WP Forms custom validation

One useful code snippet for custom validation in WP Forms is to add a custom validation rule to check if a specific field value matches a predefined value. This can be useful in scenarios where you want to ensure that a user enters a specific value in a form field.

Here’s an example code snippet that demonstrates how to add a custom validation rule to a WP Forms field:

/**
 * Custom validation rule to check if a field value matches a predefined value.
 *
 * @param array $fields
 * @param array $entry
 * @param array $form_data
 *
 * @return array
 */
function wpsnippets_custom_validation_rule( $fields, $entry, $form_data ) {
    // Get the field value
    $field_value = $entry[ $fields['id'] ];

    // Define the predefined value
    $predefined_value = 'example';

    // Check if the field value matches the predefined value
    if ( $field_value !== $predefined_value ) {
        // Add an error message to the field
        $fields['failed_validation'] = true;
        $fields['errorMessage'] = 'Please enter the correct value.';
    }

    return $fields;
}
add_filter( 'wpforms_process_validate_field', 'wpsnippets_custom_validation_rule', 10, 3 );

In this code snippet, we define a custom validation rule using the wpforms_process_validate_field filter. The function wpsnippets_custom_validation_rule accepts three parameters: $fields, $entry, and $form_data. We retrieve the field value from the $entry array using the field ID, and compare it with a predefined value. If the values don’t match, we set the failed_validation flag to true and add an error message to the field.

You can modify the $predefined_value variable to match your specific requirement. This code snippet can be useful when you want to enforce a specific value in a form field, such as a confirmation field for password or email address.

Examples

Example 1: Custom validation for a WP Forms field

This example demonstrates how to add custom validation to a specific field in a WP Forms form. In this case, we will add a custom validation rule to check if the entered value is a valid email address.

function wpsnippets_custom_email_validation( $errors, $fields ) {
    if ( ! is_email( $fields['email'] ) ) {
        $errors['email']['invalid'] = 'Please enter a valid email address.';
    }
    return $errors;
}
add_filter( 'wpforms_process_validate_field', 'wpsnippets_custom_email_validation', 10, 2 );

Explanation:

• The wpforms_process_validate_field filter hook is used to add custom validation to a specific field in a WP Forms form.
• The wpsnippets_custom_email_validation function is hooked into this filter and receives two parameters: $errors (an array of validation errors) and $fields (an array of form field values).
• Inside the function, we check if the entered email address is valid using the is_email() function.
• If the email address is not valid, we add a custom error message to the $errors array for the ’email’ field.
• Finally, we return the modified $errors array.

Example 2: Custom validation for multiple fields

This example demonstrates how to add custom validation to multiple fields in a WP Forms form. In this case, we will add a custom validation rule to check if both the ‘name’ and ‘message’ fields are not empty.

function wpsnippets_custom_fields_validation( $errors, $fields ) {
    if ( empty( $fields['name'] ) ) {
        $errors['name']['empty'] = 'Please enter your name.';
    }
    if ( empty( $fields['message'] ) ) {
        $errors['message']['empty'] = 'Please enter a message.';
    }
    return $errors;
}
add_filter( 'wpforms_process_validate_field', 'wpsnippets_custom_fields_validation', 10, 2 );

Explanation:

• Similar to the previous example, we use the wpforms_process_validate_field filter hook to add custom validation to multiple fields in a WP Forms form.
• The wpsnippets_custom_fields_validation function is hooked into this filter and receives the $errors and $fields parameters.
• Inside the function, we check if the ‘name’ field is empty and add a custom error message to the $errors array if it is.
• Similarly, we check if the ‘message’ field is empty and add a custom error message if it is.
• Finally, we return the modified $errors array.

Example 3: Custom validation with conditional logic

This example demonstrates how to add custom validation with conditional logic to a WP Forms form. In this case, we will add a custom validation rule to check if a specific field is required based on the value of another field.

function wpsnippets_custom_conditional_validation( $errors, $fields ) {
    if ( $fields['country'] === 'USA' && empty( $fields['zipcode'] ) ) {
        $errors['zipcode']['empty'] = 'Please enter a ZIP code.';
    }
    return $errors;
}
add_filter( 'wpforms_process_validate_field', 'wpsnippets_custom_conditional_validation', 10, 2 );

Explanation:

• Again, we use the wpforms_process_validate_field filter hook to add custom validation to a WP Forms form.
• The wpsnippets_custom_conditional_validation function is hooked into this filter and receives the $errors and $fields parameters.
• Inside the function, we check if the value of the ‘country’ field is ‘USA’ and if the ‘zipcode’ field is empty.
• If both conditions are met, we add a custom error message to the $errors array for the ‘zipcode’ field.
• Finally, we return the modified $errors array.