acf/schema/format_value/pre

Documentation Filters acf/schema/format_value/pre

Last updated Mar 31, 2026

Overview

Filter a field value before default formatting is applied.

Description

This filter allows you to modify or replace field values before ACF applies its default JSON-LD formatting. Return a non-null value to bypass the default formatting entirely.

Changelog

• Added in version 6.8.0

Parameters

apply_filters( 'acf/schema/format_value/pre', $pre_value, $value, $field_object, $field_type );

• $pre_value (mixed) Pre-formatted value, or null to use default formatting
• $value (mixed) The raw field value
• $field_object (array) The field object with settings
• $field_type (string) The field type name

Return

(mixed|null) The pre-formatted value, or null to use default formatting.

Example

This example provides custom duration formatting.

/**
 * Custom ISO 8601 duration formatting.
 *
 * @param mixed  $pre_value    Pre-formatted value or null.
 * @param mixed  $value        The raw value.
 * @param array  $field_object The field object.
 * @param string $field_type   The field type.
 * @return mixed Pre-formatted value or null.
 */
function my_acf_schema_duration_format( $pre_value, $value, $field_object, $field_type ) {
    $property = $field_object['schema_property'] ?? '';

    // Handle duration properties
    $duration_properties = array( 'prepTime', 'cookTime', 'totalTime', 'duration' );

    if ( in_array( $property, $duration_properties, true ) && is_numeric( $value ) ) {
        $hours   = floor( $value / 60 );
        $minutes = $value % 60;

        if ( $hours > 0 && $minutes > 0 ) {
            return sprintf( 'PT%dH%dM', $hours, $minutes );
        } elseif ( $hours > 0 ) {
            return sprintf( 'PT%dH', $hours );
        } else {
            return sprintf( 'PT%dM', $minutes );
        }
    }

    return $pre_value; // Use default formatting
}
add_filter( 'acf/schema/format_value/pre', 'my_acf_schema_duration_format', 10, 4 );

This example handles custom date formatting.

/**
 * Custom date formatting for events.
 *
 * @param mixed  $pre_value    Pre-formatted value or null.
 * @param mixed  $value        The raw value.
 * @param array  $field_object The field object.
 * @param string $field_type   The field type.
 * @return mixed Pre-formatted value or null.
 */
function my_acf_schema_event_dates( $pre_value, $value, $field_object, $field_type ) {
    $property = $field_object['schema_property'] ?? '';

    // Format event dates with timezone
    if ( in_array( $property, array( 'startDate', 'endDate' ), true ) && $value ) {
        $timestamp = strtotime( $value );
        if ( $timestamp ) {
            return date( 'c', $timestamp ); // ISO 8601 with timezone
        }
    }

    return $pre_value;
}
add_filter( 'acf/schema/format_value/pre', 'my_acf_schema_event_dates', 10, 4 );

Related

• Filters: acf/schema/format_value/name={field_name}
• Filters: acf/schema/output_format_choices
• Filters: acf/schema/format_value
• Filters: acf/schema/format_value/pre/name={field_name}
• Filters: acf/schema/format_value/pre/type={field_type}