in the listdoes not have the given attribute.

<ul>{% for city, items in users|groupby("city", default="NY") %} <li>{{ city }}: {{ items|map(attribute="name")|join(", ") }}</li>{% endfor %}</ul>

Changed in version 3.0: Added the default parameter.

Changelog

Changed in version 2.6: The attribute supports dot notation for nested access.

jinja-filters.indent(s: str, width: Union[int, str] = 4, first: bool = False, blank: bool = False) → str¶

Return a copy of the string with each line indented by 4 spaces. Thefirst line and blank lines are not indented by default.

Parameters

width – Number of spaces, or a string, to indent by.
first – Don’t skip indenting the first line.
blank – Don’t skip indenting empty lines.

Changed in version 3.0: width can be a string.

Changelog

Changed in version 2.10: Blank lines are not indented by default.

Rename the indentfirst argument to first.

jinja-filters.int(value: Any, default: int = 0, base: int = 10) → int¶: Convert the value into an integer. If theconversion doesn’t work it will return 0. You canoverride this default using the first parameter. Youcan also override the default base (10) in the secondparameter, which handles input with prefixes such as0b, 0o and 0x for bases 2, 8 and 16 respectively.The base is ignored for decimal numbers and non-string values.

jinja-filters.join(value: Iterable, d: str = '', attribute: Union[str, int, NoneType] = None) → str¶

Return a string which is the concatenation of the strings in thesequence. The separator between elements is an empty string perdefault, you can define it with the optional parameter:

{{ [1, 2, 3]|join('|') }} -> 1|2|3{{ [1, 2, 3]|join }} -> 123

It is also possible to join certain attributes of an object:

{{ users|join(', ', attribute='username') }}

Changelog

New in version 2.6: The attribute parameter was added.

jinja-filters.last(seq: 't.Reversible[V]') → 't.Union[V, Undefined]'¶

Return the last item of a sequence.

Note: Does not work with generators. You may want to explicitlyconvert it to a list:

{{ data | selectattr('name', '==', 'Jinja') | list | last }}

jinja-filters.length(obj, /)¶

Return the number of items in a container.

Aliases: count

jinja-filters.list(value: 't.Iterable[V]') → 't.List[V]'¶: Convert the value into a list. If it was a string the returned listwill be a list of characters.

jinja-filters.lower(s: str) → str¶: Convert a value to lowercase.

jinja-filters.map(value: Iterable, *args: Any, **kwargs: Any) → Iterable¶

Applies a filter on a sequence of objects or looks up an attribute.This is useful when dealing with lists of objects but you are reallyonly interested in a certain value of it.

The basic usage is mapping on an attribute. Imagine you have a listof users but you are only interested in a list of usernames:

Users on this page: {{ users|map(attribute='username')|join(', ') }}

You can specify a default value to use if an object in the listdoes not have the given attribute.

{{ users|map(attribute="username", default="Anonymous")|join(", ") }}

Alternatively you can let it invoke a filter by passing the name of thefilter and the arguments afterwards. A good example would be applying atext conversion filter on a sequence:

Users on this page: {{ titles|map('lower')|join(', ') }}

Similar to a generator comprehension such as:

(u.username for u in users)(getattr(u, "username", "Anonymous") for u in users)(do_lower(x) for x in titles)

Changelog

Changed in version 2.11.0: Added the default parameter.

New in version 2.7.

jinja-filters.max(value: 't.Iterable[V]', case_sensitive: bool = False, attribute: Union[str, int, NoneType] = None) → 't.Union[V, Undefined]'¶

Return the largest item from the sequence.

{{ [1, 2, 3]|max }} -> 3

Parameters

case_sensitive – Treat upper and lower case strings as distinct.
attribute – Get the object with the max value of this attribute.

jinja-filters.min(value: 't.Iterable[V]', case_sensitive: bool = False, attribute: Union[str, int, NoneType] = None) → 't.Union[V, Undefined]'¶

Return the smallest item from the sequence.

