django/docs/ref/templates/builtins.txt

.. _ref-templates-builtins:

==================================
Built-in template tags and filters
==================================

This document describes Django's built-in template tags and filters. It is
recommended that you use the :ref:`automatic documentation
<template-built-in-reference>`, if available, as this will also include
documentation for any custom tags or filters installed.

.. _ref-templates-builtins-tags:

Built-in tag reference
----------------------

.. highlightlang:: html+django

.. templatetag:: autoescape

autoescape
~~~~~~~~~~

.. versionadded:: 1.0

Control the current auto-escaping behavior. This tag takes either ``on`` or
``off`` as an argument and that determines whether auto-escaping is in effect
inside the block.

When auto-escaping is in effect, all variable content has HTML escaping applied
to it before placing the result into the output (but after any filters have
been applied). This is equivalent to manually applying the ``escape`` filter
to each variable.

The only exceptions are variables that are already marked as "safe" from
escaping, either by the code that populated the variable, or because it has had
the ``safe`` or ``escape`` filters applied.

.. templatetag:: block

block
~~~~~

Define a block that can be overridden by child templates. See
:ref:`Template inheritance <template-inheritance>` for more information.

.. templatetag:: comment

comment
~~~~~~~

Ignore everything between ``{% comment %}`` and ``{% endcomment %}``

.. templatetag:: csrf_token

csrf_token
~~~~~~~~~~

.. versionadded:: 1.1.2

In the Django 1.1.X series, this is a no-op tag that returns an empty string for
future compatibility purposes.  In Django 1.2 and later, it is used for CSRF
protection, as described in the documentation for :ref:`Cross Site Request
Forgeries <ref-contrib-csrf>`.

.. templatetag:: cycle

cycle
~~~~~

.. versionchanged:: 1.0
    Cycle among the given strings or variables each time this tag is encountered.

Within a loop, cycles among the given strings each time through the
loop::

    {% for o in some_list %}
        <tr class="{% cycle 'row1' 'row2' %}">
            ...
        </tr>
    {% endfor %}

You can use variables, too. For example, if you have two template variables,
``rowvalue1`` and ``rowvalue2``, you can cycle between their values like this::

    {% for o in some_list %}
        <tr class="{% cycle rowvalue1 rowvalue2 %}">
            ...
        </tr>
    {% endfor %}

Yes, you can mix variables and strings::

    {% for o in some_list %}
        <tr class="{% cycle 'row1' rowvalue2 'row3' %}">
            ...
        </tr>
    {% endfor %}

In some cases you might want to refer to the next value of a cycle from
outside of a loop. To do this, just give the ``{% cycle %}`` tag a name, using
"as", like this::

    {% cycle 'row1' 'row2' as rowcolors %}

From then on, you can insert the current value of the cycle wherever you'd like
in your template::

    <tr class="{% cycle rowcolors %}">...</tr>
    <tr class="{% cycle rowcolors %}">...</tr>

You can use any number of values in a ``{% cycle %}`` tag, separated by spaces.
Values enclosed in single (``'``) or double quotes (``"``) are treated as
string literals, while values without quotes are treated as template variables.

Note that the variables included in the cycle will not be escaped. This is
because template tags do not escape their content. If you want to escape the
variables in the cycle, you must do so explicitly::

    {% filter force_escape %}
        {% cycle var1 var2 var3 %}
    {% endfilter %}

For backwards compatibility, the ``{% cycle %}`` tag supports the much inferior
old syntax from previous Django versions. You shouldn't use this in any new
projects, but for the sake of the people who are still using it, here's what it
looks like::

    {% cycle row1,row2,row3 %}

In this syntax, each value gets interpreted as a literal string, and there's no
way to specify variable values. Or literal commas. Or spaces. Did we mention
you shouldn't use this syntax in any new projects?

.. templatetag:: debug

debug
~~~~~

Output a whole load of debugging information, including the current context and
imported modules.

.. templatetag:: extends

extends
~~~~~~~

Signal that this template extends a parent template.

This tag can be used in two ways:

   * ``{% extends "base.html" %}`` (with quotes) uses the literal value
     ``"base.html"`` as the name of the parent template to extend.

   * ``{% extends variable %}`` uses the value of ``variable``. If the variable
     evaluates to a string, Django will use that string as the name of the
     parent template. If the variable evaluates to a ``Template`` object,
     Django will use that object as the parent template.

See :ref:`template-inheritance` for more information.

.. templatetag:: filter

filter
~~~~~~

Filter the contents of the variable through variable filters.

Filters can also be piped through each other, and they can have arguments --
just like in variable syntax.

Sample usage::

    {% filter force_escape|lower %}
        This text will be HTML-escaped, and will appear in all lowercase.
    {% endfilter %}

.. templatetag:: firstof

firstof
~~~~~~~

Outputs the first variable passed that is not False, without escaping.

Outputs nothing if all the passed variables are False.

Sample usage::

    {% firstof var1 var2 var3 %}

This is equivalent to::

    {% if var1 %}
        {{ var1|safe }}
    {% else %}{% if var2 %}
        {{ var2|safe }}
    {% else %}{% if var3 %}
        {{ var3|safe }}
    {% endif %}{% endif %}{% endif %}

You can also use a literal string as a fallback value in case all
passed variables are False::

    {% firstof var1 var2 var3 "fallback value" %}

Note that the variables included in the firstof tag will not be escaped. This
is because template tags do not escape their content. If you want to escape
the variables in the firstof tag, you must do so explicitly::

    {% filter force_escape %}
        {% firstof var1 var2 var3 "fallback value" %}
    {% endfilter %}

.. templatetag:: for

for
~~~

Loop over each item in an array.  For example, to display a list of athletes
provided in ``athlete_list``::

    <ul>
    {% for athlete in athlete_list %}
        <li>{{ athlete.name }}</li>
    {% endfor %}
    </ul>

You can loop over a list in reverse by using ``{% for obj in list reversed %}``.

