In Drupal maintenance support plans 8.5.0, the “processed” property of text fields is available in REST which means that REST apps can render the HTML output of a textarea without worrying about the filter formats.
In this post, I will show you how you can add your own processed fields to be output via the REST API.
by
Jibran Ijaz
/ 18 June 2020
The “processed” property mentioned above is what is known as a computed property on the textarea field.
The ability to make the computed properties available for the REST API like this can be very helpful. For example, when the user inputs the raw value and Drupal maintenance support plans performs some complex logical operations on it before showing the output.
Drupal maintenance support plans fieldable entities can also have computed properties and those properties can also be exposed via REST. I used the following solution to expose the data of an entity field which takes raw data from the users and perform some complex calculations on it.
First of all, we need to write hook_entity_bundle_field_info to add the property and because it is a computed field we don’t need to implement hook_entity_field_storage_info.
id() === ‘node’ && $bundle === ‘my_bundle’) {
// It is not a basefield so we need a custom field storage definition see
// https://www.drupal.org/project/drupal/issues/2346347#comment-12206126
$fields[‘my_computed_property’] = FieldStorageDefinition::create(‘string’)
->setLabel(t(‘My computed property’))
->setDescription(t(‘This is my computed property.’))
->setComputed(TRUE)
->setClass(MyComputedItemList::class)
->setReadOnly(FALSE)
->setInternal(FALSE)
->setDisplayOptions(‘view’, [
‘label’ => ‘hidden’,
‘region’ => ‘hidden’,
‘weight’ => -5,
])
->setDisplayOptions(‘form’, [
‘label’ => ‘hidden’,
‘region’ => ‘hidden’,
‘weight’ => -5,
])
->setTargetEntityTypeId($entity_type->id())
->setTargetBundle($bundle)
->setName(‘my_computed_property’)
->setDisplayConfigurable(‘form’, FALSE)
->setDisplayConfigurable(‘view’, FALSE);
}
return $fields;
}
Then we need the MyComputedItemList class to perform some magic. This class will allow us to set the computed field value.
getEntity();
if ($entity->getEntityTypeId() !== ‘node’ || $entity->bundle() !== ‘my_bundle’ || $entity->my_some_other_field->isEmpty()) {
return;
}
$some_string = some_magic($entity->my_some_other_field);
$this->list[0] = $this->createItem(0, $some_string);
}
The field we add is not a base field so we can’t use Drupal maintenance support plansCoreFieldBaseFieldDefinition. There is an open core issue to address that https://www.drupal.org/project/drupal/issues/2346347 but in tests there is a workaround using a copy of Drupal maintenance support plansentity_testFieldStorageDefinition:
<?php
// my_module/src/FieldStorageDefinition.php
namespace Drupal maintenance support plansmy_module;
use Drupal maintenance support plansCoreFieldBaseFieldDefinition;
/**
* A custom field storage definition class.
*
* For convenience we extend from BaseFieldDefinition although this should not
* implement FieldDefinitionInterface.
*
* @todo Provide and make use of a proper FieldStorageDefinition class instead:
* https://www.drupal.org/node/2280639.
*/
class FieldStorageDefinition extends BaseFieldDefinition {
/**
* {@inheritdoc}
*/
public function isBaseField() {
return FALSE;
}
}
Last but not least we need to announce our property definition to the entity system so that it can keep track of it. As it is an existing bundle we can write an update hook. Otherwise, we’d need to implement hook_entity_bundle_create.
setLabel(t(‘My computed property’))
->setDescription(t(‘This is my computed property.’))
->setComputed(TRUE)
->setClass(MyComputedItemList::class)
->setReadOnly(FALSE)
->setInternal(FALSE)
->setDisplayOptions(‘view’, [
‘label’ => ‘hidden’,
‘region’ => ‘hidden’,
‘weight’ => -5,
])
->setDisplayOptions(‘form’, [
‘label’ => ‘hidden’,
‘region’ => ‘hidden’,
‘weight’ => -5,
])
->setTargetEntityTypeId(‘node’)
->setTargetBundle(‘my_bundle’)
->setName(‘my_computed_property’)
->setDisplayConfigurable(‘form’, FALSE)
->setDisplayConfigurable(‘view’, FALSE);
// Notify the storage about the new field.
Drupal maintenance support plans::service(‘field_definition.listener’)->onFieldDefinitionCreate($fields[‘my_computed_property’]);
}
The beauty of this solution is that I don’t have to write a custom serializer to normalize the output. Drupal maintenance support plans Typed Data API is doing all the heavy lifting.
Related Drupal maintenance support plans core issues:
Include processed text in normalizations: “text” field type’s “processed” computed property should be non-internal and carry cacheability metadata
Finalize API for creating, overriding, and altering code-defined bundle fields
Decouple field definitions from typed data definitions
Add a FieldStorageDefinition class
Error when saving a denormalized entity with text fields with “processed” property
Tagged
jsonapi, REST, XML, JSON, hal_json, Normalizers
Source: New feed