{{ [1, 2, 3]|min }} -> 1

Parameters

case_sensitive – Treat upper and lower case strings as distinct.
attribute – Get the object with the min value of this attribute.

jinja-filters.pprint(value: Any) → str¶: Pretty print a variable. Useful for debugging.

jinja-filters.random(seq: 't.Sequence[V]') → 't.Union[V, Undefined]'¶: Return a random item from the sequence.

jinja-filters.reject(value: 't.Iterable[V]', *args: Any, **kwargs: Any) → 't.Iterator[V]'¶

Filters a sequence of objects by applying a test to each object,and rejecting the objects with the test succeeding.

If no test is specified, each object will be evaluated as a boolean.

Example usage:

{{ numbers|reject("odd") }}

Similar to a generator comprehension such as:

(n for n in numbers if not test_odd(n))

Changelog

New in version 2.7.

jinja-filters.rejectattr(value: 't.Iterable[V]', *args: Any, **kwargs: Any) → 't.Iterator[V]'¶

Filters a sequence of objects by applying a test to the specifiedattribute of each object, and rejecting the objects with the testsucceeding.

If no test is specified, the attribute’s value will be evaluated asa boolean.

{{ users|rejectattr("is_active") }}{{ users|rejectattr("email", "none") }}

Similar to a generator comprehension such as:

(u for user in users if not user.is_active)(u for user in users if not test_none(user.email))

Changelog

New in version 2.7.

jinja-filters.replace(s: str, old: str, new: str, count: Optional[int] = None) → str¶

Return a copy of the value with all occurrences of a substringreplaced with a new one. The first argument is the substringthat should be replaced, the second is the replacement string.If the optional third argument count is given, only the firstcount occurrences are replaced:

{{ "Hello World"|replace("Hello", "Goodbye") }} -> Goodbye World{{ "aaaaargh"|replace("a", "d'oh, ", 2) }} -> d'oh, d'oh, aaargh

jinja-filters.reverse(value: Union[str, Iterable[V]]) → Union[str, Iterable[V]]¶: Reverse the object or return an iterator that iterates over it the otherway round.

jinja-filters.round(value: float, precision: int = 0, method: 'te.Literal["common", "ceil", "floor"]' = 'common') → float¶

Round the number to a given precision. The firstparameter specifies the precision (default is 0), thesecond the rounding method:

'common' rounds either up or down
'ceil' always rounds up
'floor' always rounds down

If you don’t specify a method 'common' is used.

{{ 42.55|round }} -> 43.0{{ 42.55|round(1, 'floor') }} -> 42.5

Note that even if rounded to 0 precision, a float is returned. Ifyou need a real integer, pipe it through int:

{{ 42.55|round|int }} -> 43

jinja-filters.safe(value: str) → markupsafe.Markup¶: Mark the value as safe which means that in an environment with automaticescaping enabled this variable will not be escaped.

jinja-filters.select(value: 't.Iterable[V]', *args: Any, **kwargs: Any) → 't.Iterator[V]'¶

Filters a sequence of objects by applying a test to each object,and only selecting the objects with the test succeeding.

If no test is specified, each object will be evaluated as a boolean.

Example usage:

{{ numbers|select("odd") }}{{ numbers|select("odd") }}{{ numbers|select("divisibleby", 3) }}{{ numbers|select("lessthan", 42) }}{{ strings|select("equalto", "mystring") }}

Similar to a generator comprehension such as:

(n for n in numbers if test_odd(n))(n for n in numbers if test_divisibleby(n, 3))

Changelog

New in version 2.7.

jinja-filters.selectattr(value: 't.Iterable[V]', *args: Any, **kwargs: Any) → 't.Iterator[V]'¶

Filters a sequence of objects by applying a test to the specifiedattribute of each object, and only selecting the objects with thetest succeeding.

If no test is specified, the attribute’s value will be evaluated asa boolean.

Example usage:

{{ users|selectattr("is_active") }}{{ users|selectattr("email", "none") }}

Similar to a generator comprehension such as:

(u for user in users if user.is_active)(u for user in users if test_none(user.email))

Changelog

New in version 2.7.

jinja-filters.slice(value: 't.Collection[V]', slices: int, fill_with: 't.Optional[V]' = None) → 't.Iterator[t.List[V]]'¶

Slice an iterator and return a list of lists containingthose items. Useful if you want to create a div containingthree ul tags that represent columns:

<div class="columnwrapper"> {%- for column in items|slice(3) %} <ul class="column-{{ loop.index }}"> {%- for item in column %} <li>{{ item }}</li> {%- endfor %} </ul> {%- endfor %}</div>

If you pass it a second argument it’s used to fill missingvalues on the last iteration.

jinja-filters.sort(value: 't.Iterable[V]', reverse: bool = False, case_sensitive: bool = False, attribute: Union[str, int, NoneType] = None) → 't.List[V]'¶

Sort an iterable using Python’s sorted().

