Adding custom logic in Odata Create Entity call in java code

Question

In the project am using olingo 2.0.12 jar in the java code.

During the create Entity service call ,

1. Is there a way to check for which entity data insert requested and,
2. Alter column values / append new column values before data persisted?

Is there a way to add above?

Code snippet given below,

public class A extends ODataJPADefaultProcessor{
          @Override
public ODataResponse createEntity(final PostUriInfo uriParserResultView, final InputStream content,
        final String requestContentType, final String contentType) throws ODataJPAModelException,
        ODataJPARuntimeException, ODataNotFoundException, EdmException, EntityProviderException {
        
        // Need to check the entity name and need to alter/add column values
        }
                  }

Answer 1

Yes one of the possible ways would be to create your own CustomODataJPAProcessor which extends ODataJPADefaultProcessor.

You will have to register this in JPAServiceFactory by overriding the method

    @Override
    public ODataSingleProcessor createCustomODataProcessor(ODataJPAContext oDataJPAContext) {
        return new CustomODataJPAProcessor(this.oDataJPAContext);
    }

Now Olingo will use CustomODataJPAProcessor which can implement the following code to check the entities and transform them if needed

Sample code of CustomODataJPAProcessor

public class CustomODataJPAProcessor extends ODataJPADefaultProcessor {

    Logger LOG = LoggerFactory.getLogger(this.getClass());

    public CustomODataJPAProcessor(ODataJPAContext oDataJPAContext) {
        super(oDataJPAContext);

    }

    @Override
    public ODataResponse createEntity(final PostUriInfo uriParserResultView, final InputStream content,
            final String requestContentType, final String contentType) throws ODataException {
        ODataResponse oDataResponse = null;
        oDataJPAContext.setODataContext(getContext());
        InputStream forwardedInputStream = content;
        try {
            if (uriParserResultView.getTargetEntitySet().getName().equals("Students")) {
                LOG.info("Students Entity Set Executed");

                if (requestContentType.equalsIgnoreCase(ContentType.APPLICATION_JSON.toContentTypeString())) {
                    @SuppressWarnings("deprecation")
                    JsonElement elem = new JsonParser().parse(new InputStreamReader(content));
                    Gson gson = new GsonBuilder().setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE).create();
                    Student s = gson.fromJson(elem, Student.class);

                    // Change some values
                    s.setStudentID("Test" + s.getStudentID());
                    forwardedInputStream = new ByteArrayInputStream(gson.toJson(s).getBytes());

                }
            }
            Object createdJpaEntity = jpaProcessor.process(uriParserResultView, forwardedInputStream,
                    requestContentType);
            oDataResponse = responseBuilder.build(uriParserResultView, createdJpaEntity, contentType);
        } catch (JsonIOException | JsonSyntaxException e) {
            throw new RuntimeException(e);
        } finally {
            close();
        }

        return oDataResponse;
    }
}

In Summery

1. Register your custom org.apache.olingo.odata2.service.factory Code Link
2. Create your own CustomODataJPAProcessor Code Link
3. Override createCustomODataProcessor in JPAServiceFactory to use the custom processor Code Link