.. versionadded:: 1.0

If you need to loop over a list of lists, you can unpack the values
in each sub-list into individual variables. For example, if your context
contains a list of (x,y) coordinates called ``points``, you could use the
following to output the list of points::

    {% for x, y in points %}
        There is a point at {{ x }},{{ y }}
    {% endfor %}

This can also be useful if you need to access the items in a dictionary.
For example, if your context contained a dictionary ``data``, the following
would display the keys and values of the dictionary::

    {% for key, value in data.items %}
        {{ key }}: {{ value }}
    {% endfor %}

The for loop sets a number of variables available within the loop:

    ==========================  ================================================
    Variable                    Description
    ==========================  ================================================
    ``forloop.counter``         The current iteration of the loop (1-indexed)
    ``forloop.counter0``        The current iteration of the loop (0-indexed)
    ``forloop.revcounter``      The number of iterations from the end of the
                                loop (1-indexed)
    ``forloop.revcounter0``     The number of iterations from the end of the
                                loop (0-indexed)
    ``forloop.first``           True if this is the first time through the loop
    ``forloop.last``            True if this is the last time through the loop
    ``forloop.parentloop``      For nested loops, this is the loop "above" the
                                current one
    ==========================  ================================================

for ... empty
^^^^^^^^^^^^^

.. versionadded:: 1.1

The ``for`` tag can take an optional ``{% empty %}`` clause that will be
displayed if the given array is empty or could not be found::

    <ul>
    {% for athlete in athlete_list %}
        <li>{{ athlete.name }}</li>
    {% empty %}
        <li>Sorry, no athlete in this list!</li>
    {% endfor %}
    <ul>

The above is equivalent to -- but shorter, cleaner, and possibly faster
than -- the following::

    <ul>
      {% if athlete_list %}
        {% for athlete in athlete_list %}
          <li>{{ athlete.name }}</li>
        {% endfor %}
      {% else %}
        <li>Sorry, no athletes in this list.</li>
      {% endif %}
    </ul>

.. templatetag:: if

if
~~

The ``{% if %}`` tag evaluates a variable, and if that variable is "true" (i.e.
exists, is not empty, and is not a false boolean value) the contents of the
block are output::

    {% if athlete_list %}
        Number of athletes: {{ athlete_list|length }}
    {% else %}
        No athletes.
    {% endif %}

In the above, if ``athlete_list`` is not empty, the number of athletes will be
displayed by the ``{{ athlete_list|length }}`` variable.

As you can see, the ``if`` tag can take an optional ``{% else %}`` clause that
will be displayed if the test fails.

Boolean operators
^^^^^^^^^^^^^^^^^

``if`` tags may use ``and``, ``or`` or ``not`` to test a number of variables or
to negate a given variable::

    {% if athlete_list and coach_list %}
        Both athletes and coaches are available.
    {% endif %}

    {% if not athlete_list %}
        There are no athletes.
    {% endif %}

    {% if athlete_list or coach_list %}
        There are some athletes or some coaches.
    {% endif %}

    {% if not athlete_list or coach_list %}
        There are no athletes or there are some coaches (OK, so
        writing English translations of boolean logic sounds
        stupid; it's not our fault).
    {% endif %}

    {% if athlete_list and not coach_list %}
        There are some athletes and absolutely no coaches.
    {% endif %}

.. versionchanged:: 1.2

Use of both ``and`` and ``or`` clauses within the same tag is allowed, with
``and`` having higher precedence than ``or`` e.g.::

    {% if athlete_list and coach_list or cheerleader_list %}

will be interpreted like:

.. code-block:: python

    if (athlete_list and coach_list) or cheerleader_list

Use of actual brackets in the ``if`` tag is invalid syntax.  If you need them to
indicate precedence, you should use nested ``if`` tags.

.. versionadded:: 1.2


``if`` tags may also use the operators ``==``, ``!=``, ``<``, ``>``,
``<=``, ``>=`` and ``in`` which work as follows:


``==`` operator
^^^^^^^^^^^^^^^

Equality. Example::

    {% if somevar == "x" %}
      This appears if variable somevar equals the string "x"
    {% endif %}

``!=`` operator
^^^^^^^^^^^^^^^

Inequality. Example::

    {% if somevar != "x" %}
      This appears if variable somevar does not equal the string "x",
      or if somevar is not found in the context
    {% endif %}

``<`` operator
^^^^^^^^^^^^^^

Less than. Example::

    {% if somevar < 100 %}
      This appears if variable somevar is less than 100.
    {% endif %}

``>`` operator
^^^^^^^^^^^^^^

Greater than. Example::

    {% if somevar > 0 %}
      This appears if variable somevar is greater than 0.
    {% endif %}

``<=`` operator
^^^^^^^^^^^^^^^

Less than or equal to. Example::

    {% if somevar <= 100 %}
      This appears if variable somevar is less than 100 or equal to 100.
    {% endif %}

``>=`` operator
^^^^^^^^^^^^^^^

Greater than or equal to. Example::

    {% if somevar >= 1 %}
      This appears if variable somevar is greater than 1 or equal to 1.
    {% endif %}

``in`` operator
^^^^^^^^^^^^^^^

Contained within. This operator is supported by many Python containers to test
whether the given value is in the container.  The following are some examples of
how ``x in y`` will be interpreted::

    {% if "bc" in "abcdef" %}
      This appears since "bc" is a substring of "abcdef"
    {% endif %}

    {% if "hello" in greetings %}
      If greetings is a list or set, one element of which is the string
      "hello", this will appear.
    {% endif %}

    {% if user in users %}
      If users is a QuerySet, this will appear if user is an
      instance that belongs to the QuerySet.
    {% endif %}


The comparison operators cannot be 'chained' like in Python or in mathematical
notation. For example, instead of using::

    {% if a > b > c %}  (WRONG)

you should use::

    {% if a > b and b > c %}


Filters
^^^^^^^

You can also use filters in the ``if`` expression. For example::

    {% if messages|length >= 100 %}
       You have lots of messages today!
    {% endif %}

Complex expressions
^^^^^^^^^^^^^^^^^^^

All of the above can be combined to form complex expressions. For such
expressions, it can be important to know how the operators are grouped when the
expression is evaluated - that is, the precedence rules.  The precedence of the
operators, from lowest to highest, is as follows:

 * ``or``
 * ``and``
 * ``not``
 * ``in``
 * ``==``, ``!=``, ``<``, ``>``,``<=``, ``>=``

(This follows Python exactly). So, for example, the following complex if tag:

    {% if a == b or c == d and e %}

...will be interpreted as:

.. code-block:: python

    (a == b) or ((c == d) and e)

If you need different precedence, you will need to use nested if tags. Sometimes
that is better for clarity anyway, for the sake of those who do not know the
precedence rules.


