Java Code Examples for org.apache.olingo.commons.api.data.EntityCollection#getEntities()

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet,
    List<UriParameter> keyParams) throws ODataApplicationException {

  List<Entity> entityList = entitySet.getEntities();

  // loop over all entities in order to find that one that matches
  // all keys in request e.g. contacts(ContactID=1, CompanyID=1)
  for (Entity entity : entityList) {
    boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
    if (foundEntity) {
      return entity;
    }
  }

  return null;
}
 

@SuppressWarnings("unchecked")
private EntityCollection getEvents(int tripId, EntityCollection result) {
  Map<String, Object> map = this.tripLinks.get(tripId);
  if (map == null) {
    return null;
  }

  ArrayList<Integer> events = (ArrayList<Integer>) map.get("Events");
  EntityCollection set = getEntitySet("Event");
  int i = result.getEntities().size();
  if (events != null) {
    for (int event : events) {
      for (Entity e : set.getEntities()) {
        if (e.getProperty("PlanItemId").getValue().equals(event)) {
          result.getEntities().add(e);
          i++;
          break;
        }
      }
    }
  }
  result.setCount(i);
  return result;
}
 

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet,
    List<UriParameter> keyParams) {

  List<Entity> entityList = entitySet.getEntities();

  // loop over all entities in order to find that one that matches
  // all keys in request e.g. contacts(ContactID=1, CompanyID=1)
  for (Entity entity : entityList) {
    boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
    if (foundEntity) {
      return entity;
    }
  }

  return null;
}
 

@SuppressWarnings("unchecked")
private EntityCollection getFlights(int tripId, EntityCollection result) {
  Map<String, Object> map = this.tripLinks.get(tripId);
  if (map == null) {
    return null;
  }

  ArrayList<Integer> flights = (ArrayList<Integer>) map.get("Flights");
  EntityCollection set = getEntitySet("Flight");
  int i = result.getEntities().size();
  if (flights != null) {
    for (int flight : flights) {
      for (Entity e : set.getEntities()) {
        if (e.getProperty("PlanItemId").getValue().equals(flight)) {
          result.getEntities().add(e);
          i++;
          break;
        }
      }
    }
  }
  result.setCount(i);
  return result;
}
 

public EntityCollection getEntitySet(String name, int skip, int pageSize) {
  EntityCollection set = this.entitySetMap.get(name);
  if (set == null) {
    return null;
  }

  EntityCollection modifiedES = new EntityCollection();
  int i = 0;
  for (Entity e : set.getEntities()) {
    if (skip >= 0 && i >= skip && modifiedES.getEntities().size() < pageSize) {
      modifiedES.getEntities().add(e);
    }
    i++;
  }
  modifiedES.setCount(i);
  set.setCount(i);

  if (skip == -1 && pageSize == -1) {
    return set;
  }
  return modifiedES;
}
 

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet,
                                List<UriParameter> keyParams) throws ODataApplicationException {

  List<Entity> entityList = entitySet.getEntities();

  // loop over all entities in order to find that one that matches all keys in request
  // e.g. contacts(ContactID=1, CompanyID=1)
  for (Entity entity: entityList) {
    boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
    if (foundEntity) {
      return entity;
    }
  }

  return null;
}
 

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet,
                                List<UriParameter> keyParams) throws ODataApplicationException {

  List<Entity> entityList = entitySet.getEntities();

  // loop over all entities in order to find that one that matches all keys in request
  // e.g. contacts(ContactID=1, CompanyID=1)
  for (Entity entity: entityList) {
    boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
    if (foundEntity) {
      return entity;
    }
  }

  return null;
}
 

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet,
    List<UriParameter> keyParams) throws ODataApplicationException {

  List<Entity> entityList = entitySet.getEntities();

  // loop over all entities in order to find that one that matches all keys in request
  // e.g. contacts(ContactID=1, CompanyID=1)
  for (Entity entity: entityList) {
    boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
    if (foundEntity) {
      return entity;
    }
  }

  return null;
}
 

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet,
    List<UriParameter> keyParams) throws ODataApplicationException {

  List<Entity> entityList = entitySet.getEntities();