{% for city in cities|sort %} ...{% endfor %}

Parameters

reverse – Sort descending instead of ascending.
case_sensitive – When sorting strings, sort upper and lowercase separately.
attribute – When sorting objects or dicts, an attribute orkey to sort by. Can use dot notation like "address.city".Can be a list of attributes like "age,name".

The sort is stable, it does not change the relative order ofelements that compare equal. This makes it is possible to chainsorts on different attributes and ordering.

{% for user in users|sort(attribute="name") |sort(reverse=true, attribute="age") %} ...{% endfor %}

As a shortcut to chaining when the direction is the same for allattributes, pass a comma separate list of attributes.

{% for user in users|sort(attribute="age,name") %} ...{% endfor %}

Changelog

Changed in version 2.11.0: The attribute parameter can be a comma separated list ofattributes, e.g. "age,name".

Changed in version 2.6: The attribute parameter was added.

jinja-filters.string(value)¶

Convert an object to a string if it isn’t already. This preserves a Markup string rather than converting it back to a basic string, so it will still be marked as safe and won’t be escaped again.

>>> value = escape("<User 1>")>>> valueMarkup('&lt;User 1&gt;')>>> escape(str(value))Markup('&amp;lt;User 1&amp;gt;')>>> escape(soft_str(value))Markup('&lt;User 1&gt;')

jinja-filters.striptags(value: 't.Union[str, HasHTML]') → str¶: Strip SGML/XML tags and replace adjacent whitespace by one space.

jinja-filters.sum(iterable: 't.Iterable[V]', attribute: Union[str, int, NoneType] = None, start: V = 0) → V¶

Returns the sum of a sequence of numbers plus the value of parameter‘start’ (which defaults to 0). When the sequence is empty it returnsstart.

It is also possible to sum up only certain attributes:

Total: {{ items|sum(attribute='price') }}

Changelog

Changed in version 2.6: The attribute parameter was added to allow suming up overattributes. Also the start parameter was moved on to the right.

jinja-filters.title(s: str) → str¶: Return a titlecased version of the value. I.e. words will start withuppercase letters, all remaining characters are lowercase.

jinja-filters.tojson(value: Any, indent: Optional[int] = None) → markupsafe.Markup¶

Serialize an object to a string of JSON, and mark it safe torender in HTML. This filter is only for use in HTML documents.

The returned string is safe to render in HTML documents and<script> tags. The exception is in HTML attributes that aredouble quoted; either use single quotes or the |forceescapefilter.

Parameters

value – The object to serialize to JSON.
indent – The indent parameter passed to dumps, forpretty-printing the value.

Changelog

New in version 2.9.

jinja-filters.trim(value: str, chars: Optional[str] = None) → str¶: Strip leading and trailing characters, by default whitespace.

jinja-filters.truncate(s: str, length: int = 255, killwords: bool = False, end: str = '...', leeway: Optional[int] = None) → str¶

Return a truncated copy of the string. The length is specifiedwith the first parameter which defaults to 255. If the secondparameter is true the filter will cut the text at length. Otherwiseit will discard the last word. If the text was in facttruncated it will append an ellipsis sign ("..."). If you want adifferent ellipsis sign than "..." you can specify it using thethird parameter. Strings that only exceed the length by the tolerancemargin given in the fourth parameter will not be truncated.

{{ "foo bar baz qux"|truncate(9) }} -> "foo..."{{ "foo bar baz qux"|truncate(9, True) }} -> "foo ba..."{{ "foo bar baz qux"|truncate(11) }} -> "foo bar baz qux"{{ "foo bar baz qux"|truncate(11, False, '...', 0) }} -> "foo bar..."

The default leeway on newer Jinja versions is 5 and was 0 before butcan be reconfigured globally.

jinja-filters.unique(value: 't.Iterable[V]', case_sensitive: bool = False, attribute: Union[str, int, NoneType] = None) → 't.Iterator[V]'¶

Returns a list of unique items from the given iterable.

