set_query_var( string $query_var, mixed $value )

Sets the value of a query variable in the WP_Query class.

Parameters

$query_varstringrequired
Query variable key.
$valuemixedrequired
Query variable value.

Source

function set_query_var( $query_var, $value ) {
	global $wp_query;
	$wp_query->set( $query_var, $value );
}

Changelog

VersionDescription
2.2.0Introduced.

User Contributed Notes

  1. Skip to note 4 content

    One use case for this is to pass variable to template file when calling it with get_template_part().

    // When calling a template with get_template_part()
    set_query_var('my_form_id', 23);
    get_template_part('my-form-template');

    Now in you template you can then call it.

    // Inside my-form-template.php
    $my_form_id = get_query_var('my_form_id');
  2. Skip to note 5 content
    Anonymous User

    This is a way to pass variables to the called files.

    On the a.php file:

    $sample = 'a sample variable';
    $year = 2019;
    
    $arr = [
    	'sample' => $sample,
    	'year' => $year
    ];
    
    set_query_var( 'multiVar', $arr );
    get_template_part( 'b' );
    get_template_part( 'c' );

    On the b.php file:

    $arr = get_query_var( 'multiVar' );
    echo $arr['year']; // This will print out: 1995

    On the c.php file:

    $arr = get_query_var( 'multiVar' );
    echo $arr['sample']; // This will print out: a sample variable
  3. Skip to note 6 content

    To update examples and avoid spread of set_query_var() in recents projects.
    Lot of them continue to use set_query_var() for passing args/vars to a template with get_template_part().
    Since WordPress 5.5 (08/11/2020), think to use the $args third parameter to passed args to a template or a partial.

    // No example here as this is not the appropriate page
    But for example with get_template_part : https://developer.wordpress.org/reference/functions/get_template_part/#comment-4130

    Doc about passing arguments to template files :
    https://make.wordpress.org/core/2020/07/17/passing-arguments-to-template-files-in-wordpress-5-5/

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