  // loop over all entities in order to find that one that matches
  // all keys in request e.g. contacts(ContactID=1, CompanyID=1)
  for (Entity entity : entityList) {
    boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
    if (foundEntity) {
      return entity;
    }
  }

  return null;
}
 

public Entity create(final EdmEntitySet edmEntitySet) throws DataProviderException {
  final EdmEntityType edmEntityType = edmEntitySet.getEntityType();
  EntityCollection entitySet = readAll(edmEntitySet);
  final List<Entity> entities = entitySet.getEntities();
  final Map<String, Object> newKey = findFreeComposedKey(entities, edmEntityType);
  Entity newEntity = new Entity();
  newEntity.setType(edmEntityType.getFullQualifiedName().getFullQualifiedNameAsString());
  for (final String keyName : edmEntityType.getKeyPredicateNames()) {
    newEntity.addProperty(DataCreator.createPrimitive(keyName, newKey.get(keyName)));
  }

  createProperties(edmEntityType, newEntity.getProperties());
  try {
    newEntity.setId(URI.create(odata.createUriHelper().buildCanonicalURL(edmEntitySet, newEntity)));
  } catch (final SerializerException e) {
    throw new DataProviderException("Unable to set entity ID!", HttpStatusCode.INTERNAL_SERVER_ERROR, e);
  }
  entities.add(newEntity);

  return newEntity;
}
 

/**
 * Helper method for providing some sample data
 * @param edmEntitySet for which the data is requested
 * @return data of requested entity set
 */
private EntityCollection getData(EdmEntitySet edmEntitySet){

  EntityCollection productsCollection = new EntityCollection();
  // check for which EdmEntitySet the data is requested
  if(DemoEdmProvider.ES_PRODUCTS_NAME.equals(edmEntitySet.getName())) {
    List<Entity> productList = productsCollection.getEntities();

    // add some sample product entities
    final Entity e1 = new Entity()
        .addProperty(new Property(null, "ID", ValueType.PRIMITIVE, 1))
        .addProperty(new Property(null, "Name", ValueType.PRIMITIVE, "Notebook Basic 15"))
        .addProperty(new Property(null, "Description", ValueType.PRIMITIVE,
            "Notebook Basic, 1.7GHz - 15 XGA - 1024MB DDR2 SDRAM - 40GB"));
    e1.setId(createId("Products", 1));
    productList.add(e1);

    final Entity e2 = new Entity()
        .addProperty(new Property(null, "ID", ValueType.PRIMITIVE, 2))
        .addProperty(new Property(null, "Name", ValueType.PRIMITIVE, "1UMTS PDA"))
        .addProperty(new Property(null, "Description", ValueType.PRIMITIVE,
            "Ultrafast 3G UMTS/HSDPA Pocket PC, supports GSM network"));
    e2.setId(createId("Products", 1));
    productList.add(e2);

    final Entity e3 = new Entity()
        .addProperty(new Property(null, "ID", ValueType.PRIMITIVE, 3))
        .addProperty(new Property(null, "Name", ValueType.PRIMITIVE, "Ergo Screen"))
        .addProperty(new Property(null, "Description", ValueType.PRIMITIVE,
            "19 Optimum Resolution 1024 x 768 @ 85Hz, resolution 1280 x 960"));
    e3.setId(createId("Products", 1));
    productList.add(e3);
  }

  return productsCollection;
}
 

private List<Entity> createInlineEntities(final String rawBaseUri, final EdmEntitySet targetEntitySet,
    final EntityCollection changedEntitySet) throws DataProviderException {
  List<Entity> entities = new ArrayList<Entity>();

  for (final Entity newEntity : changedEntitySet.getEntities()) {
    entities.add(createInlineEntity(rawBaseUri, targetEntitySet, newEntity));
  }

  return entities;
}
 

/**
 * Helper method for providing some sample data
 * @param edmEntitySet for which the data is requested
 * @return data of requested entity set
 */
private EntityCollection getData(EdmEntitySet edmEntitySet) {

    EntityCollection productsCollection = new EntityCollection();
    // check for which EdmEntitySet the data is requested
    if (DemoEdmProvider.ES_PRODUCTS_NAME.equals(edmEntitySet.getName())) {
        List<Entity> productList = productsCollection.getEntities();