{{ ['foo', 'bar', 'foobar', 'FooBar']|unique|list }} -> ['foo', 'bar', 'foobar']

The unique items are yielded in the same order as their first occurrence inthe iterable passed to the filter.

Parameters

case_sensitive – Treat upper and lower case strings as distinct.
attribute – Filter objects with unique values for this attribute.

jinja-filters.upper(s: str) → str¶: Convert a value to uppercase.

jinja-filters.urlencode(value: Union[str, Mapping[str, Any], Iterable[Tuple[str, Any]]]) → str¶

Quote data for use in a URL path or query using UTF-8.

Basic wrapper around urllib.parse.quote() when given astring, or urllib.parse.urlencode() for a dict or iterable.

Parameters: value – Data to quote. A string will be quoted directly. Adict or iterable of (key, value) pairs will be joined as aquery string.

When given a string, “/” is not quoted. HTTP servers treat “/” and“%2F” equivalently in paths. If you need quoted slashes, use the|replace("/", "%2F") filter.

Changelog

New in version 2.7.

jinja-filters.urlize(value: str, trim_url_limit: Optional[int] = None, nofollow: bool = False, target: Optional[str] = None, rel: Optional[str] = None, extra_schemes: Optional[Iterable[str]] = None) → str¶

Convert URLs in text into clickable links.

This may not recognize links in some situations. Usually, a morecomprehensive formatter, such as a Markdown library, is a betterchoice.

Works on http://, https://, www., mailto:, and emailaddresses. Links with trailing punctuation (periods, commas, closingparentheses) and leading punctuation (opening parentheses) arerecognized excluding the punctuation. Email addresses that includeheader fields are not recognized (for example,mailto:address@example.com?cc=copy@example.com).

Parameters

value – Original text containing URLs to link.
trim_url_limit – Shorten displayed URL values to this length.
nofollow – Add the rel=nofollow attribute to links.
target – Add the target attribute to links.
rel – Add the rel attribute to links.
extra_schemes – Recognize URLs that start with these schemesin addition to the default behavior. Defaults toenv.policies["urlize.extra_schemes"], which defaults to noextra schemes.

Changed in version 3.0: The extra_schemes parameter was added.

Changed in version 3.0: Generate https:// links for URLs without a scheme.

Changed in version 3.0: The parsing rules were updated. Recognize email addresses withor without the mailto: scheme. Validate IP addresses. Ignoreparentheses and brackets in more cases.

Changelog

Changed in version 2.8: The target parameter was added.

jinja-filters.wordcount(s: str) → int¶: Count the words in that string.

jinja-filters.wordwrap(s: str, width: int = 79, break_long_words: bool = True, wrapstring: Optional[str] = None, break_on_hyphens: bool = True) → str¶

Wrap a string to the given width. Existing newlines are treatedas paragraphs to be wrapped separately.

Parameters

s – Original text to wrap.
width – Maximum length of wrapped lines.
break_long_words – If a word is longer than width, breakit across lines.
break_on_hyphens – If a word contains hyphens, it may be splitacross lines.
wrapstring – String to join each wrapped line. Defaults toEnvironment.newline_sequence.

Changelog

Changed in version 2.11: Existing newlines are treated as paragraphs wrapped separately.

Changed in version 2.11: Added the break_on_hyphens parameter.

Changed in version 2.7: Added the wrapstring parameter.

jinja-filters.xmlattr(d: Mapping[str, Any], autospace: bool = True) → str¶

Create an SGML/XML attribute string based on the items in a dict.All values that are neither none nor undefined are automaticallyescaped:

<ul{{ {'class': 'my_list', 'missing': none, 'id': 'list-%d'|format(variable)}|xmlattr }}>...</ul>

Results in something like this:

<ul class="my_list" id="list-42">...</ul>

As you can see it automatically prepends a space in front of the itemif the filter returned something unless the second parameter is false.

List of Builtin Tests¶

boolean()	even()	in()	mapping()	sequence()
callable()	false()	integer()	ne()	string()
defined()	filter()	iterable()	none()	test()
divisibleby()	float()	le()	number()	true()
eq()	ge()	lower()	odd()	undefined()
escaped()	gt()	lt()	sameas()	upper()

jinja-tests.boolean(value: Any) → bool¶: Return true if the object is a boolean value.
Changelog
New in version 2.11.

jinja-tests.callable(obj, /)¶

Return whether the object is callable (i.e., some kind of function).

