/docs/ref/templates/builtins.txt

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

This document describes Django's built-in template tags and filters. It is
recommended that you use the :doc:`automatic documentation
</ref/contrib/admin/admindocs>`, 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
~~~~~~~~~~

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. The block is closed with an ``endautoescape`` ending tag.

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.

Sample usage::

    {% autoescape on %}
        {{ body }}
    {% endautoescape %}

.. 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
~~~~~~~~~~

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 :doc:`Cross Site Request
Forgeries </ref/contrib/csrf>`.

.. templatetag:: cycle

cycle
~~~~~

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 by referencing the cycle name as a context
variable. If you want to move the cycle onto the next value, you use
the cycle tag again, using the name of the variable. So, the following
template::

    <tr>
        <td class="{% cycle 'row1' 'row2' as rowcolors %}">...</td>
        <td class="{{ rowcolors }}">...</td>
    </tr>
    <tr>
        <td class="{% cycle rowcolors %}">...</td>
        <td class="{{ rowcolors }}">...</td>
    </tr>

would output::

    <tr>
        <td class="row1">...</td>
        <td class="row1">...</td>
    </tr>
    <tr>
        <td class="row2">...</td>
        <td class="row2">...</td>
    </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. Any HTML or
Javascript code contained in the printed variable will be rendered
as-is, which could potentially lead to security issues.

If you need 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?

.. versionadded:: 1.3

By default, when you use the ``as`` keyword with the cycle tag, the
usage of ``{% cycle %}`` that declares the cycle will itself output
the first value in the cycle. This could be a problem if you want to
use the value in a nested loop or an included template. If you want to
just declare the cycle, but not output the first value, you can add a
``silent`` keyword as the last keyword in the tag. For example::

    {% for obj in some_list %}
        {% cycle 'row1' 'row2' as rowcolors silent %}
        <tr class="{{ rowcolors }}">{% include "subtemplate.html " %}</tr>
    {% endfor %}

This will output a list of ``<tr>`` elements with ``class``
alternating between ``row1`` and ``row2``; the subtemplate will have
access to ``rowcolors`` in it's context that matches the class of the
``<tr>`` that encloses it. If the ``silent`` keyword were to be
omitted, ``row1`` would be emitted as normal text, outside the
``<tr>`` element.

When the silent keyword is used on a cycle definition, the silence
automatically applies to all subsequent uses of the cycle tag. In,
the following template would output *nothing*, even though the second
call to ``{% cycle %}`` doesn't specify silent::

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

.. 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.
Any HTML or Javascript code contained in the printed variable will be
rendered as-is, which could potentially lead to security issues.

If you need 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 %}``.

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
^^^^^^^^^^^^^

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 %}

``not in`` operator
~~~~~~~~~~~~~~~~~~~~

Not contained within.  This is the negation of the ``in`` operator.


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:

.. code-block:: django

    {% 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::

        {{ greeting }}, {{ person|default:"friend" }}!

.. versionchanged:: 1.3
   Additional context and exclusive context.

You can pass additional context to the template using keyword arguments::

    {% include "name_snippet.html" with person="Jane" greeting="Hello" %}

If you want to only render the context with the variables provided (or even
no variables at all), use the ``only`` option::

    {% include "name_snippet.html" with greeting="Hi" only %}

.. note::
    The :ttag:`include` tag should be considered as an implementation of
    "render this subtemplate and include the HTML", not as "parse this
    subtemplate and include its contents as if it were part of the parent".
    This means that there is no shared state between included templates --
    each include is a completely independent rendering process.

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

.. templatetag:: load

load
~~~~

Load a custom template tag set.

For example, the following template would load all the tags and filters
registered in ``somelibrary`` and ``otherlibrary``::

    {% load somelibrary otherlibrary %}

.. versionchanged:: 1.3

You can also selectively load individual filters or tags from a library, using
the ``from`` argument. In this example, the template tags/filters named ``foo``
and ``bar`` will be loaded from ``somelibrary``::

    {% load foo bar from somelibrary %}

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

.. templatetag:: now

now
~~~

Display the current date and/or time, using a format according to the given
string. Such string can contain format specifiers characters as described
in the :tfilter:`date` filter section.

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 %}


Grouping on other properties
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Any valid template lookup is a legal grouping attribute for the regroup
tag, including methods, attributes, dictionary keys and list items. For
example, if the "gender" field is a foreign key to a class with
an attribute "description," you could use::

    {% regroup people by gender.description as gender_list %}

Or, if ``gender`` is a field with ``choices``, it will have a
:meth:`~django.db.models.Model.get_FOO_display` method available as an
attribute, allowing  you to group on the display string rather than the
``choices`` key::

    {% regroup people by get_gender_display as gender_list %}

``{{ gender.grouper }}`` will now display the value fields from the
``choices`` set rather than the keys.

.. 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 %}``.

.. admonition:: Forwards compatibility

    .. versionchanged:: 1.3

    In Django 1.5, the behavior of the :ttag:`ssi` template tag will
    change, with the first argument being made into a context
    variable, rather than being a special case unquoted constant. This
    will allow the :ttag:`ssi` tag to use a context variable as the
    value of the page to be included.

    In order to provide a forwards compatibility path, Django 1.3
    provides a future compatibility library -- ``future`` -- that
    implements the new behavior. To use this library, add a
    :ttag:`load` call at the top of any template using the :ttag:`ssi`
    tag, and wrap the first argument to the :ttag:`ssi` tag in quotes.
    For example::

        {% load ssi from future %}
        {% ssi '/home/html/ljworld.com/includes/right_generic.html' %}

    In Django 1.5, the unquoted constant behavior will be replaced
    with the behavior provided by the ``future`` tag library.
    Existing templates should be migrated to use the new syntax.