        // add some sample product entities
        final Entity e1 = new Entity()
                .addProperty(new Property(null, "ID", ValueType.PRIMITIVE, 1))
                .addProperty(new Property(null, "Name", ValueType.PRIMITIVE, "Notebook Basic 15"))
                .addProperty(new Property(null, "Description", ValueType.PRIMITIVE,
                        "Notebook Basic, 1.7GHz - 15 XGA - 1024MB DDR2 SDRAM - 40GB"));
        e1.setId(createId("Products", 1));
        productList.add(e1);

        final Entity e2 = new Entity()
                .addProperty(new Property(null, "ID", ValueType.PRIMITIVE, 2))
                .addProperty(new Property(null, "Name", ValueType.PRIMITIVE, "1UMTS PDA"))
                .addProperty(new Property(null, "Description", ValueType.PRIMITIVE,
                        "Ultrafast 3G UMTS/HSDPA Pocket PC, supports GSM network"));
        e2.setId(createId("Products", 1));
        productList.add(e2);

        final Entity e3 = new Entity()
                .addProperty(new Property(null, "ID", ValueType.PRIMITIVE, 3))
                .addProperty(new Property(null, "Name", ValueType.PRIMITIVE, "Ergo Screen"))
                .addProperty(new Property(null, "Description", ValueType.PRIMITIVE,
                        "19 Optimum Resolution 1024 x 768 @ 85Hz, resolution 1280 x 960"));
        e3.setId(createId("Products", 1));
        productList.add(e3);
    }

    return productsCollection;
}
 

public static Entity findEntity(EdmEntityType edmEntityType, EntityCollection entitySet, List<UriParameter> keyParams) throws ODataApplicationException {
	
	List<Entity> entityList = entitySet.getEntities();
	
	// loop over all entities in order to find that one that matches all keys in request e.g. contacts(ContactID=1, CompanyID=1) 
	for(Entity entity : entityList){
		boolean foundEntity = entityMatchesAllKeys(edmEntityType, entity, keyParams);
		if(foundEntity) {
			return entity;
		}
	}
	
	return null;
}
 

public Entity readDataFromEntity(final EdmEntityType edmEntityType,
    final List<UriParameter> keys) throws DataProviderException {
  EntityCollection coll = data.get(edmEntityType.getName());
  List<Entity> entities = coll.getEntities();
  try {
    for (final Entity entity : entities) {
      boolean found = true;
      for (final UriParameter key : keys) {
        EdmKeyPropertyRef refType = edmEntityType.getKeyPropertyRef(key.getName());
        Object value =  findPropertyRefValue(entity, refType);
        
        final EdmProperty property = refType.getProperty();
        final EdmPrimitiveType type = (EdmPrimitiveType) property.getType();
        
        if (key.getExpression() != null && !(key.getExpression() instanceof Literal)) {
          throw new DataProviderException("Expression in key value is not supported yet!",
              HttpStatusCode.NOT_IMPLEMENTED);
        }
        final String text = key.getAlias() == null ? key.getText() : ((Literal) key.getExpression()).getText();
        Object keyValue = null;
        if (Calendar.class.isAssignableFrom(value.getClass())) {
          keyValue = type.valueOfString(type.fromUriLiteral(text),
              property.isNullable(), property.getMaxLength(), property.getPrecision(), property.getScale(),
              property.isUnicode(), Calendar.class);
        } else {
          keyValue = type.valueOfString(type.fromUriLiteral(text),
              property.isNullable(), property.getMaxLength(), property.getPrecision(), property.getScale(),
              property.isUnicode(), value.getClass());
        }
        if (!value.equals(keyValue)) {
          found = false;
          break;
        }
      }
      if (found) {
        return entity;
      }
    }
    return null;
  } catch (final EdmPrimitiveTypeException e) {
    throw new DataProviderException("Wrong key!", HttpStatusCode.BAD_REQUEST, e);
  }
}
 

public void readEntityCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo, 
    ContentType responseFormat) throws ODataApplicationException, SerializerException {

	// 1st retrieve the requested EntitySet from the uriInfo (representation of the parsed URI)
	List<UriResource> resourcePaths = uriInfo.getUriResourceParts();
	// in our example, the first segment is the EntitySet
	UriResourceEntitySet uriResourceEntitySet = (UriResourceEntitySet) resourcePaths.get(0); 
	EdmEntitySet edmEntitySet = uriResourceEntitySet.getEntitySet();

