Understanding Form Storage Adapters¶
Available: Liferay DXP 7.3 and Liferay DXP 7.2 versions that include the fix for LPS-97208 (planned for Liferay DXP 7.2 SP3).
When a user adds a form record, the forms API routes the processing of the request through a storage adapter API. The same is true for the other CRUD operations performed on form entries (read, update, and delete). The default implementation of the storage service is called
DefaultDDMStorageAdapter, and as its name implies, it implements the
DDMStorageAdapter interface to store form entry data in JSON format.
The Dynamic Data Mapping (DDM) back-end can adapt to other storage formats for form records. This makes it easy to serialize form data as XML or YAML (or whatever format you like) instead of the default JSON. You can then choose to store form data anywhere, including the Liferay database.
A newly added storage adapter can only be used with new Forms. All existing Forms continue to use the adapter selected (JSON by default) at the time of their creation, and a different storage adapter cannot be selected.
Saving Form Records¶
The default JSON implementation responds differently depending on the value of a boolean stored in the save request,
isInsert. If true, logic for adding a new form record is invoked, and if false, an update happens instead. This logic is contained in the methods
update. Make sure your implementation of the
DDMStorageAdapter accounts for this paradigm as well.
Serializing and Deserializing Form Records¶
The default format for serializing and deserializing form records is JSON. The example project demonstrates the use of this default format. Storing
DDMContent in a different format requires implementing additional interfaces.
Serialization: When you’re saving
DDMcontent, you must transform the
DDMFormValues object it into the target storage format.
Deserialization: When reading
DDMContent (in the
get method of the storage adapter), it must be transformed from the storage format back into a
DDMFormValues object that the
Builder constructor requires.
DDMFormValuesSerializer interface to implement for this serialization logic and a
DDMFormValuesDeserializer interface to implement for the deserialization logic. Liferay’s default implementations, which support transforming the
DDMFormValues object to JSON and vice versa, can be found here and here, respectively.
For a complete example, see Writing a Form Storage Adapter.