.. 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 path reference (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 v1 v2 %}

The first argument is a path to a view function in the format
``package.package.module.function``. Additional arguments are optional and
should be space-separated values that will be used as arguments in the URL.
The example above shows passing positional arguments. Alternatively you may
use keyword syntax::

    {% url path.to.some_view arg1=v1 arg2=v2 %}

Do not mix both positional and keyword syntax in a single call. 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/``.

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:`~django.core.urlresolvers.NoReverseMatch` exception raised, which will
cause your site to display an error page.

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 %}

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.

.. versionchanged:: 1.2

For backwards compatibility, the ``{% url %}`` tag also supports the
use of commas to separate arguments. 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::

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

This syntax doesn't support the use of literal commas, or equals
signs. Did we mention you shouldn't use this syntax in any new
projects?

.. admonition:: Forwards compatibility

    .. versionchanged:: 1.3

    In Django 1.5, the behavior of the :ttag:`url` template tag will
    change, with the first argument being made into a context
    variable, rather than being a special case unquoted constant. This
    will allow the :ttag:`url` tag to use a context variable as the
    value of the URL name to be reversed.

    In order to provide a forwards compatibility path, Django 1.3
    provides a future compatibility library -- ``future`` -- that
    implements the new behavior. To use this library, add a
    :ttag:`load` call at the top of any template using the :ttag:`url`
    tag, and wrap the first argument to the :ttag:`url` tag in quotes.
    For example::

        {% load url from future %}
        {% url 'myapp:view-name' %}

    The new library also drops support for the comma syntax for
    separating arguments to the :ttag:`url` template tag.

    In Django 1.5, the old behavior will be replaced with the behavior
    provided by the ``future`` tag library. Existing templates be
    migrated to use the new syntax.

.. 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
~~~~

.. versionchanged:: 1.3
   New keyword argument format and multiple variable assignments.

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

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

You can assign more than one context variable::

    {% with alpha=1 beta=2 %}
        ...
    {% endwith %}

.. note:: The previous more verbose format is still supported:
   ``{% with business.employees.count as total %}``

.. _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``.

.. versionchanged:: 1.2
   The following behavior didn't exist in previous Django versions.

This filter will first try to coerce both values to integers. If this fails,
it'll attempt to add the values together anyway. This will work on some data
types (strings, list, etc.) and fail on others. If it fails, the result will
be an empty string.

For example, if we have::

    {{ first|add:second }}

and ``first`` is ``[1, 2, 3]`` and ``second`` is ``[4, 5, 6]``, then the
output will be ``[1, 2, 3, 4, 5, 6]``.

.. warning::

    Strings that can be coerced to integers will be **summed**, not
    concatenated, as in the first example above.

.. templatefilter:: addslashes

addslashes
~~~~~~~~~~

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

For example::

    {{ value|addslashes }}

If ``value`` is ``"I'm using Django"``, the output will be ``"I\'m using Django"``.

.. templatefilter:: capfirst

capfirst
~~~~~~~~

Capitalizes the first character of the value.

For example::

    {{ value|capfirst }}

If ``value`` is ``"django"``, the output will be ``"Django"``.

.. templatefilter:: center

center
~~~~~~

Centers the value in a field of a given width.

For example::

    "{{ value|center:"15" }}"

If ``value`` is ``"Django"``, the output will be ``"     Django    "``.

.. 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.

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.                          ``2008-01-02T10:30:00.000123``
    d                 Day of the month, 2 digits with           ``'01'`` to ``'31'``
                      leading zeros.
    D                 Day of the week, textual, 3 letters.      ``'Fri'``
    E                 Month, locale specific alternative
                      representation usually used for long
                      date representation.                      ``'listopada'`` (for Polish locale, as opposed to ``'Listopad'``)
    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.
    ================  ========================================  =====================

.. versionadded:: 1.2

The ``c`` and ``u`` format specification characters were added in Django 1.2.

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'``.

The format passed can be one of the predefined ones :setting:`DATE_FORMAT`,
:setting:`DATETIME_FORMAT`, :setting:`SHORT_DATE_FORMAT` or
:setting:`SHORT_DATETIME_FORMAT`, or a custom format that uses the format
specifiers shown in the table above. Note that predefined formats may vary
depending on the current locale.

Assuming that :setting:`USE_L10N` is ``True`` and :setting:`LANGUAGE_CODE` is,
for example, ``"es"``, then for::

    {{ value|date:"SHORT_DATE_FORMAT" }}

the output would be the string ``"09/01/2008"`` (the ``"SHORT_DATE_FORMAT"``
format specifier for the ``es`` locale as shipped with Django is ``"d/m/Y"``).

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.

.. versionchanged:: 1.2
    Predefined formats can now be influenced by the current locale.

.. 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.

.. templatefilter:: escapejs

escapejs
~~~~~~~~

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.

For example::

    {{ value|escapejs }}

If ``value`` is ``"testing\r\njavascript \'string" <b>escaping</b>"``,
the output will be ``"testing\\u000D\\u000Ajavascript \\u0027string\\u0022 \\u003Cb\\u003Eescaping\\u003C/b\\u003E"``.

.. 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
~~~~~~~~~~~~~~

.. note::

    This is rarely useful as ampersands are 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
~~~~~~~~~~~~

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:: iriencode

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.

For example::

    {{ value|iriencode }}

If ``value`` is ``"?test=1&me=2"``, the output will be ``"?test=1&amp;me=2"``.

.. 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
~~~~

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>`…