.. templatetag:: ifchanged

ifchanged
~~~~~~~~~

Check if a value has changed from the last iteration of a loop.

The 'ifchanged' block tag is used within a loop. It has two possible uses.

1. Checks its own rendered contents against its previous state and only
   displays the content if it has changed. For example, this displays a list of
   days, only displaying the month if it changes::

        <h1>Archive for {{ year }}</h1>

        {% for date in days %}
            {% ifchanged %}<h3>{{ date|date:"F" }}</h3>{% endifchanged %}
            <a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
        {% endfor %}

2. If given a variable, check whether that variable has changed. For
   example, the following shows the date every time it changes, but
   only shows the hour if both the hour and the date has changed::

        {% for date in days %}
            {% ifchanged date.date %} {{ date.date }} {% endifchanged %}
            {% ifchanged date.hour date.date %}
                {{ date.hour }}
            {% endifchanged %}
        {% endfor %}

The ``ifchanged`` tag can also take an optional ``{% else %}`` clause that
will be displayed if the value has not changed::

        {% for match in matches %}
            <div style="background-color:
                {% ifchanged match.ballot_id %}
                    {% cycle "red" "blue" %}
                {% else %}
                    grey
                {% endifchanged %}
            ">{{ match }}</div>
        {% endfor %}

.. templatetag:: ifequal

ifequal
~~~~~~~

Output the contents of the block if the two arguments equal each other.

Example::

    {% ifequal user.id comment.user_id %}
        ...
    {% endifequal %}

As in the ``{% if %}`` tag, an ``{% else %}`` clause is optional.

The arguments can be hard-coded strings, so the following is valid::

    {% ifequal user.username "adrian" %}
        ...
    {% endifequal %}

It is only possible to compare an argument to template variables or strings.
You cannot check for equality with Python objects such as ``True`` or
``False``.  If you need to test if something is true or false, use the ``if``
tag instead.

.. versionadded:: 1.2
   An alternative to the ``ifequal`` tag is to use the :ttag:`if` tag and the ``==`` operator.

.. templatetag:: ifnotequal

ifnotequal
~~~~~~~~~~

Just like ``ifequal``, except it tests that the two arguments are not equal.

.. versionadded:: 1.2
   An alternative to the ``ifnotequal`` tag is to use the :ttag:`if` tag and the ``!=`` operator.

.. templatetag:: include

include
~~~~~~~

Loads a template and renders it with the current context. This is a way of
"including" other templates within a template.

The template name can either be a variable or a hard-coded (quoted) string,
in either single or double quotes.

This example includes the contents of the template ``"foo/bar.html"``::

    {% include "foo/bar.html" %}

This example includes the contents of the template whose name is contained in
the variable ``template_name``::

    {% include template_name %}

An included template is rendered with the context of the template that's
including it. This example produces the output ``"Hello, John"``:

    * Context: variable ``person`` is set to ``"john"``.
    * Template::

        {% include "name_snippet.html" %}

    * The ``name_snippet.html`` template::

        Hello, {{ person }}

See also: ``{% ssi %}``.

.. templatetag:: load

load
~~~~

Load a custom template tag set.

See :ref:`Custom tag and filter libraries <howto-custom-template-tags>` for more information.

.. templatetag:: now

now
~~~

Display the date, formatted according to the given string.

Uses the same format as PHP's ``date()`` function (http://php.net/date)
with some custom extensions.

Available format strings:

    ================  ========================================  =====================
    Format character  Description                               Example output
    ================  ========================================  =====================
    a                 ``'a.m.'`` or ``'p.m.'`` (Note that       ``'a.m.'``
                      this is slightly different than PHP's
                      output, because this includes periods
                      to match Associated Press style.)
    A                 ``'AM'`` or ``'PM'``.                     ``'AM'``
    b                 Month, textual, 3 letters, lowercase.     ``'jan'``
    B                 Not implemented.
    c                 ISO 8601 Format.                          ``2008-01-02 10:30:00.000123``
    d                 Day of the month, 2 digits with           ``'01'`` to ``'31'``
                      leading zeros.
    D                 Day of the week, textual, 3 letters.      ``'Fri'``
    f                 Time, in 12-hour hours and minutes,       ``'1'``, ``'1:30'``
                      with minutes left off if they're zero.
                      Proprietary extension.
    F                 Month, textual, long.                     ``'January'``
    g                 Hour, 12-hour format without leading      ``'1'`` to ``'12'``
                      zeros.
    G                 Hour, 24-hour format without leading      ``'0'`` to ``'23'``
                      zeros.
    h                 Hour, 12-hour format.                     ``'01'`` to ``'12'``
    H                 Hour, 24-hour format.                     ``'00'`` to ``'23'``
    i                 Minutes.                                  ``'00'`` to ``'59'``
    I                 Not implemented.
    j                 Day of the month without leading          ``'1'`` to ``'31'``
                      zeros.
    l                 Day of the week, textual, long.           ``'Friday'``
    L                 Boolean for whether it's a leap year.     ``True`` or ``False``
    m                 Month, 2 digits with leading zeros.       ``'01'`` to ``'12'``
    M                 Month, textual, 3 letters.                ``'Jan'``
    n                 Month without leading zeros.              ``'1'`` to ``'12'``
    N                 Month abbreviation in Associated Press    ``'Jan.'``, ``'Feb.'``, ``'March'``, ``'May'``
                      style. Proprietary extension.
    O                 Difference to Greenwich time in hours.    ``'+0200'``
    P                 Time, in 12-hour hours, minutes and       ``'1 a.m.'``, ``'1:30 p.m.'``, ``'midnight'``, ``'noon'``, ``'12:30 p.m.'``
                      'a.m.'/'p.m.', with minutes left off
                      if they're zero and the special-case
                      strings 'midnight' and 'noon' if
                      appropriate. Proprietary extension.
    r                 RFC 2822 formatted date.                  ``'Thu, 21 Dec 2000 16:01:07 +0200'``
    s                 Seconds, 2 digits with leading zeros.     ``'00'`` to ``'59'``
    S                 English ordinal suffix for day of the     ``'st'``, ``'nd'``, ``'rd'`` or ``'th'``
                      month, 2 characters.
    t                 Number of days in the given month.        ``28`` to ``31``
    T                 Time zone of this machine.                ``'EST'``, ``'MDT'``
    u                 Microseconds.                             ``0`` to ``999999``
    U                 Seconds since the Unix Epoch
                      (January 1 1970 00:00:00 UTC).
    w                 Day of the week, digits without           ``'0'`` (Sunday) to ``'6'`` (Saturday)
                      leading zeros.
    W                 ISO-8601 week number of year, with        ``1``, ``53``
                      weeks starting on Monday.
    y                 Year, 2 digits.                           ``'99'``
    Y                 Year, 4 digits.                           ``'1999'``
    z                 Day of the year.                          ``0`` to ``365``
    Z                 Time zone offset in seconds. The          ``-43200`` to ``43200``
                      offset for timezones west of UTC is
                      always negative, and for those east of
                      UTC is always positive.
    ================  ========================================  =====================

