Writing a Form Storage Adapter

Liferay DXP 7.3 and Liferay DXP 7.2 versions that include the fix for LPS-97208 (planned for Liferay DXP 7.2 SP3)

By default, forms are stored as JSON in Liferay DXP’s database. This example shows you how to implement a new storage adapter to inject custom logic into a form record persistence event.

Use a DDM Storage Adapter to add a Storage Type to the Forms application.

The default storage adapter saves form records in the Liferay DXP database as JSON content. Next, add logic to store each Form Record on the file system.

Examine a Running DDM Storage Adapter

To see how storage adapters work, deploy an example and then add some form data using the example adapter.

Deploy the Example

Start a new Liferay instance by running

docker run -it -m 8g -p 8080:8080 liferay/portal:7.4.3.132-ga132

Sign in to Liferay at http://localhost:8080. Use the email address test@liferay.com and the password test. When prompted, change the password to learn.

Then, follow these steps:

Download and unzip the DDM Storage Adapter project.

curl https://resources.learn.liferay.com/examples/liferay-r2f1.zip -O

unzip liferay-r2f1.zip

From the module root, build and deploy.
```
./gradlew deploy -Ddeploy.docker.container.id=$(docker ps -lq)
```
Tip

This command is the same as copying the deployed jars to /opt/liferay/osgi/modules on the Docker container.
Confirm the deployment in the Liferay Docker container console.

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STARTED com.acme.r2f1.impl_1.0.0 [1009]

Use the Deployed Storage Adapter Powered by Liferay

Open your browser to http://localhost:8080.
Go to the Forms application in Site Menu → Content & Data → Forms.
Click Add () to open the Form Builder.
In the Form Builder view, click Options () and open the Settings window.
Under Select a Storage Type, choose the R2F1 Dynamic Data Mapping Storage Adapter type and click Done.
Add a Text Field to the form, publish the form, and submit it a few times.
To verify the form data were persisted, go to the Form’s Records:

From Site Menu → Content → Forms, click the Form’s Actions button (), then View Entries.
Additionally, logging is provided in each CRUD method to demonstrate that the sample’s methods are being invoked.

private void _deleteFile(long fileId) {
   File file = new File(_PATHNAME + "/" + fileId);

   file.delete();

   if (_log.isWarnEnabled()) {
   _log.warn("Deleted file with the ID " + fileId);
   }
}

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Find the overridden delete method. Immediately before the return statement, add

 long fileId = ddmStorageAdapterDeleteRequest.getPrimaryKey();

 _deleteFile(fileId);

Now the code first deletes the file from the file system before it deletes the copy in the database.

Implement File Retrieval

Follow the same procedure for the get method: create a private utility method and then call it.

Add the _getFile utility method:

	private void _getFile(long fileId) throws IOException {
		try {
			if (_log.isWarnEnabled()) {
				_log.warn(
					"Reading the file with the ID " + fileId + ": " +
						FileUtil.read(_PATHNAME + "/" + fileId));
			}
		}
		catch (IOException e) {
			throw new IOException(e);
		}
	}

Import com.liferay.portal.kernel.util.FileUtil and java.io.IOException.

In the overridden get method (inside the try block), insert the following immediately before the return statement, setting the storageId (retrieved by ddmStorageAdapterGetRequest.getPrimaryKey()) as the fileId and calling the _getFile utility method which prints the retrieved content to the Liferay log.
```
long fileId = ddmStorageAdapterGetRequest.getPrimaryKey();

_getFile(fileId);
```

There are two types of save requests: 1) a new record is added or 2) an existing record is updated. At each save, the update method overwrites the existing file, using the current ddmFormValues content.

Create a _saveFile utility method:

private void _saveFile(long fileId, DDMFormValues formValues)
   throws IOException {

   try {
      String serializedDDMFormValues = _serialize(formValues);

      File abstractFile = new File(String.valueOf(fileId));

      FileUtil.write(
         _PATHNAME, abstractFile.getName(), serializedDDMFormValues);

      if (_log.isWarnEnabled()) {
         _log.warn("Saved a file with the ID" + fileId);
      }
   }
   catch (IOException e) {
      throw new IOException(e);
   }
}

Import com.liferay.dynamic.data.mapping.storage.DDMFormValues and java.io.File.

Create a _serialize utility method to convert the DDMFormValues object to JSON:

	private String _serialize(DDMFormValues ddmFormValues) {
		DDMFormValuesSerializer ddmFormValuesSerializer =
			_ddmFormValuesSerializerTracker.getDDMFormValuesSerializer("json");

		DDMFormValuesSerializerSerializeRequest.Builder builder =
			DDMFormValuesSerializerSerializeRequest.Builder.newBuilder(
				ddmFormValues);

		DDMFormValuesSerializerSerializeResponse
			ddmFormValuesSerializerSerializeResponse =
				ddmFormValuesSerializer.serialize(builder.build());

		return ddmFormValuesSerializerSerializeResponse.getContent();
	}

Import com.liferay.dynamic.data.mapping.io.DDMFormValuesSerializer, com.liferay.dynamic.data.mapping.io.DDMFormValuesSerializerSerializeRequest, and com.liferay.dynamic.data.mapping.io.DDMFormValuesSerializerSerializeResponse.

Add this logic and the call to _saveFile to the save method by replacing the existing return statement:

DDMStorageAdapterSaveResponse defaultStorageAdapterSaveResponse =
   _defaultStorageAdapter.save(ddmStorageAdapterSaveRequest);

long fileId = defaultStorageAdapterSaveResponse.getPrimaryKey();

_saveFile(fileId, ddmStorageAdapterSaveRequest.getDDMFormValues());

return defaultStorageAdapterSaveResponse;

The _defaultStorageAdapter.save call is made first, so that a Primary Key is created for a new form entry. This Primary Key is retrieved from the Response object to create the fielId.

Deploy and Test the Storage Adapter

Use the same deploy command as earlier to deploy the Storage Adapter. From the module root run

./gradlew deploy -Ddeploy.docker.container.id=$(docker ps -lq)

Now verify that it’s working:

Go to the Forms application in Site Menu → Content → Forms.
Click Add to open the Form Builder.
In the Form Builder view, click Options () and open the Settings window.
From the select list field called Select a Storage Type, choose the R2F1 Dynamic Data Mapping Storage Adapter type and click Done.
Add a Text Field to the form, publish the form, and submit it a few times.

To verify the form records were written to the container’s file system, check the log. The messages should look like this:

WARN  [http-nio-8080-exec-5][R2F1DDMStorageAdapter:82] Acme storage adapter's save method was invoked
WARN  [http-nio-8080-exec-5][R2F1DDMStorageAdapter:134] Saved a file with the ID42088
WARN  [http-nio-8080-exec-5][R2F1DDMStorageAdapter:61] Acme storage adapter's get method was invoked
WARN  [http-nio-8080-exec-5][R2F1DDMStorageAdapter:112] Reading the file with the ID 42088: {"availableLanguageIds":["en_US"],"defaultLanguageId":"en_US","fieldValues":[{"instanceId":"EJ5UglA1","name":"Field51665758","value":{"en_US":"Stretched limousine"}}]}