Extending the vocabulary

Target group: Developers

Introduction

The TYPO3 schema extension ships type models and view helpers with their properties from the core vocabulary of the Schema.org definitions. However, there are several extensions, like Health and lifesciences or Autos. There are also pending types and properties available that enable schema.org to introduce terms on an experimental basis.

The embedding of these vocabulary extensions goes beyond the scope of this TYPO3 extension, as it will considerably increase the number of terms – while most of them are not used by the majority of users.

For your convenience there are separate extensions to extend the vocabulary available with the terms of the different sections. But if you only want to add only a few terms you are encouraged to add them on your own, especially pending terms.

Pending terms are experimental, after a certain time a term will be incorporated into the core vocabulary or dropped. This depends on the usage, adoption and discussions. To maintain backward-compatibility and to not break any pages, pending types are also not supplied by this extension.

But the vocabulary delivered with this extension can be extended according to your needs. This chapter describes the necessary steps to register additional properties to existing types or to introduce new types on your website.

Register additional properties

New in version 1.6.0.

You can use a PSR-14 event listener to add one ore more properties to one or more types. The chapter Register additional properties for a type describes how to register additional properties in detail.

Note

Approximately every 3-4 months a new version of the Schema.org definition is released. The extension adopts these changes in future releases. If you register a pending property for a type, this property can be included in the core vocabulary in a later version of this extension. However, it doesn’t do any harm to register a property that already exists.

Adding types

New in version 1.7.0.

You can add additional types for use in the API or as a WebPage type. As an example, in March 2020, Schema.org introduces a new VirtualLocation type related to the corona crisis, which also was also quickly adopted by Google. The type can be used as location in the Event type. So let’s start with this example.

1. Create the type model class

   The model class for a type defines the available properties. The model class for the VirtualLocation type may look like the following:

   <?php
   declare(strict_types=1);
   
   namespace Acme\LooneyTunes\Domain\Schema\Type;
   
   use Brotkrueml\Schema\Core\Model\AbstractType;
   
   final class VirtualLocation extends AbstractType
   {
      protected static $propertyNames = [
         'additionalType',
         'alternateName',
         'description',
         'disambiguatingDescription',
         'identifier',
         'image',
         'mainEntityOfPage',
         'name',
         'potentialAction',
         'sameAs',
         'subjectOf',
         'url',
      ];
   }
   

   That’s it. In the example, the class is stored in Classes/Domain/Schema/Type but you can choose any namespace. The protected static property $propertyNames contains the available Schema.org properties.

   Now you can use the VirtualLocation in your PHP code:

   $location = \Brotkrueml\Schema\Type\TypeFactory::createType('VirtualLocation');
   $location->setProperty('url', 'https://example.com/looney-tunes-webinar-12345/register');
   

   Important

   The class name must be named after the type name of Schema.org. In this example, the type is called VirtualLocation, so the class name is VirtualLocation.

2. Register the type model

   Now register the new type in the configuration file Configuration/TxSchema/TypeModels.php:

   <?php
   return [
      \Acme\LooneyTunes\Domain\Schema\Type\VirtualLocation::class,
   ];
   

   As it is not mandatory to register the class for usage in the API only, the registry is utilised in various places (like view helpers). Please also note that this may be mandatory in future versions of the TYPO3 schema extension.

   After changes to the TypeModels.php file the cache must be cleared.

   Note

   You can intentionally “override” a class model, e.g. the delivered Person class model with a customised one, but it is not recommended to do so. Instead, use the option to register additional properties.

3. Create the view helper

   If you have the need for a view helper with that type, you can create one easily:

   <?php
   declare(strict_types=1);
   
   namespace Acme\LooneyTunes\ViewHelpers\Type;
   
   use Brotkrueml\Schema\Core\ViewHelpers\AbstractTypeViewHelper;
   
   final class VirtualLocationViewHelper extends AbstractTypeViewHelper
   {
   }
   

   To use the schema namespace in Fluid templates also with your own view helpers add the following snippet to the ext_localconf.php file of your extension:

   $GLOBALS['TYPO3_CONF_VARS']['SYS']['fluid']['namespaces']['schema'][]
      = 'Acme\\LooneyTunes\\ViewHelpers';
   

   This way you don’t have to think about which namespace to use. And if the pending type is moved to the core vocabulary you have no need to touch your Fluid templates. Of course, feel free to use another namespace.

Important

Add the schema extension as a dependency to your extension. This ensures that your class models take precedence over the delivered models from the schema extension. This may be necessary if you define a pending type with pending properties (which you also use) to avoid breaks when the type is included into the core vocabulary but some properties aren’t.

Tip

Have a look into the schema_virtuallocation extension. It serves as a blueprint for adding own types and view helpers.

Add a new WebPage type

New in version 1.7.0.

If you are responsible for a medical website, the chances are high that you need the MedicalWebPage web page type, which is part of the Health schema.org extension.

Register this web page type so that it is available in the web page type list in the page properties. Simply follow the steps in the Adding types section. Registration of the type model is mandatory here.

Then mark your class as a WebPage type with the interface Brotkrueml\Schema\Core\Model\WebPageTypeInterface:

<?php
declare(strict_types=1);

namespace Acme\LooneyTunes\Domain\Schema\Type;

use Brotkrueml\Schema\Core\Model\AbstractType;
use Brotkrueml\Schema\Core\Model\WebPageTypeInterface;

final class MedicalWebPage extends AbstractType implements WebPageTypeInterface
{
   protected static $propertyNames = [
      // ... the properties ...
   ];
}

The new web page type can now be selected in the page properties:

MedicalWebPage in the list of available web page types

Add a new view helper

New in version 1.7.0.

As the API and thus the defined model class can be accessed in PHP, the use as a view helper in Fluid templates would also be nice sometimes. If you have the need for this, simply create a new view helper:

<?php
declare(strict_types=1);

namespace Acme\LooneyTunes\ViewHelpers\Type;

use Brotkrueml\Schema\Core\ViewHelpers\AbstractTypeViewHelper;

final class VirtualLocationViewHelper extends AbstractTypeViewHelper
{
}

The view helper must extend the Brotkrueml\Schema\Core\ViewHelpers\AbstractTypeViewHelper. The view helper must be named after the according type model. In the example the VirtualLocationViewHelper is connected to the VirtualLocation type model automatically.

Now you can use the view helper in a Fluid template (for example, when using the acme namespace):

<schema:type.event
   name="Daffy Duck talks about the new movie"
   startDate="2020-03-23T19:00">
      <acme:type.virtualLocation
         -as="location"
         url="https://example.com/looney-tunes-webinar-12345/register"
      />
</schema:type.event>

Every property name defined in the type model class is available as argument in the view helper.