Example::

    It is {% now "jS F Y H:i" %}

Note that you can backslash-escape a format string if you want to use the
"raw" value. In this example, "f" is backslash-escaped, because otherwise
"f" is a format string that displays the time. The "o" doesn't need to be
escaped, because it's not a format character::

    It is the {% now "jS o\f F" %}

This would display as "It is the 4th of September".

.. templatetag:: regroup

regroup
~~~~~~~

Regroup a list of alike objects by a common attribute.

This complex tag is best illustrated by use of an example: say that ``people``
is a list of people represented by dictionaries with ``first_name``,
``last_name``, and ``gender`` keys:

.. code-block:: python

    people = [
        {'first_name': 'George', 'last_name': 'Bush', 'gender': 'Male'},
        {'first_name': 'Bill', 'last_name': 'Clinton', 'gender': 'Male'},
        {'first_name': 'Margaret', 'last_name': 'Thatcher', 'gender': 'Female'},
        {'first_name': 'Condoleezza', 'last_name': 'Rice', 'gender': 'Female'},
        {'first_name': 'Pat', 'last_name': 'Smith', 'gender': 'Unknown'},
    ]

...and you'd like to display a hierarchical list that is ordered by gender,
like this:

    * Male:
        * George Bush
        * Bill Clinton
    * Female:
        * Margaret Thatcher
        * Condoleezza Rice
    * Unknown:
        * Pat Smith

You can use the ``{% regroup %}`` tag to group the list of people by gender.
The following snippet of template code would accomplish this::

    {% regroup people by gender as gender_list %}

    <ul>
    {% for gender in gender_list %}
        <li>{{ gender.grouper }}
        <ul>
            {% for item in gender.list %}
            <li>{{ item.first_name }} {{ item.last_name }}</li>
            {% endfor %}
        </ul>
        </li>
    {% endfor %}
    </ul>

Let's walk through this example. ``{% regroup %}`` takes three arguments: the
list you want to regroup, the attribute to group by, and the name of the
resulting list. Here, we're regrouping the ``people`` list by the ``gender``
attribute and calling the result ``gender_list``.

``{% regroup %}`` produces a list (in this case, ``gender_list``) of
**group objects**. Each group object has two attributes:

    * ``grouper`` -- the item that was grouped by (e.g., the string "Male" or
      "Female").
    * ``list`` -- a list of all items in this group (e.g., a list of all people
      with gender='Male').

Note that ``{% regroup %}`` does not order its input! Our example relies on
the fact that the ``people`` list was ordered by ``gender`` in the first place.
If the ``people`` list did *not* order its members by ``gender``, the regrouping
would naively display more than one group for a single gender. For example,
say the ``people`` list was set to this (note that the males are not grouped
together):

.. code-block:: python

    people = [
        {'first_name': 'Bill', 'last_name': 'Clinton', 'gender': 'Male'},
        {'first_name': 'Pat', 'last_name': 'Smith', 'gender': 'Unknown'},
        {'first_name': 'Margaret', 'last_name': 'Thatcher', 'gender': 'Female'},
        {'first_name': 'George', 'last_name': 'Bush', 'gender': 'Male'},
        {'first_name': 'Condoleezza', 'last_name': 'Rice', 'gender': 'Female'},
    ]

With this input for ``people``, the example ``{% regroup %}`` template code
above would result in the following output:

    * Male:
        * Bill Clinton
    * Unknown:
        * Pat Smith
    * Female:
        * Margaret Thatcher
    * Male:
        * George Bush
    * Female:
        * Condoleezza Rice

The easiest solution to this gotcha is to make sure in your view code that the
data is ordered according to how you want to display it.

Another solution is to sort the data in the template using the ``dictsort``
filter, if your data is in a list of dictionaries::

    {% regroup people|dictsort:"gender" by gender as gender_list %}

.. templatetag:: spaceless

spaceless
~~~~~~~~~

Removes whitespace between HTML tags. This includes tab
characters and newlines.

Example usage::

    {% spaceless %}
        <p>
            <a href="foo/">Foo</a>
        </p>
    {% endspaceless %}

This example would return this HTML::

    <p><a href="foo/">Foo</a></p>

Only space between *tags* is removed -- not space between tags and text. In
this example, the space around ``Hello`` won't be stripped::

    {% spaceless %}
        <strong>
            Hello
        </strong>
    {% endspaceless %}

.. templatetag:: ssi

ssi
~~~

Output the contents of a given file into the page.

Like a simple "include" tag, ``{% ssi %}`` includes the contents of another
file -- which must be specified using an absolute path -- in the current
page::

    {% ssi /home/html/ljworld.com/includes/right_generic.html %}

If the optional "parsed" parameter is given, the contents of the included
file are evaluated as template code, within the current context::

    {% ssi /home/html/ljworld.com/includes/right_generic.html parsed %}

Note that if you use ``{% ssi %}``, you'll need to define
:setting:`ALLOWED_INCLUDE_ROOTS` in your Django settings, as a security measure.

See also: ``{% include %}``.

.. templatetag:: templatetag

templatetag
~~~~~~~~~~~

Output one of the syntax characters used to compose template tags.

