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Appendix E: Built-in Template Tags and Filters

Chapter 4 lists a number of the most useful built-in template tags and filters. However, Django ships with many more built-in tags and filters. This appendix covers them.

Built-in Tag Reference

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.

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.

block

Define a block that can be overridden by child templates. See Chapter 4 for more information on template inheritance.

comment

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

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:

<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.

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?

debug

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

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 Chapter 4 for more information on template inheritance.

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 %}

firstof

Outputs the first variable passed that is not False. Outputs nothing if all the passed variables are False.

Sample usage:

{% firstof var1 var2 var3 %}

This is equivalent to:

{% if var1 %}
    {{ var1 }}
{% else %}{% if var2 %}
    {{ var2 }}
{% else %}{% if var3 %}
    {{ var3 }}
{% 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" %}

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 (see Table E-1).

Table E-1. Variables Available Inside {% for %} Loops
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

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>

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.

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 %}

if tags don't allow and and or clauses within the same tag, because the order of logic would be ambiguous. For example, this is invalid:

{% if athlete_list and coach_list or cheerleader_list %}

If you need to combine and and or to do advanced logic, just use nested if tags. For example:

{% if athlete_list %}
    {% if coach_list or cheerleader_list %}
        We have athletes, and either coaches or cheerleaders!
    {% endif %}
{% endif %}

Multiple uses of the same logical operator are fine, as long as you use the same operator. For example, this is valid:

{% if athlete_list or coach_list or parent_list or teacher_list %}

ifchanged

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

The ifchanged 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 %}

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.

ifnotequal

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

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 %}.

load

Load a custom template tag set. See Chapter 9 for more information on custom template libraries.

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.

Table E-2 shows the available format strings.

Table E-2. Available Date Format Strings
Format character Description Example output
a 'a.m.' or 'p.m.' (Note that this is slightly different than PHP's output, because this includes periods to match Associated Press style.) 'a.m.'
A 'AM' or 'PM'. 'AM'
b Month, textual, 3 letters, lowercase. 'jan'
B Not implemented.  
d Day of the month, 2 digits with leading zeros. '01' to '31'
D Day of the week, textual, 3 letters. 'Fri'
f Time, in 12-hour hours and minutes, with minutes left off if they're zero. Proprietary extension. '1', '1:30'
F Month, textual, long. 'January'
g Hour, 12-hour format without leading zeros. '1' to '12'
G Hour, 24-hour format without leading zeros. '0' to '23'
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 zeros. '1' to '31'
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 style. Proprietary extension. 'Jan.', 'Feb.', 'March', 'May'
O Difference to Greenwich time in hours. '+0200'
P Time, in 12-hour hours, minutes and 'a.m.'/'p.m.', with minutes left off if they're zero and the special-case strings 'midnight' and 'noon' if appropriate. Proprietary extension. '1 a.m.', '1:30 p.m.', 'midnight', 'noon', '12:30 p.m.'
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 month, 2 characters. 'st', 'nd', 'rd' or 'th'
t Number of days in the given month. 28 to 31
T Time zone of this machine. 'EST', 'MDT'
U Not implemented.  
w Day of the week, digits without leading zeros. '0' (Sunday) to '6' (Saturday)
W ISO-8601 week number of year, with weeks starting on Monday. 1, 53
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 offset for timezones west of UTC is always negative, and for those east of UTC is always positive. -43200 to 43200

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".

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:

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):

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 %}

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 %}

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 ALLOWED_INCLUDE_ROOTS in your Django settings, as a security measure.

See also: {% include %}.

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.

See Table E-3 for the available arguments.

Table E-3. Available Arguments for templatetag Filter
Argument Outputs
openblock {%
closeblock %}
openvariable {{
closevariable }}
openbrace {
closebrace }
opencomment {#
closecomment #}

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:

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

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

('^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/.

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).

with

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.

Built-in Filter Reference

add

Adds the argument to the value.

For example:

{{ value|add:"2" }}

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

addslashes

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

capfirst

Capitalizes the first character of the value.

center

Centers the value in a field of a given width.

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".

date

Formats a date according to the given format (same as the {% now %} tag).

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 DATE_FORMAT setting will be used.

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.

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".

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:

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

then the output would be:

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

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.

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.

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.

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.

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.

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'.

fix_ampersands

Replaces ampersands with &amp; entities.

For example:

{{ value|fix_ampersands }}

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

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.

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.

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.

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.

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".

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".

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.

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.

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>.

linebreaksbr

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

linenumbers

Displays text with line numbers.

ljust

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

Argument: field size

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.

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].

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.

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_walrus|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" }}.

pprint

A wrapper around the Python standard library's pprint.pprint function -- for debugging, really.

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".

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".

rjust

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

Argument: field size

safe

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

safeseq

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

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

You couldn't use the 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.

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" }}

slugify

Converts to lowercase, removes non-word characters (only alphanumerics and underscores are kept) 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".

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".

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".

time

Formats a time according to the given format (same as the now tag). 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 TIME_FORMAT setting will be used.

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.

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.

title

Converts a string into titlecase.

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 ...".

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.

unordered_list

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

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>

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".

urlencode

Escapes a value for use in a URL.

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>".

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>'.

wordcount

Returns the number of words.

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

yesno

Given a string mapping values for True, False, and (optionally) None, returns one of those strings according to the value (see Table F-4).

Table E-4. Examples of the yesno Filter
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)
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