Complete Guide: How to Use Advanced Custom Fields (ACF) Hooks

Advanced Custom Fields (ACF) is a WordPress plugin that simplifies the creation and management of custom fields (text, selects, repeaters, galleries, flexible content, etc.) through a visual interface. It allows you to store structured data associated with posts, users, taxonomies, or options, and provides hooks (filters and actions) to intercept their lifecycle: loading, rendering, validation, saving, and formatting.

Main Hooks

Filters

Below is a list of ACF’s main filters with a short description of their usage.

acf/load_field (+ name=/key=/type=)

• When: Before rendering the field in the admin.
• Parameters: array $field
• Returns: array $field
• Uses: Modify label, placeholder, choices, wrapper.

acf/prepare_field (+ name=/key=/type=)

• When: Before preparing the final field array.
• Parameters: array $field
• Returns: array $field
• Uses: Modify final attributes, disable field.

acf/load_value (+ name=/key=/type=)

• When: When loading the stored field value.
• Parameters: $value, $post_id, array $field
• Returns: $value
• Uses: Format the value before displaying it.

acf/update_value (+ name=/key=/type=)

• When: Before saving the field value.
• Parameters: $value, $post_id, array $field
• Returns: $value
• Uses: Validate or sanitize values.

acf/validate_value (+ name=/key=/type=)

• When: When validating a field value.
• Parameters: $valid, $value, $field, $input
• Returns: $valid
• Uses: Enforce custom validation requirements.

acf/format_value (+ name=/key=/type=)

• When: When formatting the value for frontend usage.
• Parameters: $value, $post_id, array $field
• Returns: $value
• Uses: Adjust presentation for templates.

Actions

acf/save_post

• When: After saving ACF fields.
• Parameters: $post_id
• Uses: Save extra info, sync external data.

acf/delete_value

• When: When an ACF value is deleted.
• Parameters: $post_id, $key
• Uses: Remove additional related data.

acf/render_field

• When: When rendering the field’s HTML.
• Parameters: array $field
• Uses: Add extra HTML or attributes.

acf/render_field_settings

• When: When rendering field settings in the admin.
• Parameters: array $field
• Uses: Add custom options to a field type.

acf/input/admin_enqueue_scripts

• When: When loading CSS/JS in admin for ACF fields.
• Uses: Enqueue custom scripts or styles.

Practical Examples

Case 1:

Save an ACF field into the author’s user meta using acf/save_post

 
Case 2:
Modify all select fields using acf/load_field/type=select

 
Case 3:
Format a numeric value on frontend with acf/format_value

 
Case 4:
Validate a required field using acf/validate_value

 
Case 5:
Add a CSS class using acf/prepare_field

 
Case 6:
Sanitize a URL before saving using acf/update_value

 
Case 7:
Modify a Flexible Content field using acf/load_field/type=flexible_content

 
Case 8:
Repeater — process subfields when saving using acf/save_post
 $row ) {
                $caption = isset( $row['field_sub_caption'] )
                    ? sanitize_text_field( $row['field_sub_caption'] )
                    : '';

                // Save individual captions as separate meta entries
                update_post_meta( $postId, "gallery_item_{$index}_caption", $caption );
            }
        }
    }
}

 
This guide walked you through ACF’s main hooks, explained the difference between filters and actions, and demonstrated practical examples for modifying fields, validating, sanitizing, formatting, and working with complex field types like repeater and flexible content. Use these snippets as a foundation and adapt them to your actual field names or keys.
 
 





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Guía completa: Cómo usar los hooks de Advanced Custom Fields (ACF)