Since the template system has no concept of "escaping", to display one of the
bits used in template tags, you must use the ``{% templatetag %}`` tag.

The argument tells which template bit to output:

    ==================  =======
    Argument            Outputs
    ==================  =======
    ``openblock``       ``{%``
    ``closeblock``      ``%}``
    ``openvariable``    ``{{``
    ``closevariable``   ``}}``
    ``openbrace``       ``{``
    ``closebrace``      ``}``
    ``opencomment``     ``{#``
    ``closecomment``    ``#}``
    ==================  =======

.. templatetag:: url

url
~~~

Returns an absolute URL (i.e., a URL without the domain name) matching a given
view function and optional parameters. This is a way to output links without
violating the DRY principle by having to hard-code URLs in your templates::

    {% url path.to.some_view arg1,arg2,name1=value1 %}

The first argument is a path to a view function in the format
``package.package.module.function``. Additional arguments are optional and
should be comma-separated values that will be used as positional and keyword
arguments in the URL. All arguments required by the URLconf should be present.

For example, suppose you have a view, ``app_views.client``, whose URLconf
takes a client ID (here, ``client()`` is a method inside the views file
``app_views.py``). The URLconf line might look like this:

.. code-block:: python

    ('^client/(\d+)/$', 'app_views.client')

If this app's URLconf is included into the project's URLconf under a path
such as this:

.. code-block:: python

    ('^clients/', include('project_name.app_name.urls'))

...then, in a template, you can create a link to this view like this::

    {% url app_views.client client.id %}

The template tag will output the string ``/clients/client/123/``.

.. versionadded:: 1.0

If you're using :ref:`named URL patterns <naming-url-patterns>`, you can
refer to the name of the pattern in the ``url`` tag instead of using the
path to the view.

Note that if the URL you're reversing doesn't exist, you'll get an
:exc:`NoReverseMatch` exception raised, which will cause your site to display an
error page.

.. versionadded:: 1.0

If you'd like to retrieve a URL without displaying it, you can use a slightly
different call::


    {% url path.to.view arg, arg2 as the_url %}

    <a href="{{ the_url }}">I'm linking to {{ the_url }}</a>

This ``{% url ... as var %}`` syntax will *not* cause an error if the view is
missing. In practice you'll use this to link to views that are optional::

    {% url path.to.view as the_url %}
    {% if the_url %}
      <a href="{{ the_url }}">Link to optional stuff</a>
    {% endif %}

.. versionadded:: 1.1

If you'd like to retrieve a namespaced URL, specify the fully qualified name::

    {% url myapp:view-name %}

This will follow the normal :ref:`namespaced URL resolution strategy
<topics-http-reversing-url-namespaces>`, including using any hints provided
by the context as to the current application.

.. templatetag:: widthratio

widthratio
~~~~~~~~~~

For creating bar charts and such, this tag calculates the ratio of a given value
to a maximum value, and then applies that ratio to a constant.

For example::

    <img src="bar.gif" height="10" width="{% widthratio this_value max_value 100 %}" />

Above, if ``this_value`` is 175 and ``max_value`` is 200, the image in the
above example will be 88 pixels wide (because 175/200 = .875; .875 * 100 = 87.5
which is rounded up to 88).

.. templatetag:: with

with
~~~~

.. versionadded:: 1.0

Caches a complex variable under a simpler name. This is useful when accessing
an "expensive" method (e.g., one that hits the database) multiple times.

For example::

    {% with business.employees.count as total %}
        {{ total }} employee{{ total|pluralize }}
    {% endwith %}

The populated variable (in the example above, ``total``) is only available
between the ``{% with %}`` and ``{% endwith %}`` tags.

.. _ref-templates-builtins-filters:

Built-in filter reference
-------------------------

.. templatefilter:: add

add
~~~

Adds the argument to the value.

For example::

    {{ value|add:"2" }}

If ``value`` is ``4``, then the output will be ``6``.

.. templatefilter:: addslashes

addslashes
~~~~~~~~~~

Adds slashes before quotes. Useful for escaping strings in CSV, for example.

.. templatefilter:: capfirst

capfirst
~~~~~~~~

Capitalizes the first character of the value.

.. templatefilter:: center

center
~~~~~~

Centers the value in a field of a given width.

.. templatefilter:: cut

cut
~~~

Removes all values of arg from the given string.

For example::

    {{ value|cut:" "}}

If ``value`` is ``"String with spaces"``, the output will be ``"Stringwithspaces"``.

.. templatefilter:: date

date
~~~~

Formats a date according to the given format.

Given format can be one of the predefined ones ``DATE_FORMAT``,
``DATETIME_FORMAT``, ``SHORT_DATE_FORMAT`` or ``SHORT_DATETIME_FORMAT``,
or a custom format, same as the `now`_ tag. Note that predefined formats may
vary depending on the current locale.

For example::

    {{ value|date:"D d M Y" }}

If ``value`` is a ``datetime`` object (e.g., the result of
``datetime.datetime.now()``), the output will be the string
``'Wed 09 Jan 2008'``.

When used without a format string::

    {{ value|date }}

...the formatting string defined in the :setting:`DATE_FORMAT` setting will be
used, without applying any localization.

.. templatefilter:: default

default
~~~~~~~

If value evaluates to ``False``, use given default. Otherwise, use the value.

For example::

    {{ value|default:"nothing" }}

If ``value`` is ``""`` (the empty string), the output will be ``nothing``.

.. templatefilter:: default_if_none

default_if_none
~~~~~~~~~~~~~~~

If (and only if) value is ``None``, use given default. Otherwise, use the
value.

Note that if an empty string is given, the default value will *not* be used.
Use the ``default`` filter if you want to fallback for empty strings.

For example::

    {{ value|default_if_none:"nothing" }}

If ``value`` is ``None``, the output will be the string ``"nothing"``.

.. templatefilter:: dictsort

dictsort
~~~~~~~~

Takes a list of dictionaries and returns that list sorted by the key given in
the argument.

