Add wplf_allowed_additional_form_fields filter (#132)

Add wplf_allowed_additional_form_fields filter

Author: luizbills

README.md

@@ -176,6 +176,25 @@ Disabling additonal fields validation for all forms:
 add_filter( 'wplf_disable_validate_additional_fields' , '__return_true' );
 ```
 
+### Filter: wplf_allowed_additional_form_fields
+
+You can provide your own set of allowed field names, instead of disabling additional field validation entirely.
+
+#### Form specific hooks
+
+This filter supports form specific hooks:
+
+- `wplf_{form_id}_allowed_additional_form_fields`
+- `wplf_{form_slug}_allowed_additional_form_fields`
+
+These filters are only applied for the target form by ID or slug.
+
+Disabling additonal fields validation for all forms:
+
+```php
+add_filter( 'wplf_allowed_additional_form_fields' , ['dynamic-field-name'] );
+```
+
 ### Filter: wplf_dynamic_values
 
 Add or customize dynamic values available in forms.

inc/wplf-form-validation.php

@@ -101,8 +101,14 @@ function wplf_validate_additional_fields( $return ) {
   // add all default fields
   $default_fields = array( 'referrer', '_referrer_id', '_form_id', 'lang' );
 
+  // add all custom fields, form spesific filters
+  $custom_fields = array();
+  $custom_fields = apply_filters( "wplf_allowed_additional_form_fields", $custom_fields, $form );
+  $custom_fields = apply_filters( "wplf_{$form->ID}_allowed_additional_form_fields", $custom_fields, $form );
+  $custom_fields = apply_filters( "wplf_{$form->post_name}_allowed_additional_form_fields", $custom_fields, $form );
+
   // combine fields
-  $all_fields = array_merge( $form_fields, $default_fields );
+  $all_fields = array_merge( $form_fields, $custom_fields, $default_fields );
 
   // make sure fields from all_fields are the only ones present in $_POST
   $additional_fields = array();