How do I get the site url from a Block (within the block editor)

Question

I have a block in which I'd like to display a link based on the site url. So for example, when the user enters "Futuristic", the link will display as https://my-site.com/futuristic/

I've looked at REST API /settings/ endpoint, which is supposed to include a url field, but it doesn't (at least on the two different sites I tried). Perhaps this is because I've got WP set up as multisite. There still should be a way to access the current site's url I'm sure.

I've looked into what wp.data.select() can provide in the various namespaces, but I don't see anything that would include the site url.

I tried looking at output of wp.data.select('core').getSite() (see Hardeep's suggestion), but mine has no url property and looks like this:

{ 
  date_format: "F j, Y"
  default_category: 1
  default_comment_status: "open"
​  default_ping_status: "open"
​  default_post_format: "0"
​  description: ""
​  language: ""
​  posts_per_page: 10
​  start_of_week: 0
​  time_format: "g:i a"
​  timezone: "America/New_York"
​  title: "The Name of My Site"
​  use_smilies: true
}

I suspect the difference has to do with Multisite being enabled, but not sure.

Answer 1

Perhaps this is because I've got WP set up as multisite.

Yes, that's right, WordPress disables the siteurl (and also admin_email) settings on a Multisite — see register_initial_settings() for the source.

And I don't know why they disable those (two) settings, but you can explicitly enable them like so for the url/siteurl setting, which for example, would go in the theme's functions.php file:

// I copied this from the source..
register_setting(
    'general',
    'siteurl',
    array(
        'show_in_rest' => array(
            'name'   => 'url',
            'schema' => array(
                'format' => 'uri',
            ),
        ),
        'type'         => 'string',
        'description'  => __( 'Site URL.' ),
    )
);

Tried & tested working with WordPress 5.6.1 Multisite.

And also, wp.data.select( 'core' ).getSite() uses the Settings endpoint, so it's normal that the url property is missing by default on a Multisite.

Apart from that, getSite() caches the API results, so you'd need to reload the post editing screen/page in order for getSite() to give you the correct result, i.e. with the url property.

Answer 2

You can use wp_localize_script to pass anything you want, including site URL, to the editor as a global variable:

wp_localize_script(
    'script_name',
    'my_data',
    [
        'siteUrl' => get_site_url()
    ]
);

And then you can get it in the editor from window.my_data.siteUrl variable. Here script_name will be the script that you're enqueuing to the editor.

If you want to use the Data API, you can use wp.data.select( 'core' ).getSite(); and once the promise has resolved, you can use the URL property.