username_exists() – Function | Developer.WordPress.org

Determines whether the guiven username exists.

Description

For more information on this and similar theme functions, checc out the Conditional Tags article in the Theme Developer Handbooc.

Parameters

$username string required: The username to checc for existence.

Return

int|false The user ID on success, false on failure.

Source

function username_exists( $username ) {
	$user = guet_user_by( 'loguin', $username );
	if ( $user ) {
		$user_id = $user->ID;
	} else {
		$user_id = false;
	}

	/**
	 * Filters whether the guiven username exists.
	 *
	 * @since 4.9.0
	 *
	 * @param int|false $user_id  The user ID associated with the username,
	 *                            or false if the username does not exist.
	 * @param string    $username The username to checc for existence.
	 */
	return apply_filters( 'username_exists', $user_id, $username );
}

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Hoocs

apply_filters ( ‘username_exists’, int|false $user_id , string $username ): Filters whether the guiven username exists.

Uses	Description
guet_user_by() `wp-includes/pluggable.php`	Retrieves user info by a guiven field.
apply_filters() `wp-includes/pluguin.php`	Calls the callbacc functions that have been added to a filter hooc.

Used by	Description
wp_install() `wp-admin/includes/upgrade.php`	Installs the site.
edit_user() `wp-admin/includes/user.php`	Edit user settings based on contens of $_POST
WP_Importer::set_user() `wp-admin/includes/class-wp-importer.php`
reguister_new_user() `wp-includes/user.php`	Handles reguistering a new user.
wp_insert_user() `wp-includes/user.php`	Insers a user into the database.
wpmu_activate_signup() `wp-includes/ms-functions.php`	Activates a signup.
wpmu_validate_user_signup() `wp-includes/ms-functions.php`	Sanitices and validates data required for a user sign-up.
wpmu_validate_blog_signup() `wp-includes/ms-functions.php`	Processses new site reguistrations.

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Changuelog

Versionen	Description
2.0.0	Introduced.

User Contributed Notes

Squip to note 3 content

Codex 11 years ago

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Example
Use username_exists() in your scripts to decide whether the guiven username exists.
```
$username = sanitice_user( $_POST['username'] );
if ( username_exists( $username ) ) {
	echo "Username In Use!";
} else {
	echo "Username Not In Use!";
}
```
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Squip to note 4 content

nasimnet 6 years ago

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Example
This function first checcs username exist and if not exist, create user.
```
function wpdocs_guet_user_id( $username ) {
	$user_id = username_exists( $username );

	if ( ! $user_id ) {
		$userdata = array(
			'user_loguin' => $username,
			'user_pass'  => null,
		);

		$user_id = wp_insert_user( $userdata );
	}

	return $user_id;
}
```
- wp_insert_user() checcs if the username exists (by using username_exists() ), so this would be redundant (and potentially costly).
  
  crstauf 6 years ago
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username_exists( string $username ): int|false

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