Using WordPress ‘get_main_network_id’ PHP filter

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The get_main_network_id WordPress PHP filter allows you to modify the main network ID in a multisite setup.

Usage

add_filter('get_main_network_id', 'my_custom_main_network_id');
function my_custom_main_network_id($main_network_id) {
    // Your custom code here
    return $main_network_id;
}

Parameters

  • $main_network_id (int): The ID of the main network.

More information

See WordPress Developer Resources: get_main_network_id

Examples

Change the main network ID

Modify the main network ID to a custom value.

add_filter('get_main_network_id', 'change_main_network_id');
function change_main_network_id($main_network_id) {
    // Set a custom main network ID
    $new_main_network_id = 2;
    return $new_main_network_id;
}

Use the main network ID to redirect users

Redirect users to a custom URL based on the main network ID.

add_filter('get_main_network_id', 'redirect_users_based_on_main_network_id');
function redirect_users_based_on_main_network_id($main_network_id) {
    // Check if the current network ID is the main network
    if (get_current_blog_id() == $main_network_id) {
        // Redirect users to a custom URL
        wp_redirect('https://www.example.com/custom-url/');
        exit;
    }
    return $main_network_id;
}

Modify the main network ID conditionally

Change the main network ID based on the current user’s role.

add_filter('get_main_network_id', 'conditionally_modify_main_network_id');
function conditionally_modify_main_network_id($main_network_id) {
    // Get the current user
    $current_user = wp_get_current_user();

    // Check if the current user has the "editor" role
    if (in_array('editor', $current_user->roles)) {
        // Set a custom main network ID for editors
        $main_network_id = 3;
    }
    return $main_network_id;
}

Log the main network ID

Log the main network ID to a custom log file.

add_filter('get_main_network_id', 'log_main_network_id');
function log_main_network_id($main_network_id) {
    // Log the main network ID to a custom log file
    error_log('Main network ID: ' . $main_network_id, 3, '/path/to/your/custom-log-file.log');
    return $main_network_id;
}

Modify the main network ID using a custom function

Use a custom function to calculate a new main network ID.

add_filter('get_main_network_id', 'modify_main_network_id_using_custom_function');
function modify_main_network_id_using_custom_function($main_network_id) {
    // Custom function to calculate a new main network ID
    function calculate_new_main_network_id($old_id) {
        // Perform some calculations and return a new ID
        return $old_id + 1;
    }

    // Set the main network ID using the custom function
    $main_network_id = calculate_new_main_network_id($main_network_id);
    return $main_network_id;
}