Advanced Validation

Define custom validation rules and error messages based on the current screen location in the field’s UI.

Getting Started

In order to enable the Advanced Validation UI, you must enable the “Advanced Settings” setting in the field group and save it. The Advanced Settings UI will be available in all fields within that field group.

Available Locations

Choose the location screen where the validation rule should be applied. You can set multiple rules groups based on different locations.

  • Everywhere
  • Administration
  • Front-end

Available Functions

The UI comes with predefined functions that can be used out of the box.

Function namePHP Function
If valueif($value)
If value lengthif(strlen($value))
If count valueif(count($value))
If email existsif(email_exists($value))
If post type existsif(post_type_exists($value))
If taxonomy existsif(taxonomy_exists($value))
If term existsif(term_exists($value))
If username existsif(username_exists($value))
If is emailif(is_email($value))
If is user logged inif(is_user_logged_in())
If is arrayif(is_array($value))
If is stringif(is_string($value))
If is numericif(is_numeric($value))
If get post typeif(get_post_type($value))
If post id existsif(get_post_by_id($value))
If post slug existsif(get_post_by_slug($value))
If post title existsif(get_post_by_title($value))
If sanitize emailif(sanitize_email($value))
If sanitize file nameif(sanitize_file_name($value))
If sanitize html classif(sanitize_html_class($value))
If sanitize keyif(sanitize_key($value))
If sanitize metaif(sanitize_meta($value))
If sanitize mime typeif(sanitize_mime_type($value))
If sanitize optionif(sanitize_option($value))
If sanitize text fieldif(sanitize_text_field($value))
If sanitize titleif(sanitize_title($value))
If sanitize userif(sanitize_user($value))
If get user by idif(get_user_by('id', $value))
If get user by slugif(get_user_by('slug', $value))
If get user by emailif(get_user_by('email', $value))
If get user by loginif(get_user_by('login', $value))

Available Operators

The UI comes with predefined operators that can be used out of the box.

Doesn’t contain
Starts with
Doesn’t start with
Ends with
Doesn’t end with
Matches regex
Doesn’t match regex
== true
!= true
== false
!= false
== null
!= null
== “” (empty)
!= “” (empty)

Set Validation Rules in PHP

It is possible to add validation rules based on the screen location programmatically using the acf/validate_value hook combined with acfe_form_is_admin() and acfe_form_is_front() functions.

Note that this method doesn’t require to enable the “Advanced Settings” in the field group as it is directly executed in PHP. See ACF documentation. Usage example:

add_filter('acf/validate_value/name=my_field', 'my_acf_validate_my_field', 10, 4);
function my_acf_validate_my_field($valid, $value, $field, $input){
    // Admin only
        if(strlen($value) > 10)
            $valid = 'The value should contain less than 10 characters';
    // Front-end only
        if(strlen($value) > 30)
            $valid = 'The value should contain less than 30 characters';
    // return
    return $valid;