For example::

    {{ value|dictsort:"name" }}

If ``value`` is:

.. code-block:: python

    [
        {'name': 'zed', 'age': 19},
        {'name': 'amy', 'age': 22},
        {'name': 'joe', 'age': 31},
    ]

then the output would be:

.. code-block:: python

    [
        {'name': 'amy', 'age': 22},
        {'name': 'joe', 'age': 31},
        {'name': 'zed', 'age': 19},
    ]

.. templatefilter:: dictsortreversed

dictsortreversed
~~~~~~~~~~~~~~~~

Takes a list of dictionaries and returns that list sorted in reverse order by
the key given in the argument. This works exactly the same as the above filter,
but the returned value will be in reverse order.

.. templatefilter:: divisibleby

divisibleby
~~~~~~~~~~~

Returns ``True`` if the value is divisible by the argument.

For example::

    {{ value|divisibleby:"3" }}

If ``value`` is ``21``, the output would be ``True``.

.. templatefilter:: escape

escape
~~~~~~

Escapes a string's HTML. Specifically, it makes these replacements:

    * ``<`` is converted to ``&lt;``
    * ``>`` is converted to ``&gt;``
    * ``'`` (single quote) is converted to ``&#39;``
    * ``"`` (double quote) is converted to ``&quot;``
    * ``&`` is converted to ``&amp;``

The escaping is only applied when the string is output, so it does not matter
where in a chained sequence of filters you put ``escape``: it will always be
applied as though it were the last filter. If you want escaping to be applied
immediately, use the ``force_escape`` filter.

Applying ``escape`` to a variable that would normally have auto-escaping
applied to the result will only result in one round of escaping being done. So
it is safe to use this function even in auto-escaping environments. If you want
multiple escaping passes to be applied, use the ``force_escape`` filter.

.. versionchanged:: 1.0
    Due to auto-escaping, the behavior of this filter has changed slightly.
    The replacements are only made once, after
    all other filters are applied -- including filters before and after it.

.. templatefilter:: escapejs

escapejs
~~~~~~~~

.. versionadded:: 1.0

Escapes characters for use in JavaScript strings. This does *not* make the
string safe for use in HTML, but does protect you from syntax errors when using
templates to generate JavaScript/JSON.

.. templatefilter:: filesizeformat

filesizeformat
~~~~~~~~~~~~~~

Format the value like a 'human-readable' file size (i.e. ``'13 KB'``,
``'4.1 MB'``, ``'102 bytes'``, etc).

For example::

    {{ value|filesizeformat }}

If ``value`` is 123456789, the output would be ``117.7 MB``.

.. templatefilter:: first

first
~~~~~

Returns the first item in a list.

For example::

    {{ value|first }}

If ``value`` is the list ``['a', 'b', 'c']``, the output will be ``'a'``.

.. templatefilter:: fix_ampersands

fix_ampersands
~~~~~~~~~~~~~~

.. versionchanged:: 1.0
    This is rarely useful as ampersands are now automatically escaped. See escape_ for more information.

Replaces ampersands with ``&amp;`` entities.

For example::

    {{ value|fix_ampersands }}

If ``value`` is ``Tom & Jerry``, the output will be ``Tom &amp; Jerry``.

.. templatefilter:: floatformat

floatformat
~~~~~~~~~~~

When used without an argument, rounds a floating-point number to one decimal
place -- but only if there's a decimal part to be displayed. For example:

============  ===========================  ========
``value``     Template                     Output
============  ===========================  ========
``34.23234``  ``{{ value|floatformat }}``  ``34.2``
``34.00000``  ``{{ value|floatformat }}``  ``34``
``34.26000``  ``{{ value|floatformat }}``  ``34.3``
============  ===========================  ========

If used with a numeric integer argument, ``floatformat`` rounds a number to
that many decimal places. For example:

============  =============================  ==========
``value``     Template                       Output
============  =============================  ==========
``34.23234``  ``{{ value|floatformat:3 }}``  ``34.232``
``34.00000``  ``{{ value|floatformat:3 }}``  ``34.000``
``34.26000``  ``{{ value|floatformat:3 }}``  ``34.260``
============  =============================  ==========

If the argument passed to ``floatformat`` is negative, it will round a number
to that many decimal places -- but only if there's a decimal part to be
displayed. For example:

============  ================================  ==========
``value``     Template                          Output
============  ================================  ==========
``34.23234``  ``{{ value|floatformat:"-3" }}``  ``34.232``
``34.00000``  ``{{ value|floatformat:"-3" }}``  ``34``
``34.26000``  ``{{ value|floatformat:"-3" }}``  ``34.260``
============  ================================  ==========

Using ``floatformat`` with no argument is equivalent to using ``floatformat``
with an argument of ``-1``.

.. templatefilter:: force_escape

force_escape
~~~~~~~~~~~~

.. versionadded:: 1.0

Applies HTML escaping to a string (see the ``escape`` filter for details).
This filter is applied *immediately* and returns a new, escaped string. This
is useful in the rare cases where you need multiple escaping or want to apply
other filters to the escaped results. Normally, you want to use the ``escape``
filter.

.. templatefilter:: get_digit

get_digit
~~~~~~~~~

Given a whole number, returns the requested digit, where 1 is the right-most
digit, 2 is the second-right-most digit, etc. Returns the original value for
invalid input (if input or argument is not an integer, or if argument is less
than 1). Otherwise, output is always an integer.

For example::

    {{ value|get_digit:"2" }}

If ``value`` is ``123456789``, the output will be ``8``.

.. templatefilter:: iriendcode

iriencode
~~~~~~~~~

Converts an IRI (Internationalized Resource Identifier) to a string that is
suitable for including in a URL. This is necessary if you're trying to use
strings containing non-ASCII characters in a URL.

It's safe to use this filter on a string that has already gone through the
``urlencode`` filter.

.. templatefilter:: join

join
~~~~

Joins a list with a string, like Python's ``str.join(list)``

For example::

    {{ value|join:" // " }}

If ``value`` is the list ``['a', 'b', 'c']``, the output will be the string
``"a // b // c"``.