	// 2nd: fetch the data from backend for this requested EntitySetName and deliver as EntitySet
	EntityCollection entityCollection = storage.readEntitySetData(edmEntitySet);
	List<Entity> entityList = entityCollection.getEntities();
	
	// 3rd apply $orderby
	OrderByOption orderByOption = uriInfo.getOrderByOption();
	if (orderByOption != null) {
		List<OrderByItem> orderItemList = orderByOption.getOrders();
		final OrderByItem orderByItem = orderItemList.get(0); // in our example we support only one
		Expression expression = orderByItem.getExpression();
		if(expression instanceof Member){
			UriInfoResource resourcePath = ((Member)expression).getResourcePath();
			UriResource uriResource = resourcePath.getUriResourceParts().get(0);
			if (uriResource instanceof UriResourcePrimitiveProperty) {
				EdmProperty edmProperty = ((UriResourcePrimitiveProperty)uriResource).getProperty();
				final String sortPropertyName = edmProperty.getName();

				// do the sorting for the list of entities  
				Collections.sort(entityList, new Comparator<Entity>() {

					// we delegate the sorting to the native sorter of Integer and String
					public int compare(Entity entity1, Entity entity2) {
						int compareResult = 0;

						if(sortPropertyName.equals("ID")){
							Integer integer1 = (Integer) entity1.getProperty(sortPropertyName).getValue();
							Integer integer2 = (Integer) entity2.getProperty(sortPropertyName).getValue();
							
							compareResult = integer1.compareTo(integer2);
						}else{
							String propertyValue1 = (String) entity1.getProperty(sortPropertyName).getValue();
							String propertyValue2 = (String) entity2.getProperty(sortPropertyName).getValue();
							
							compareResult = propertyValue1.compareTo(propertyValue2);
						}

						// if 'desc' is specified in the URI, change the order of the list 
						if(orderByItem.isDescending()){
							return - compareResult; // just convert the result to negative value to change the order
						}
						
						return compareResult;
					}
				});
			}
		}
	}
	
	
	// 4th: create a serializer based on the requested format (json)
	ODataSerializer serializer = odata.createSerializer(responseFormat);

	// and serialize the content: transform from the EntitySet object to InputStream
	EdmEntityType edmEntityType = edmEntitySet.getEntityType();
	ContextURL contextUrl = ContextURL.with().entitySet(edmEntitySet).build();

	final String id = request.getRawBaseUri() + "/" + edmEntitySet.getName();
	EntityCollectionSerializerOptions opts =
			EntityCollectionSerializerOptions.with().id(id).contextURL(contextUrl).build();
   SerializerResult serializerResult = serializer.entityCollection(serviceMetadata, edmEntityType, 
                                                                   entityCollection, opts);
	InputStream serializedContent = serializerResult.getContent();

	// 5th: configure the response object: set the body, headers and status code
	response.setContent(serializedContent);
	response.setStatusCode(HttpStatusCode.OK.getStatusCode());
	response.setHeader(HttpHeader.CONTENT_TYPE, responseFormat.toContentTypeString());
}
 

protected void doContainerSerialize(final ResWrap<EntityCollection> container, final JsonGenerator jgen)
    throws IOException, EdmPrimitiveTypeException {

  final EntityCollection entitySet = container.getPayload();

  jgen.writeStartObject();

  if (serverMode && !isODataMetadataNone) {
    if (container.getContextURL() != null) {
      jgen.writeStringField(Constants.JSON_CONTEXT, container.getContextURL().toASCIIString());
    }

    if (container.getMetadataETag() != null) {
      jgen.writeStringField(Constants.JSON_METADATA_ETAG, container.getMetadataETag());
    }
  }

  if (entitySet.getId() != null && isODataMetadataFull) {
    jgen.writeStringField(Constants.JSON_ID, entitySet.getId().toASCIIString());
  }
  final Integer count = entitySet.getCount() == null ? entitySet.getEntities().size() : entitySet.getCount();
  if (isIEEE754Compatible) {
    jgen.writeStringField(Constants.JSON_COUNT, Integer.toString(count));
  } else {
    jgen.writeNumberField(Constants.JSON_COUNT, count);
  }
  if (serverMode) {
    if (entitySet.getNext() != null) {
      jgen.writeStringField(Constants.JSON_NEXT_LINK,
          entitySet.getNext().toASCIIString());
    }
    if (entitySet.getDeltaLink() != null && !isODataMetadataNone) {
      jgen.writeStringField(Constants.JSON_DELTA_LINK,
          entitySet.getDeltaLink().toASCIIString());
    }
  }

