acf backend error handling

Question

I want to add custom error handling in acf backend. Here's my code:

function dfg_acf_validate_value( $valid, $value, $field, $input_name ) {

    // Bail early if value is already invalid.
    if( $valid !== true ) {
        return $valid;
    }

    if( $value != '30' and $value != 360 ) {
        return __( 'Please choose a valid type!' );
    }
    return $valid;
}

add_filter('acf/validate_value/name=dfg_service_type', 'dfg_acf_validate_value', 10, 4);

and in the backend when I choose something else (instead of 30 or 360) nothing happens. What's the reason for that?

I actually found that the hook is not fired. What's the reason for that?

function dfg_acf_validate_value( $valid, $value, $field, $input_name ) {
    
        if( $value != '30' ) {
            wp_mail('[email protected]', 'subject', 'message');
        }
        return $valid;
    }
    
    add_filter('acf/validate_value/name=dfg_service_type', 'dfg_acf_validate_value', 10, 4);

Answer 1

Lets walk though the acf/validate_value filter logically...

I'm assuming both of your code snippets are the same snippet, and you are not executing them together (as @Buttered_Toast pointed out).

Here is your code (see my added comments)

code below is assuming your dfg_service_type acf field is a number field...

/**
  * @param mixed $valid Whether or not the value is valid (boolean) or a custom error message (string).
  * @param mixed $value The field value.
  * @param array $field The field array containing all settings.
  * @param string $input_name The field DOM element name attribute.
  * @return bool|string
 */
function dfg_acf_validate_value($valid, $value, $field, $input_name) {

    // $valid true by default
    // but if $field['required'] is true then
    // valid is set to false if the value is empty, but allow 0 as a valid value
    if( $valid !== true ) {
        return $valid;
    }

    // set value if value is true and cast value to integer else set bool false
    $value = $value ? (int)$value : false;

    // here is your first snippet cleaned up...
    // you are simply just checking if value is not 30 and not 360
    // if anything but 30 or 360, the below condition will return __( 'Please choose a valid type!' ); 
    // is this your intention?  
    if( $value && ( $value !== 30 && $value !== 360 )) {
        return __( 'Please choose a valid type!' );
    }

    /**
        // here is another option to check if $value is greater than or equal too 30 and less than or equal too 360...
        if( $value && ( $value >= 30 && $value <= 360 )) {
            return __( 'Please choose a valid type!' );
        }
    */    

    // return valid and save value if above value conditions are not run
    return $valid;

}

// init the filter perform custom validation on the field’s `$value` before it is saved into the database.
// for all acf fields with the name `dfg_service_type`
add_filter('acf/validate_value/name=dfg_service_type', 'dfg_acf_validate_value', 10, 4);

Update

Let try and debug this.

Add some debug functions to the top of your functions.php which dumps then exits...

presuming your php version is 5.6+ so variable-length arg lists token works

<?php
/**
 * functions.php
 */

// dump and exit function
function dd(...$args) {
    dump(...$args);
    exit;
}

// dump
function dump(...$args) {
    foreach ($args as $dump) {
        echo '<pre class="dd">' . print_r($dump, true) . '</pre>';
    }
}

Then try this instead and save the field.

function dfg_acf_validate_value($valid, $value, $field, $input_name) {

  // test this is getting hit
  dd($valid, $value, $field, $input_name);    

}

add_filter('acf/validate_value/name=dfg_service_type', 'dfg_acf_validate_value', 10, 4);

If this returns dd results then the field validate value is getting hit.

Let me know how you get on and what is returned, and i'll try help some more.