Note that classes are callable, as are instances of classes with a__call__() method.

jinja-tests.defined(value: Any) → bool¶

Return true if the variable is defined:

{% if variable is defined %} value of variable: {{ variable }}{% else %} variable is not defined{% endif %}

See the default() filter for a simple way to set undefinedvariables.

jinja-tests.divisibleby(value: int, num: int) → bool¶: Check if a variable is divisible by a number.

jinja-tests.eq(a, b, /)¶

Same as a == b.

Aliases: ==, equalto

jinja-tests.escaped(value: Any) → bool¶: Check if the value is escaped.

jinja-tests.even(value: int) → bool¶: Return true if the variable is even.

jinja-tests.false(value: Any) → bool¶: Return true if the object is False.
Changelog
New in version 2.11.

jinja-tests.filter(value: str) → bool¶

Check if a filter exists by name. Useful if a filter may beoptionally available.

{% if 'markdown' is filter %} {{ value | markdown }}{% else %} {{ value }}{% endif %}

New in version 3.0.

jinja-tests.float(value: Any) → bool¶: Return true if the object is a float.
Changelog
New in version 2.11.

jinja-tests.ge(a, b, /)¶

Same as a >= b.

Aliases: >=

jinja-tests.gt(a, b, /)¶

Same as a > b.

Aliases: >, greaterthan

jinja-tests.in(value: Any, seq: Container) → bool¶: Check if value is in seq.
Changelog
New in version 2.10.

jinja-tests.integer(value: Any) → bool¶: Return true if the object is an integer.
Changelog
New in version 2.11.

jinja-tests.iterable(value: Any) → bool¶: Check if it’s possible to iterate over an object.

jinja-tests.le(a, b, /)¶

Same as a <= b.

Aliases: <=

jinja-tests.lower(value: str) → bool¶: Return true if the variable is lowercased.

jinja-tests.lt(a, b, /)¶

Same as a < b.

Aliases: <, lessthan

jinja-tests.mapping(value: Any) → bool¶: Return true if the object is a mapping (dict etc.).
Changelog
New in version 2.6.

jinja-tests.ne(a, b, /)¶

Same as a != b.

Aliases: !=

jinja-tests.none(value: Any) → bool¶: Return true if the variable is none.

jinja-tests.number(value: Any) → bool¶: Return true if the variable is a number.

jinja-tests.odd(value: int) → bool¶: Return true if the variable is odd.

jinja-tests.sameas(value: Any, other: Any) → bool¶

Check if an object points to the same memory address than anotherobject:

{% if foo.attribute is sameas false %} the foo attribute really is the `False` singleton{% endif %}

jinja-tests.sequence(value: Any) → bool¶: Return true if the variable is a sequence. Sequences are variablesthat are iterable.

jinja-tests.string(value: Any) → bool¶: Return true if the object is a string.

jinja-tests.test(value: str) → bool¶

Check if a test exists by name. Useful if a test may beoptionally available.

{% if 'loud' is test %} {% if value is loud %} {{ value|upper }} {% else %} {{ value|lower }} {% endif %}{% else %} {{ value }}{% endif %}

New in version 3.0.

jinja-tests.true(value: Any) → bool¶: Return true if the object is True.
Changelog
New in version 2.11.

jinja-tests.undefined(value: Any) → bool¶: Like defined() but the other way round.

jinja-tests.upper(value: str) → bool¶: Return true if the variable is uppercased.

List of Global Functions¶

The following functions are available in the global scope by default:

jinja-globals.range([start, ]stop[, step])¶

Return a list containing an arithmetic progression of integers.range(i, j) returns [i, i+1, i+2, ..., j-1];start (!) defaults to 0.When step is given, it specifies the increment (or decrement).For example, range(4) and range(0, 4, 1) return [0, 1, 2, 3].The end point is omitted!These are exactly the valid indices for a list of 4 elements.