.. templatefilter:: last

last
~~~~

.. versionadded:: 1.0

Returns the last item in a list.

For example::

    {{ value|last }}

If ``value`` is the list ``['a', 'b', 'c', 'd']``, the output will be the string
``"d"``.

.. templatefilter:: length

length
~~~~~~

Returns the length of the value. This works for both strings and lists.

For example::

    {{ value|length }}

If ``value`` is ``['a', 'b', 'c', 'd']``, the output will be ``4``.

.. templatefilter:: length_is

length_is
~~~~~~~~~

Returns ``True`` if the value's length is the argument, or ``False`` otherwise.

For example::

    {{ value|length_is:"4" }}

If ``value`` is ``['a', 'b', 'c', 'd']``, the output will be ``True``.

.. templatefilter:: linebreaks

linebreaks
~~~~~~~~~~

Replaces line breaks in plain text with appropriate HTML; a single
newline becomes an HTML line break (``<br />``) and a new line
followed by a blank line becomes a paragraph break (``</p>``).

For example::

    {{ value|linebreaks }}

If ``value`` is ``Joel\nis a slug``, the output will be ``<p>Joel<br />is a
slug</p>``.

.. templatefilter:: linebreaksbr

linebreaksbr
~~~~~~~~~~~~

Converts all newlines in a piece of plain text to HTML line breaks
(``<br />``).

.. templatefilter:: linenumbers

linenumbers
~~~~~~~~~~~

Displays text with line numbers.

.. templatefilter:: ljust

ljust
~~~~~

Left-aligns the value in a field of a given width.

**Argument:** field size

.. templatefilter:: lower

lower
~~~~~

Converts a string into all lowercase.

For example::

    {{ value|lower }}

If ``value`` is ``Still MAD At Yoko``, the output will be ``still mad at yoko``.

.. templatefilter:: make_list

make_list
~~~~~~~~~

Returns the value turned into a list. For an integer, it's a list of
digits. For a string, it's a list of characters.

For example::

    {{ value|make_list }}

If ``value`` is the string ``"Joel"``, the output would be the list
``[u'J', u'o', u'e', u'l']``. If ``value`` is ``123``, the output will be the
list ``[1, 2, 3]``.

.. templatefilter:: phone2numeric

phone2numeric
~~~~~~~~~~~~~

Converts a phone number (possibly containing letters) to its numerical
equivalent. For example, ``'800-COLLECT'`` will be converted to
``'800-2655328'``.

The input doesn't have to be a valid phone number. This will happily convert
any string.

.. templatefilter:: pluralize

pluralize
~~~~~~~~~

Returns a plural suffix if the value is not 1. By default, this suffix is ``'s'``.

Example::

    You have {{ num_messages }} message{{ num_messages|pluralize }}.

For words that require a suffix other than ``'s'``, you can provide an alternate
suffix as a parameter to the filter.

Example::

    You have {{ num_walruses }} walrus{{ num_walruses|pluralize:"es" }}.

For words that don't pluralize by simple suffix, you can specify both a
singular and plural suffix, separated by a comma.

Example::

    You have {{ num_cherries }} cherr{{ num_cherries|pluralize:"y,ies" }}.

.. templatefilter:: pprint

pprint
~~~~~~

A wrapper around `pprint.pprint`__ -- for debugging, really.

__ http://docs.python.org/library/pprint.html

.. templatefilter:: random

random
~~~~~~

Returns a random item from the given list.

For example::

    {{ value|random }}

If ``value`` is the list ``['a', 'b', 'c', 'd']``, the output could be ``"b"``.

.. templatefilter:: removetags

removetags
~~~~~~~~~~

Removes a space-separated list of [X]HTML tags from the output.

For example::

    {{ value|removetags:"b span"|safe }}

If ``value`` is ``"<b>Joel</b> <button>is</button> a <span>slug</span>"`` the
output will be ``"Joel <button>is</button> a slug"``.

.. templatefilter:: rjust

rjust
~~~~~

Right-aligns the value in a field of a given width.

**Argument:** field size

.. templatefilter:: safe

safe
~~~~

Marks a string as not requiring further HTML escaping prior to output. When
autoescaping is off, this filter has no effect.

.. templatefilter:: safeseq

safeseq
~~~~~~~

Applies the :tfilter:`safe` filter to each element of a sequence.  Useful in
conjunction with other filters that operate on sequences, such as
:tfilter:`join`.  For example::

    {{ some_list|safeseq|join:", " }}

You couldn't use the :tfilter:`safe` filter directly in this case, as it would
first convert the variable into a string, rather than working with the
individual elements of the sequence.

.. templatefilter:: slice

slice
~~~~~

Returns a slice of the list.

Uses the same syntax as Python's list slicing. See
http://diveintopython.org/native_data_types/lists.html#odbchelper.list.slice
for an introduction.

Example::

    {{ some_list|slice:":2" }}

.. templatefilter:: slugify

slugify
~~~~~~~

Converts to lowercase, removes non-word characters (alphanumerics and
underscores) and converts spaces to hyphens. Also strips leading and trailing
whitespace.

For example::

    {{ value|slugify }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"joel-is-a-slug"``.

.. templatefilter:: stringformat

stringformat
~~~~~~~~~~~~

Formats the variable according to the argument, a string formatting specifier.
This specifier uses Python string formatting syntax, with the exception that
the leading "%" is dropped.

See http://docs.python.org/library/stdtypes.html#string-formatting-operations
for documentation of Python string formatting

For example::

    {{ value|stringformat:"s" }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"Joel is a slug"``.

.. templatefilter:: striptags

striptags
~~~~~~~~~

Strips all [X]HTML tags.

For example::

    {{ value|striptags }}

If ``value`` is ``"<b>Joel</b> <button>is</button> a <span>slug</span>"``, the
output will be ``"Joel is a slug"``.

.. templatefilter:: time

time
~~~~

Formats a time according to the given format.

Given format can be the predefined one ``TIME_FORMAT``, or a custom format,
same as the `now`_ tag. Note that the predefined format is locale depending.

The time filter will only accept parameters in the format string that relate
to the time of day, not the date (for obvious reasons). If you need to
format a date, use the `date`_ filter.

For example::

    {{ value|time:"H:i" }}

If ``value`` is equivalent to ``datetime.datetime.now()``, the output will be
the string ``"01:23"``.

