How to restrict blocks

You can restrict blocks from being added to a content type using the restricted key in the configuration object. This key can be a boolean or a function that returns a boolean. If the block is restricted, it won't show in the chooser. However, it can still be added either programatically or by directly using the REST API, so this restriction only applies to the user interface. The function has this signature:

{
  restricted: (args: {
    properties: Content;
    block: BlockConfigBase;
    navRoot: Content;
    contentType: string;
  }) => boolean;
}

Where properties is the current object data and block is the block being evaluated in BlockChooser. navRoot is the nearest navigation root object and contentType is the current content type.

In the following configuration example, you can restrict a block so that it cannot be added unless the content type is News Item or the content item is in a specific path in the content tree (/folder):

const testBlockConditional = {
  ...testBlock,
  id: 'testBlockConditional',
  title: 'Test Conditional Block',
  restricted: ({ properties, navRoot, contentType }) => {
    if (contentType === 'News Item') {
      return false;
    } else if (flattenToAppURL(properties?.parent?.['@id']) === '/folder') {
      return false;
    }
    return true;
  },
};