This is useful to repeat a template block multiple times, e.g.to fill a list. Imagine you have 7 users in the list but you want torender three empty items to enforce a height with CSS:

<ul>{% for user in users %} <li>{{ user.username }}</li>{% endfor %}{% for number in range(10 - users|count) %} <li class="empty"><span>...</span></li>{% endfor %}</ul>

jinja-globals.lipsum(n=5, html=True, min=20, max=100)¶: Generates some lorem ipsum for the template. By default, five paragraphsof HTML are generated with each paragraph between 20 and 100 words.If html is False, regular text is returned. This is useful to generate simplecontents for layout testing.

jinja-globals.dict(\**items)¶: A convenient alternative to dict literals. {'foo': 'bar'} is the sameas dict(foo='bar').

class jinja-globals.cycler(\*items)¶

Cycle through values by yielding them one at a time, then restartingonce the end is reached.

Similar to loop.cycle, but can be used outside loops or acrossmultiple loops. For example, render a list of folders and files in alist, alternating giving them “odd” and “even” classes.

{% set row_class = cycler("odd", "even") %}<ul class="browser">{% for folder in folders %} <li class="folder {{ row_class.next() }}">{{ folder }}{% endfor %}{% for file in files %} <li class="file {{ row_class.next() }}">{{ file }}{% endfor %}</ul>

Parameters: items – Each positional argument will be yielded in the ordergiven for each cycle.

Changelog

New in version 2.1.

property current¶: Return the current item. Equivalent to the item that will bereturned next time next() is called.

next()¶: Return the current item, then advance current to thenext item.

reset()¶: Resets the current item to the first item.

class jinja-globals.joiner(sep=', ')¶

A tiny helper that can be used to “join” multiple sections. A joiner ispassed a string and will return that string every time it’s called, exceptthe first time (in which case it returns an empty string). You canuse this to join things:

{% set pipe = joiner("|") %}{% if categories %} {{ pipe() }} Categories: {{ categories|join(", ") }}{% endif %}{% if author %} {{ pipe() }} Author: {{ author() }}{% endif %}{% if can_edit %} {{ pipe() }} <a href="?action=edit">Edit</a>{% endif %}

Changelog

New in version 2.1.

class jinja-globals.namespace(...)¶

Creates a new container that allows attribute assignment using the{% set %} tag:

{% set ns = namespace() %}{% set ns.foo = 'bar' %}

The main purpose of this is to allow carrying a value from within a loopbody to an outer scope. Initial values can be provided as a dict, askeyword arguments, or both (same behavior as Python’s dict constructor):

{% set ns = namespace(found=false) %}{% for item in items %} {% if item.check_something() %} {% set ns.found = true %} {% endif %} * {{ item.title }}{% endfor %}Found item having something: {{ ns.found }}

Changelog

New in version 2.10.

Extensions¶

The following sections cover the built-in Jinja extensions that may beenabled by an application. An application could also provide furtherextensions not covered by this documentation; in which case there shouldbe a separate document explaining said extensions.

i18n¶

If the i18n Extension is enabled, it’s possible to mark text inthe template as translatable. To mark a section as translatable, use atrans block:

{% trans %}Hello, {{ user }}!{% endtrans %}

Inside the block, no statements are allowed, only text and simplevariable tags.

Variable tags can only be a name, not attribute access, filters, orother expressions. To use an expression, bind it to a name in thetrans tag for use in the block.

{% trans user=user.username %}Hello, {{ user }}!{% endtrans %}

To bind more than one expression, separate each with a comma (,).

{% trans book_title=book.title, author=author.name %}This is {{ book_title }} by {{ author }}{% endtrans %}

To pluralize, specify both the singular and plural forms separated bythe pluralize tag.

{% trans count=list|length %}There is {{ count }} {{ name }} object.{% pluralize %}There are {{ count }} {{ name }} objects.{% endtrans %}

By default, the first variable in a block is used to determine whetherto use singular or plural form. If that isn’t correct, specify thevariable used for pluralizing as a parameter to pluralize.

{% trans ..., user_count=users|length %}...{% pluralize user_count %}...{% endtrans %}

When translating blocks of text, whitespace and linebreaks result inhard to read and error-prone translation strings. To avoid this, a transblock can be marked as trimmed, which will replace all linebreaks andthe whitespace surrounding them with a single space and remove leadingand trailing whitespace.

{% trans trimmed book_title=book.title %} This is {{ book_title }}. You should read it!{% endtrans %}

This results in This is %(book_title)s. You should read it! in thetranslation file.

