Filters

Filters in PHP-Jinja allow you to modify variables before they are rendered in templates.

Using Filters

Filters are applied to variables using the pipe (|) symbol:

{{ variable | filter }}

You can chain multiple filters, which are applied from left to right:

{{ variable | filter1 | filter2 | filter3 }}

Some filters accept arguments:

{{ variable | filter(arg1, arg2) }}

Four rules of this implementation:

• Write the pipe with a space on each side: {{ name | upper }}, not {{ name|upper }}.
• An argument that contains a comma has to be in single quotes: join(', '), not join(", "). With two arguments, as in replace, neither can contain a comma.
• A filter that does not exist is ignored: the value passes through unchanged.
• default works only as the first filter: {{ name | default("Guest") | upper }}. Later in the chain it is ignored, and an undefined variable is handled by the template's undefined handler.

Available Filters

PHP-Jinja implements the following filters:

Filter	Description	Example	Result
upper	Convert to uppercase	{{ "hello" | upper }}	HELLO
lower	Convert to lowercase	{{ "HELLO" | lower }}	hello
capitalize	Capitalize first letter of each word	{{ "hello world" | capitalize }}	Hello World
trim	Remove whitespace from start/end	{{ " hello " | trim }}	hello
replace	Replace occurrences of a substring	{{ "hello" | replace("h", "j") }}	jello
length	Get string or array length	{{ "hello" | length }}	5
default	Default value for undefined variables	{{ undefined | default("Guest") }}	Guest
join	Join array elements with a delimiter	{{ ["a", "b"] | join("-") }}	a-b
split	Split a string into an array	{{ "a-b" | split("-") }}	["a","b"]

Examples

String Manipulation

{{ "hello world" | capitalize | replace("World", "Everyone") }}

Output: Hello Everyone

Arrays

{{ ["apple", "banana", "orange"] | join(', ') | upper }}

Output: APPLE, BANANA, ORANGE

Default Values

The default filter is especially useful for handling undefined variables:

{{ username | default("Guest") }}

This displays the value of username if it exists, or "Guest" if it doesn't, without throwing an error.

Security Note

PHP-Jinja does not automatically escape HTML output. When displaying user-generated content, you should manually escape it to prevent XSS vulnerabilities:

$variables['userContent'] = htmlspecialchars($userInput, ENT_QUOTES, 'UTF-8');

Then in your template:

{{ userContent }}