Conditionally registering field on acf/update_value

• orangutangle

• February 4, 2019 at 11:34 pm

I have a scenario where I wish to register a field on an existing field group when a different repeater field is updated.

(Simplified) code below:

function my_field_registration( $value, $post_id, $field  ) {

    if ( $field['name'] == 'my_triggering_field' ) {
    	if ( $some_condition ) {
			$args = array(
				'key' => 'field_5c58230b9b9f6',
				'label' =>  'Field label',
				'name' => 'my_new_field_name',
				'type' => 'number',
				'parent' => 'group_5c3f080211566'
			);
			acf_add_local_field($args);
		}
    }

    return $value;
    
}

add_filter('acf/update_value', 'my_field_registration', 10, 3);

However, this doesn’t register the field, I assume because my_field_registration is not running in the acf/init hook.

But how then do I register a field conditionally when another field is updated?

• John Huebner

• February 5, 2019 at 12:15 am

You cannot do this on that hook. In order for a field to be registered it must be run on every page load, in other words the init (or acf/init) hook.

It would also be very difficult to do this on the init hook.

Your best option would be to use an acf/prepare_field filter for this field and not display it if a check, or only display it, based on a check of the other field value https://www.advancedcustomfields.com/resources/acf-prepare_field/

• orangutangle

• February 5, 2019 at 12:27 am

I should clarify that I want the registered field to appear in the admin UI.

Should I be creating the field as an acf-field custom post type in the database?

• John Huebner

• February 5, 2019 at 12:34 am

I assumed this was to show the field in the admin. acf/prepare_field is called just before the field is shown in the admin and can be used to not show a field by returning false. You register the field as normal than you create a filter and in the filter you check the value of the other field and then you return the field or FALSE depending on that check.

• orangutangle

• February 5, 2019 at 1:51 am

Thanks for your suggestion John, but that would require me to know all possible field names in advance (so I could hide/show the correct one conditionally). There are infinite possibilities in my case.

What about using acf_update_field to write the field to the database? From includes/api-field.php:

/*
*  acf_update_field
*
*  This function will update a field into the DB.
*  The returned field will always contain an ID
*
*  @type	function
*  @date	1/10/13
*  @since	5.0.0
*
*  @param	$field (array)
*  @return	$field (array)
*/

function acf_update_field( $field = false, $specific = false )

I could construct a field object and call this function perhaps?

• orangutangle

• February 5, 2019 at 2:48 am

It turns out you can call acf_update_field with almost the same parameters as acf_add_local_field, except I just had to pass the parent as a post_id. Here’s the (simplified) code that I used:

function get_acf_group_id($group_name){
    global $wpdb;

    return $wpdb->get_var("
        SELECT ID
        FROM $wpdb->posts
        WHERE post_type='acf-field-group' AND post_excerpt='$group_name';
    ");
}

function my_field_registration( $value, $post_id, $field  ) {

    if ( $field['name'] == 'my_triggering_field' ) {
    	if ( $some_condition ) {
			$args = array(
				'key' => 'field_' . uniqid();,
				'label' =>  'Field label',
				'name' => 'my_new_field_name',
				'type' => 'number',
				'parent' => get_acf_group_id('my-field-group-name') // hyphenated!
			);
			acf_update_field($args);
		}
    }

    return $value;
    
}

add_filter('acf/update_value', 'my_field_registration', 10, 3);

This creates a field programmatically in the database which is editable in the admin.

• ybdigital

• June 20, 2020 at 8:02 am

Hi,

I am successfully using your function in order to create fields based on dynamic checkboxes present in a form.

Everything works fine expect the fields are not viewable in the backend option’s page until I go to the field group and manually save it. Only then the fields appear on the option’s page.

I am using the Json sync feature. Could this be the reason?

Do you have any idea as to why? Is there a way to programmatically save the group after the fields have been added?

I tried using acf_update_field_group() without success.

Thanks