  for (Annotation annotation : entitySet.getAnnotations()) {
    valuable(jgen, annotation, "@" + annotation.getTerm());
  }

  jgen.writeArrayFieldStart(Constants.VALUE);
  final JsonEntitySerializer entitySerializer = new JsonEntitySerializer(serverMode, contentType);
  for (Entity entity : entitySet.getEntities()) {
    entitySerializer.doSerialize(entity, jgen);
  }
  jgen.writeEndArray();

  jgen.writeEndObject();
}
 

public Entity read(final EdmEntityType edmEntityType, final EntityCollection entitySet,
    final List<UriParameter> keys) throws DataProviderException {
  try {
    for (final Entity entity : entitySet.getEntities()) {
      boolean found = true;
      for (final UriParameter key : keys) {
        EdmKeyPropertyRef refType = edmEntityType.getKeyPropertyRef(key.getName());
        Object value =  findPropertyRefValue(entity, refType);
        
        final EdmProperty property = refType.getProperty();
        final EdmPrimitiveType type = (EdmPrimitiveType) property.getType();
        
        if (key.getExpression() != null && !(key.getExpression() instanceof Literal)) {
          throw new DataProviderException("Expression in key value is not supported yet!",
              HttpStatusCode.NOT_IMPLEMENTED);
        }
        Object keyValue = null;
        final String text = key.getAlias() == null ? key.getText() : ((Literal) key.getExpression()).getText();
        if (Calendar.class.isAssignableFrom(value.getClass())) {
          keyValue = type.valueOfString(type.fromUriLiteral(text),
              property.isNullable(), property.getMaxLength(), property.getPrecision(), property.getScale(),
              property.isUnicode(), Calendar.class);
        } else {
          keyValue = type.valueOfString(type.fromUriLiteral(text),
              property.isNullable(), property.getMaxLength(), property.getPrecision(), property.getScale(),
              property.isUnicode(), value.getClass());
        }
        if (!value.equals(keyValue)) {
          found = false;
          break;
        }
      }
      if (found) {
        return entity;
      }
    }
    return null;
  } catch (final EdmPrimitiveTypeException e) {
    throw new DataProviderException("Wrong key!", HttpStatusCode.BAD_REQUEST, e);
  }
}
 

public void readEntityCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo, 
    ContentType responseFormat) throws ODataApplicationException, SerializerException {

	// 1st: retrieve the requested EntitySet from the uriInfo (representation of the parsed URI)
	List<UriResource> resourcePaths = uriInfo.getUriResourceParts();
	// in our example, the first segment is the EntitySet
	UriResourceEntitySet uriResourceEntitySet = (UriResourceEntitySet) resourcePaths.get(0); 
	EdmEntitySet edmEntitySet = uriResourceEntitySet.getEntitySet();

	// 2nd: fetch the data from backend for this requested EntitySetName and deliver as EntitySet
	EntityCollection entityCollection = storage.readEntitySetData(edmEntitySet);
	
	// 3rd: Check if filter system query option is provided and apply the expression if necessary
	FilterOption filterOption = uriInfo.getFilterOption();
	if(filterOption != null) {
		// Apply $filter system query option
		try {
		      List<Entity> entityList = entityCollection.getEntities();
		      Iterator<Entity> entityIterator = entityList.iterator();
		      
		      // Evaluate the expression for each entity
		      // If the expression is evaluated to "true", keep the entity otherwise remove it from the entityList
		      while (entityIterator.hasNext()) {
		    	  // To evaluate the the expression, create an instance of the Filter Expression Visitor and pass
		    	  // the current entity to the constructor
		    	  Entity currentEntity = entityIterator.next();
		    	  Expression filterExpression = filterOption.getExpression();
		    	  FilterExpressionVisitor expressionVisitor = new FilterExpressionVisitor(currentEntity);
		    	  
		    	  // Start evaluating the expression
		    	  Object visitorResult = filterExpression.accept(expressionVisitor);
		    	  