When used without a format string::

    {{ value|time }}

...the formatting string defined in the :setting:`TIME_FORMAT` setting will be
used, without aplying any localization.

.. templatefilter:: timesince

timesince
~~~~~~~~~

Formats a date as the time since that date (e.g., "4 days, 6 hours").

Takes an optional argument that is a variable containing the date to use as
the comparison point (without the argument, the comparison point is *now*).
For example, if ``blog_date`` is a date instance representing midnight on 1
June 2006, and ``comment_date`` is a date instance for 08:00 on 1 June 2006,
then ``{{ blog_date|timesince:comment_date }}`` would return "8 hours".

Comparing offset-naive and offset-aware datetimes will return an empty string.

Minutes is the smallest unit used, and "0 minutes" will be returned for any
date that is in the future relative to the comparison point.

.. templatefilter:: timeuntil

timeuntil
~~~~~~~~~

Similar to ``timesince``, except that it measures the time from now until the
given date or datetime. For example, if today is 1 June 2006 and
``conference_date`` is a date instance holding 29 June 2006, then
``{{ conference_date|timeuntil }}`` will return "4 weeks".

Takes an optional argument that is a variable containing the date to use as
the comparison point (instead of *now*). If ``from_date`` contains 22 June
2006, then ``{{ conference_date|timeuntil:from_date }}`` will return "1 week".

Comparing offset-naive and offset-aware datetimes will return an empty string.

Minutes is the smallest unit used, and "0 minutes" will be returned for any
date that is in the past relative to the comparison point.

.. templatefilter:: title

title
~~~~~

Converts a string into titlecase.

.. templatefilter:: truncatewords

truncatewords
~~~~~~~~~~~~~

Truncates a string after a certain number of words.

**Argument:** Number of words to truncate after

For example::

    {{ value|truncatewords:2 }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"Joel is ..."``.

.. templatefilter:: truncatewords_html

truncatewords_html
~~~~~~~~~~~~~~~~~~

Similar to ``truncatewords``, except that it is aware of HTML tags. Any tags
that are opened in the string and not closed before the truncation point, are
closed immediately after the truncation.

This is less efficient than ``truncatewords``, so should only be used when it
is being passed HTML text.

.. templatefilter:: unordered_list

unordered_list
~~~~~~~~~~~~~~

Recursively takes a self-nested list and returns an HTML unordered list --
WITHOUT opening and closing <ul> tags.

.. versionchanged:: 1.0
   The format accepted by ``unordered_list`` has changed to be easier to understand.

The list is assumed to be in the proper format. For example, if ``var`` contains
``['States', ['Kansas', ['Lawrence', 'Topeka'], 'Illinois']]``, then
``{{ var|unordered_list }}`` would return::

    <li>States
    <ul>
            <li>Kansas
            <ul>
                    <li>Lawrence</li>
                    <li>Topeka</li>
            </ul>
            </li>
            <li>Illinois</li>
    </ul>
    </li>

Note: the previous more restrictive and verbose format is still supported:
``['States', [['Kansas', [['Lawrence', []], ['Topeka', []]]], ['Illinois', []]]]``,

.. templatefilter:: upper

upper
~~~~~

Converts a string into all uppercase.

For example::

    {{ value|upper }}

If ``value`` is ``"Joel is a slug"``, the output will be ``"JOEL IS A SLUG"``.

.. templatefilter:: urlencode

urlencode
~~~~~~~~~

Escapes a value for use in a URL.

.. templatefilter:: urlize

urlize
~~~~~~

Converts URLs in plain text into clickable links.

Note that if ``urlize`` is applied to text that already contains HTML markup,
things won't work as expected. Apply this filter only to *plain* text.

For example::

    {{ value|urlize }}

If ``value`` is ``"Check out www.djangoproject.com"``, the output will be
``"Check out <a
href="http://www.djangoproject.com">www.djangoproject.com</a>"``.

.. templatefilter:: urlizetrunc

urlizetrunc
~~~~~~~~~~~

Converts URLs into clickable links, truncating URLs longer than the given
character limit.

As with urlize_, this filter should only be applied to *plain* text.

**Argument:** Length to truncate URLs to

For example::

    {{ value|urlizetrunc:15 }}

If ``value`` is ``"Check out www.djangoproject.com"``, the output would be
``'Check out <a
href="http://www.djangoproject.com">www.djangopr...</a>'``.

.. templatefilter:: wordcount

wordcount
~~~~~~~~~

Returns the number of words.

.. templatefilter:: wordwrap

wordwrap
~~~~~~~~

Wraps words at specified line length.

**Argument:** number of characters at which to wrap the text

For example::

    {{ value|wordwrap:5 }}

If ``value`` is ``Joel is a slug``, the output would be::

    Joel
    is a
    slug

.. templatefilter:: yesno

yesno
~~~~~

Given a string mapping values for true, false and (optionally) None,
returns one of those strings according to the value:

==========  ======================  ==================================
Value       Argument                Outputs
==========  ======================  ==================================
``True``    ``"yeah,no,maybe"``     ``yeah``
``False``   ``"yeah,no,maybe"``     ``no``
``None``    ``"yeah,no,maybe"``     ``maybe``
``None``    ``"yeah,no"``           ``"no"`` (converts None to False
                                    if no mapping for None is given)
==========  ======================  ==================================

Other tags and filter libraries
-------------------------------

Django comes with a couple of other template-tag libraries that you have to
enable explicitly in your ``INSTALLED_APPS`` setting and enable in your
template with the ``{% load %}`` tag.

django.contrib.humanize
~~~~~~~~~~~~~~~~~~~~~~~

A set of Django template filters useful for adding a "human touch" to data. See
:ref:`ref-contrib-humanize`.

django.contrib.markup
~~~~~~~~~~~~~~~~~~~~~

A collection of template filters that implement these common markup languages:

    * Textile
    * Markdown
    * ReST (ReStructured Text)

See :ref:`ref-contrib-markup`.

django.contrib.webdesign
~~~~~~~~~~~~~~~~~~~~~~~~

A collection of template tags that can be useful while designing a website,
such as a generator of Lorem Ipsum text. See :ref:`ref-contrib-webdesign`.