Snippet to populate Gravity Forms dropdown field with values from custom taxonomy

gf-populate-dropdown.php

<?php

// Replace 8 with your form ID
add_filter( 'gform_pre_render_8', 'populate_region_field' );
add_filter( 'gform_pre_validation_8', 'populate_region_field' );
add_filter( 'gform_pre_submission_filter_8', 'populate_region_field' );
add_filter( 'gform_admin_pre_render_8', 'populate_region_field' );

function populate_region_field( $form ) {    
	foreach ( $form['fields'] as &$field ) {
		if ( strpos( $field->cssClass, 'regions' ) === false ) { // Replace 'regions' with your field class name
				continue;
		}

		$choices = array();

		$regions = get_terms( array(
				'taxonomy' => 'region', // Replace with your custom taxonomy
				'posts_per_page' => -1,
				'hide_empty' => false
		) );

		foreach ( $regions as $region ) {
				$regionName = $region->name;
				$choices[] = array( 'text' => html_entity_decode($regionName), 'value' => html_entity_decode($regionName), 'isSelected' => false );
		}

		$field->placeholder = 'Select Region(s)';
		$field->choices = $choices;
	}
	return $form;
}

?>