Django Template Filters

Django Template Engine provides filters to transform the values of variables and tag arguments. Unlike template tags, which control logic or structure, filters are specifically used to modify or format variable values.

Syntax

{{ variable_name | filter_name }}

Filters can be "chained", meaning the output of one filter can be 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'], output will be 4.

Template Filters in Django

Django Template Filters transform the values of variables and tag arguments. Some most common template filters are listed below with example:

1. add

It is used to add an argument to the value.

Example:

{{ value | add:"2" }}

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

2. capfirst

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 }}

If value is "rahul", the output will be "Rahul".

3. date

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

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 'Thu 06 Feb 2020'.

4. default

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" }}

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

5. escape

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 & 

Example:

{{ title | escape }}

6. length

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

Example:

{{ value | length }}

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

7. lower

It is used to converts a string into all lowercase.

Example:

{{ value | lower }}

If value is My Name is Rahul, the output will be my name is rahul.

8. upper

It is used to convert a string into all uppercase.

Example:

{{ value | upper }}

If value is "Rahul Kumar", the output will be "RAHUL KUMAR".

9. title

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 }}

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

10. join

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

Example:

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

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

11. addslashes

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

Example:

{{ value | addslashes }}

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

12. center

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

Example:

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

If value is "Rahul", the output will be " Rahul ". The text "Rahul" is centered within a 15-character-wide field.

13. cut

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

Example:

{{ value | cut:" " }}

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

14. dictsort

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

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},
]

15. divisibleby

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

Example:

{{ value | divisibleby:"3" }}

If value is 21, the output would be True.

16. filesizeformat

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 }}

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

17. first

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

Example:

{{ value | first }}

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

18. last

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

Example:

{{ value | last }}

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

19. linenumbers

It is used to display text with line numbers.

Example:

{{ value | linenumbers }}

If value is:

one
two
three

the output will be:

1. one
2. two
3. three

20. make_list

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 }}

If value is the string "Rahul", the output would be the list ['R', 'a', 'h', 'u', 'l']. If value is 123, the output will be the list ['1', '2', '3'].

21. random

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

Example:

{{ value | random }}

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

22. slice

It is used to return a slice of the list.

Example:

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

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

23. slugify

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 }}

If value is "rahul is a slug", the output will be "rahul-is-a-slug".

24. time

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

Example:

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

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

25. timesince

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 }}

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”.

26. unordered_list

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 }}

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> 

27. wordcount

It is used to return the number of words.

Example:

{{ value | wordcount }}

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