If trimming is enabled globally, the notrimmed modifier can be usedto disable it for a block.

Changelog

New in version 2.10: The trimmed and notrimmed modifiers have been added.

It’s possible to translate strings in expressions with these functions:

gettext: translate a single string
ngettext: translate a pluralizable string
_: alias for gettext

You can print a translated string like this:

{{ _("Hello, World!") }}

To use placeholders, use the format filter.

{{ _("Hello, %(user)s!")|format(user=user.username) }}

Always use keyword arguments to format, as other languages may notuse the words in the same order.

If New Style Gettext calls are activated, using placeholders iseasier. Formatting is part of the gettext call instead of using theformat filter.

{{ gettext('Hello World!') }}{{ gettext('Hello %(name)s!', name='World') }}{{ ngettext('%(num)d apple', '%(num)d apples', apples|count) }}

The ngettext function’s format string automatically receives thecount as a num parameter in addition to the given parameters.

Expression Statement¶

If the expression-statement extension is loaded, a tag called do is availablethat works exactly like the regular variable expression ({{ ... }}); exceptit doesn’t print anything. This can be used to modify lists:

{% do navigation.append('a string') %}

Loop Controls¶

If the application enables the Loop Controls, it’s possible touse break and continue in loops. When break is reached, the loop isterminated; if continue is reached, the processing is stopped and continueswith the next iteration.

Here’s a loop that skips every second item:

{% for user in users %} {%- if loop.index is even %}{% continue %}{% endif %} ...{% endfor %}

Likewise, a loop that stops processing after the 10th iteration:

{% for user in users %} {%- if loop.index >= 10 %}{% break %}{% endif %}{%- endfor %}

Note that loop.index starts with 1, and loop.index0 starts with 0(See: For).

Debug Statement¶

If the Debug Extension is enabled, a {% debug %} tag will beavailable to dump the current context as well as the available filtersand tests. This is useful to see what’s available to use in the templatewithout setting up a debugger.

<pre>{% debug %}</pre>

{'context': {'cycler': <class 'jinja2.utils.Cycler'>, ..., 'namespace': <class 'jinja2.utils.Namespace'>}, 'filters': ['abs', 'attr', 'batch', 'capitalize', 'center', 'count', 'd', ..., 'urlencode', 'urlize', 'wordcount', 'wordwrap', 'xmlattr'], 'tests': ['!=', '<', '<=', '==', '>', '>=', 'callable', 'defined', ..., 'odd', 'sameas', 'sequence', 'string', 'undefined', 'upper']}

With Statement¶

Changelog

New in version 2.3.

The with statement makes it possible to create a new inner scope.Variables set within this scope are not visible outside of the scope.

With in a nutshell:

{% with %} {% set foo = 42 %} {{ foo }} foo is 42 here{% endwith %}foo is not visible here any longer

Because it is common to set variables at the beginning of the scope,you can do that within the with statement. The following two examplesare equivalent:

{% with foo = 42 %} {{ foo }}{% endwith %}{% with %} {% set foo = 42 %} {{ foo }}{% endwith %}

An important note on scoping here. In Jinja versions before 2.9 thebehavior of referencing one variable to another had some unintendedconsequences. In particular one variable could refer to another definedin the same with block’s opening statement. This caused issues with thecleaned up scoping behavior and has since been improved. In particularin newer Jinja versions the following code always refers to the variablea from outside the with block:

{% with a={}, b=a.attribute %}...{% endwith %}

In earlier Jinja versions the b attribute would refer to the results ofthe first attribute. If you depend on this behavior you can rewrite it touse the set tag:

{% with a={} %} {% set b = a.attribute %}{% endwith %}

Extension

In older versions of Jinja (before 2.9) it was required to enable thisfeature with an extension. It’s now enabled by default.

Autoescape Overrides¶

Changelog

New in version 2.4.

If you want you can activate and deactivate the autoescaping from withinthe templates.

Example:

{% autoescape true %} Autoescaping is active within this block{% endautoescape %}{% autoescape false %} Autoescaping is inactive within this block{% endautoescape %}

After an endautoescape the behavior is reverted to what it was before.

Extension

In older versions of Jinja (before 2.9) it was required to enable thisfeature with an extension. It’s now enabled by default.