Django Template Filters

Django Template Engine provides filters which are used to transform the values of variables and tag arguments. We have already discussed major Django Template Tags. Tags can't modify value of a variable whereas filters can be used for incrementing value of a variable or modifying it to one's own need.

Syntax

{{ variable_name | filter_name }}

Filters can be “chained.” The output of one filter is applied to the next. {{ text|escape|linebreaks }} is a common idiom for escaping text contents, then converting line breaks to <p> tags.

Example

{{ value | length }}

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

Major Template Filters in Django

This article revolves around various Django Template Filters one can use during a project. Filters transform the values of variables and tag arguments. Let's check some major filters.

add

1. It is used to add an argument to the value. Example

{{ value | add:"2" }}

1. If value is 4, then the output will be 6. This filter is used to increment a variable in django Templates.

addslashes

1. It is used to add slashes before quotes. Useful for escaping strings in CSV. Example

{{ value | addslashes }}

1. If value is "I'm Jai", the output will be "I\'m Jai".

capfirst

1. It is used to capitalize the first character of the value. If the first character is not a letter, this filter has no effect. Example

{{ value | capfirst }}

1. If value is "jai", the output will be "Jai".

center

1. It is used to center the value in a field of a given width. Example

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

1. If value is "Jai", the output will be " Jai ".

cut

1. It is used to remove all values of arg from the given string. Example

{{ value | cut:" " }}

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

date

1. It is used to format a date according to the given format. Example

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

1. If value is a datetime object (e.g., the result of datetime.datetime.now()), the output will be the string 'Thu 06 Feb 2020'. For More information and patterns visit here.

default

1. It is used to give a default value to a variable. If variable evaluates to False, it will use the default argument given else the variable value itself. Example

{{ value | default:"nothing" }}

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

dictsort

1. It takes a list of dictionaries and returns that list sorted by the key given in the argument. Example

{{ value | dictsort:"name" }}

1. If value is:

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

1. then the output would be:

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

divisibleby

1. It returns True if the value is divisible by the argument. Example

{{ value | divisibleby:"3" }}

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

escape

1. It is used to escape a string’s HTML. Specifically, it makes these replacements: 

< is converted to <
> is converted to >
' (single quote) is converted to &#x27;
" (double quote) is converted to "
& is converted to &

1. Example

{{ title | escape }}

filesizeformat

1. It is used to format the value like a ‘human-readable’ file size (i.e. '13 KB', '4.1 MB', '102 bytes', etc.). Example

{{ value | filesizeformat }}

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

first

1. It is used to return the first item in a list. Example

{{ value | first }}

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

join

1. It is used to join a list with a string, like Python’s str.join(list) Example

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

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

last

1. It is used to return the last item in a list. Example

{{ value | last }}

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

length

1. It is used to return the length of the value. This works for both strings and lists. Example

{{ value | length }}

1. If value is ['a', 'b', 'c', 'd'] or "abcd", the output will be 4.

linenumbers

1. It is used to display text with line numbers. Example

{{ value | linenumbers }}

1. If value is:

one
two
three

1. the output will be:

1. one
2. two
3. three

lower

1. It is used to converts a string into all lowercase. Example

{{ value | lower }}}

1. If value is My Name is Jai, the output will be my name is jai.

make_list

1. It is used to return the value turned into a list. For a string, it’s a list of characters. For an integer, the argument is cast to a string before creating a list. Example

{{ value | make_list }}

1. If value is the string "Naveen", the output would be the list ['N', 'a', 'v', 'e', 'e', 'n']. If value is 123, the output will be the list ['1', '2', '3'].

random

1. It is used to return a random item from the given list. Example

{{ value | random }}

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

slice

1. It is used to return a slice of the list. Example

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

1. If some_list is ['a', 'b', 'c'], the output will be ['a', 'b'].

slugify

1. It is used to convert to ASCII. It converts spaces to hyphens and removes characters that aren’t alphanumerics, underscores, or hyphens. Converts to lowercase. Also strips leading and trailing whitespace. Example

{{ value | slugify }}

1. If value is "Jai is a slug", the output will be "jai-is-a-slug".

time

1. It is used to format a time according to the given format. Example

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

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

timesince

1. It is used to format a date as the time since that date (e.g., “4 days, 6 hours”). Example

{{ blog_date | timesince:comment_date }}

1. 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 the following would return “8 hours”

title

1. It is used to convert a string into titlecase by making words start with an uppercase character and the remaining characters lowercase. This filter makes no effort to keep “trivial words” in lowercase. Example

{{ value | title }}

1. If value is "my FIRST post", the output will be "My First Post".

unordered_list

1. It is used to recursively take a self-nested list and returns an HTML unordered list – WITHOUT opening and closing <ul> tags. Example

{{ var | unordered_list }}

1. 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>
         </li>

upper

1. It is used to convert a string into all uppercase. Example

{{ value | upper }}

1. If value is "Jai is a slug", the output will be "JAI IS A SLUG".

wordcount

1. It is used to return the number of words. Example

{{ value | wordcount }}

1. If value is "jai is a slug", the output will be 4.