Adding a user to a multisite blog using add_user_to_blog in WordPress

The add_user_to_blog function is a feature in WordPress that allows the addition of an existing user from the WordPress database to a specific blog within a multisite network. This function is part of the WordPress Multisite feature set, which facilitates the management of multiple WordPress sites from a single WordPress installation.

When a user is added to a blog through the add_user_to_blog function, they are given a specific role on that blog. The role can range from administrator, editor, author, contributor, to subscriber, each with different levels of access and capabilities.

The function is executed when there is a need to grant a user access to a blog without having to create a new user account. This can be useful in situations where a user needs to have access to multiple blogs within a network, but it is not practical or necessary to create separate user accounts for each blog.

It should be noted that the add_user_to_blog function only adds users to blogs. It does not create new users or modify existing user accounts. Also, it does not affect the user’s role or access on other blogs in the network.

Parameters Accepted by the add_user_to_blog Function

The WordPress add_user_to_blog function requires three parameters to work correctly. These are:

  • $blog_id (integer): This is a required parameter. It refers to the ID of the blog where the user is to be added.
  • $user_id (integer): This is also a mandatory parameter. It signifies the ID of the user who is being added to the blog.
  • $role (string): This required parameter denotes the user role in the blog.

Return Value of the add_user_to_blog Function

The add_user_to_blog function in WordPress returns either a boolean value of true or a WP_Error object. A return value of true indicates that the function executed successfully. On the other hand, a WP_Error object is returned if the user does not exist or could not be added to the blog for some reason.

Examples

How to Add a New User to a Blog

The most common usage of the add_user_to_blog function is to add a new user to a blog.

$user_id = 10;
$blog_id = 1;
$role = 'editor';

add_user_to_blog( $blog_id, $user_id, $role );

In this code snippet, we’re adding a user with the ID of 10 to the blog with the ID of 1. The user will have the role of ‘editor’ in the blog. The $user_id, $blog_id, and $role variables are used as parameters for the add_user_to_blog function.

How to Check if User Addition was Successful

The add_user_to_blog function can also be used with a control structure like an if statement to check if the user was successfully added to the blog.

$user_id = 10;
$blog_id = 1;
$role = 'editor';

if ( add_user_to_blog( $blog_id, $user_id, $role ) ) {
 echo "User added successfully.";
} else {
 echo "Failed to add user.";
}

In this code snippet, we’re adding a user to a blog and checking if the operation was successful. If the add_user_to_blog function returns true, we echo “User added successfully.” If it returns false, we echo “Failed to add user.”

How to Change a User’s Role in a Blog

Lastly, the add_user_to_blog function can be used to change a user’s role in a blog.

$user_id = 10;
$blog_id = 1;
$new_role = 'administrator';

add_user_to_blog( $blog_id, $user_id, $new_role );

In this code snippet, we’re changing the role of a user in a blog. The user with the ID of 10 will have their role changed to ‘administrator’ in the blog with the ID of 1. The $user_id, $blog_id, and $new_role variables are used as parameters for the add_user_to_blog function.

Conclusion

The add_user_to_blog function in WordPress is a tool that allows the addition of a user to a blog. It is particularly useful in situations where one needs to add a user to a specific blog in a multisite network. This function is executed by the system when a new user is registered or when an existing user is added to a blog. It is a critical part of the WordPress core and plays a significant role in user management within the platform.

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