		    	  // The result of the filter expression must be of type Edm.Boolean
		    	  if(visitorResult instanceof Boolean) {
		    		  if(!Boolean.TRUE.equals(visitorResult)) {
		    		    // The expression evaluated to false (or null), so we have to remove the currentEntity from entityList
		    		    entityIterator.remove();
		    		  }
		    	  } else {
		    		  throw new ODataApplicationException("A filter expression must evaulate to type Edm.Boolean", 
		    		      HttpStatusCode.BAD_REQUEST.getStatusCode(), Locale.ENGLISH);
		    	  }
		      }

		    } catch (ExpressionVisitException e) {
		      throw new ODataApplicationException("Exception in filter evaluation",
		          HttpStatusCode.INTERNAL_SERVER_ERROR.getStatusCode(), Locale.ENGLISH);
		    }
	}
	
	// 4th: create a serializer based on the requested format (json)
	ODataSerializer serializer = odata.createSerializer(responseFormat);

	// and serialize the content: transform from the EntitySet object to InputStream
	EdmEntityType edmEntityType = edmEntitySet.getEntityType();
	ContextURL contextUrl = ContextURL.with().entitySet(edmEntitySet).build();

	final String id = request.getRawBaseUri() + "/" + edmEntitySet.getName();
	EntityCollectionSerializerOptions opts = EntityCollectionSerializerOptions.with()
			.contextURL(contextUrl).id(id).build();
	SerializerResult serializerResult = serializer.entityCollection(serviceMetadata, edmEntityType, entityCollection,
			opts);

	InputStream serializedContent = serializerResult.getContent();

	// 5th: configure the response object: set the body, headers and status code
	response.setContent(serializedContent);
	response.setStatusCode(HttpStatusCode.OK.getStatusCode());
	response.setHeader(HttpHeader.CONTENT_TYPE, responseFormat.toContentTypeString());
}
 

@Override
public void readEntityCollection(ODataRequest request, ODataResponse response, UriInfo uriInfo, ContentType responseFormat)
    throws ODataApplicationException, ODataLibraryException {
    // 1st we have retrieve the requested EntitySet from the uriInfo object (representation of the parsed service URI)
    List<UriResource> resourcePaths = uriInfo.getUriResourceParts();
    UriResourceEntitySet uriResourceEntitySet = (UriResourceEntitySet)resourcePaths.get(0); // in our example, the first segment is the EntitySet
    EdmEntitySet edmEntitySet = uriResourceEntitySet.getEntitySet();

    // 2nd: fetch the data from backend for this requested EntitySetName
    // it has to be delivered as EntitySet object
    EntityCollection entityCollection = storage.readEntitySetData(edmEntitySet);

    // 3rd: apply System Query Options
    // modify the result set according to the query options, specified by the end user
    List<Entity> entityList = entityCollection.getEntities();
    EntityCollection returnEntityCollection = new EntityCollection();

    // handle $count: always return the original number of entities, without considering $top and $skip
    CountOption countOption = uriInfo.getCountOption();
    if (countOption != null) {
        boolean isCount = countOption.getValue();
        if (isCount) {
            returnEntityCollection.setCount(entityList.size());
        }
    }

    applyQueryOptions(uriInfo, entityList, returnEntityCollection);

    // 3rd: create a serializer based on the requested format (json)
    ODataSerializer serializer = odata.createSerializer(responseFormat);

    // 4th: Now serialize the content: transform from the EntitySet object to InputStream
    EdmEntityType edmEntityType = edmEntitySet.getEntityType();
    ContextURL contextUrl = ContextURL.with().entitySet(edmEntitySet).build();

    final String id = request.getRawBaseUri() + "/" + edmEntitySet.getName();
    EntityCollectionSerializerOptions opts =
        EntityCollectionSerializerOptions
            .with().id(id)
            .count(countOption)
            .contextURL(contextUrl)
            .build();

    SerializerResult serializerResult = serializer.entityCollection(serviceMetadata,
                                                                    edmEntityType,
                                                                    returnEntityCollection,
                                                                    opts);
    InputStream serializedContent = serializerResult.getContent();

    // Finally: configure the response object: set the body, headers and status code
    response.setContent(serializedContent);
    response.setStatusCode(HttpStatusCode.OK.getStatusCode());
    response.setHeader(HttpHeader.CONTENT_TYPE, responseFormat.toContentTypeString());
}