Gravity Forms – Populate Multi-Select Field

August 25, 2021

Two examples provided comparing the regular select and multi-select field functions for Gravity Forms.

Place in functions.php. Update filter number with the form ID.

Simple Select field function

// meal plans - individual meals
add_filter( 'gform_pre_render_3', 'populate_select' );
add_filter( 'gform_pre_validation_3', 'populate_select' );
add_filter( 'gform_pre_submission_filter_3', 'populate_select' );
add_filter( 'gform_admin_pre_render_3', 'populate_select' );
function populate_select( $form ) {
 
    foreach( $form['fields'] as &$field )  {
        
        if ( $field->type != 'select' || strpos( $field->cssClass, 'custom-class' ) === false ) { // change to the type of field you are using (checkbox = select, radio = choices, etc)
            continue;
        }
       	 
        $args = array(
	    	'post_type'=>'post',
        	'posts_per_page'=>-1,
        );
        
        $posts = get_posts( $args );

        $choices = array();
		$input_id = 1;
        foreach ( $posts as $post ) {
            $choices[] = array( 
            	'text' => $post->post_title, 
            	'value' => $post->post_title 
            );
            
            $inputs[] = array( 
            	'label' => $post->post_title, 
            	'id' => "{$field->id}.{$input_id}"
            );
            
            $input_id++;
        }

        // update 'Select a Post' to whatever you'd like the instructive option to be
        $field->placeholder = 'Select';
        $field->choices = $choices;
        $field->inputs = $inputs;
		
    }
 
    return $form;
}

Multi-Select field function

// meal plans - individual meals
add_filter( 'gform_pre_render_8', 'populate_select_multi' );
add_filter( 'gform_pre_validation_8', 'populate_select_multi' );
add_filter( 'gform_pre_submission_filter_8', 'populate_select_multi' );
add_filter( 'gform_admin_pre_render_8', 'populate_select_multi' );
function populate_select_multi( $form ) {
 
    foreach( $form['fields'] as &$field )  {
        
        if ( $field->type != 'multiselect' || strpos( $field->cssClass, 'custom-class' ) === false ) { 
            continue;
        }
       	 
        $args = array(
	    	'post_type'=>'post',
        	'posts_per_page'=>-1,
        );
        
        $posts = get_posts( $args );

        $choices = array();
		
foreach ( $posts as $post ) {
            $choices[] = array( 
            	'text' => $post->post_title, 
            	'value' => $post->post_title,
            	'isSelected' => false
            );
        }

        // update 'Select a Post' to whatever you'd like the instructive option to be
        $field->placeholder = 'Select';
        $field->choices = $choices;
		
    }
 
    return $form;
}

Source.