Title: WP_Widget::get_field_id
Published: April 25, 2014
Last modified: August 20, 2026

---

# WP_Widget::get_field_id( string $field_name ): string

## In this article

 * [Description](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#description)
 * [Parameters](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#parameters)
 * [Return](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#return)
 * [Source](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#source)
 * [Changelog](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#changelog)

Constructs id attributes for use in [WP_Widget::form()](https://developer.wordpress.org/reference/classes/wp_widget/form/)
fields.

## 󠀁[Description](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#description)󠁿

This function should be used in form() methods to create id attributes for fields
to be saved by [WP_Widget::update()](https://developer.wordpress.org/reference/classes/wp_widget/update/).

## 󠀁[Parameters](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#parameters)󠁿

 `$field_name`stringrequired

Field name.

## 󠀁[Return](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#return)󠁿

 string ID attribute for `$field_name`.

## 󠀁[Source](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#source)󠁿

    ```php
    public function get_field_id( $field_name ) {
    	$field_name = str_replace( array( '[]', '[', ']' ), array( '', '-', '' ), $field_name );
    	$field_name = trim( $field_name, '-' );

    	return 'widget-' . $this->id_base . '-' . $this->number . '-' . $field_name;
    }
    ```

[View all references](https://developer.wordpress.org/reference/files/wp-includes/class-wp-widget.php/)
[View on Trac](https://core.trac.wordpress.org/browser/tags/7.1/src/wp-includes/class-wp-widget.php#L241)
[View on GitHub](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/class-wp-widget.php#L241-L246)

## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/wp_widget/get_field_id/?output_format=md#changelog)󠁿

| Version | Description | 
| [4.4.0](https://developer.wordpress.org/reference/since/4.4.0/) | Array format field IDs are now accepted. | 
| [2.8.0](https://developer.wordpress.org/reference/since/2.8.0/) | Introduced. |

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