[OLINGO-935] API for EDM-assisted serializer

Signed-off-by: Christian Amend <christian.amend@sap.com>

lib/server-api/src/main/java/org/apache/olingo/server/api/OData.java

@@ -34,6 +34,7 @@ import org.apache.olingo.server.api.deserializer.ODataDeserializer;
 import org.apache.olingo.server.api.etag.ETagHelper;
 import org.apache.olingo.server.api.etag.ServiceMetadataETagSupport;
 import org.apache.olingo.server.api.prefer.Preferences;
+import org.apache.olingo.server.api.serializer.EdmAssistedSerializer;
 import org.apache.olingo.server.api.serializer.FixedFormatSerializer;
 import org.apache.olingo.server.api.serializer.ODataSerializer;
 import org.apache.olingo.server.api.serializer.SerializerException;
@@ -175,4 +176,12 @@ public abstract class OData {
    * @return a debug-response helper
    */
   public abstract DebugResponseHelper createDebugResponseHelper(String debugFormat);
+
+  /**
+   * Creates a new serializer object capable of working without EDM information
+   * for rendering content in the specified format.
+   * @param contentType a content type supported by Olingo
+   */
+  public abstract EdmAssistedSerializer createEdmAssistedSerializer(final ContentType contentType)
+      throws SerializerException;
 }

lib/server-api/src/main/java/org/apache/olingo/server/api/serializer/EdmAssistedSerializer.java

@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.olingo.server.api.serializer;
+
+import org.apache.olingo.commons.api.data.AbstractEntityCollection;
+import org.apache.olingo.commons.api.edm.EdmEntityType;
+import org.apache.olingo.server.api.ServiceMetadata;
+
+/** EDM-assisted serializer */
+public interface EdmAssistedSerializer {
+
+  /**
+   * Writes entity-collection data into an InputStream.
+   * Information from the EDM is used in addition to information from the data and preferred,
+   * but the serializer works without any EDM information as well.
+   * Linked data is always written as expanded items (so closed reference loops have to be avoided).
+   * @param metadata             metadata for the service
+   * @param referencedEntityType the {@link EdmEntityType} or <code>null</code> if not available
+   * @param entityCollection     the data of the entity collection
+   * @param options              options for the serializer
+   */
+  SerializerResult entityCollection(ServiceMetadata metadata, EdmEntityType referencedEntityType,
+      AbstractEntityCollection entityCollection, EdmAssistedSerializerOptions options) throws SerializerException;
+}

lib/server-api/src/main/java/org/apache/olingo/server/api/serializer/EdmAssistedSerializerOptions.java

@@ -0,0 +1,58 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.olingo.server.api.serializer;
+
+import org.apache.olingo.commons.api.data.ContextURL;
+
+/** Options for the EDM-assisted serializer. */
+public class EdmAssistedSerializerOptions {
+
+  private ContextURL contextURL;
+
+  /** Gets the {@link ContextURL}. */
+  public ContextURL getContextURL() {
+    return contextURL;
+  }
+
+  /** Initializes the options builder. */
+  public static Builder with() {
+    return new Builder();
+  }
+
+  /** Builder of serializer options. */
+  public static final class Builder {
+
+    private final EdmAssistedSerializerOptions options;
+
+    private Builder() {
+      options = new EdmAssistedSerializerOptions();
+    }
+
+    /** Sets the {@link ContextURL}. */
+    public Builder contextURL(final ContextURL contextURL) {
+      options.contextURL = contextURL;
+      return this;
+    }
+
+    /** Builds the OData serializer options. */
+    public EdmAssistedSerializerOptions build() {
+      return options;
+    }
+  }
+}

lib/server-core/src/main/java/org/apache/olingo/server/core/ODataImpl.java

@@ -38,6 +38,7 @@ import org.apache.olingo.server.api.deserializer.ODataDeserializer;
 import org.apache.olingo.server.api.etag.ETagHelper;
 import org.apache.olingo.server.api.etag.ServiceMetadataETagSupport;
 import org.apache.olingo.server.api.prefer.Preferences;
+import org.apache.olingo.server.api.serializer.EdmAssistedSerializer;
 import org.apache.olingo.server.api.serializer.FixedFormatSerializer;
 import org.apache.olingo.server.api.serializer.ODataSerializer;
 import org.apache.olingo.server.api.serializer.SerializerException;
@@ -50,6 +51,7 @@ import org.apache.olingo.server.core.deserializer.xml.ODataXmlDeserializer;
 import org.apache.olingo.server.core.etag.ETagHelperImpl;
 import org.apache.olingo.server.core.prefer.PreferencesImpl;
 import org.apache.olingo.server.core.serializer.FixedFormatSerializerImpl;
+import org.apache.olingo.server.core.serializer.json.EdmAssistedJsonSerializer;
 import org.apache.olingo.server.core.serializer.json.ODataJsonSerializer;
 import org.apache.olingo.server.core.serializer.xml.ODataXmlSerializer;
 import org.apache.olingo.server.core.uri.UriHelperImpl;
@@ -86,6 +88,15 @@ public class ODataImpl extends OData {
     return new FixedFormatSerializerImpl();
   }
 
+  @Override
+  public EdmAssistedSerializer createEdmAssistedSerializer(final ContentType contentType) throws SerializerException {
+    if (contentType.isCompatible(ContentType.APPLICATION_JSON)) {
+      return new EdmAssistedJsonSerializer(contentType);
+    }
+    throw new SerializerException("Unsupported format: " + contentType.toContentTypeString(),
+        SerializerException.MessageKeys.UNSUPPORTED_FORMAT, contentType.toContentTypeString());
+  }
+
   @Override
   public ODataHttpHandler createHandler(final ServiceMetadata serviceMetadata) {
     return new ODataHttpHandlerImpl(this, serviceMetadata);
@@ -165,5 +176,4 @@ public class ODataImpl extends OData {
     // TODO: Support more debug formats
     return new DebugResponseHelperImpl(debugFormat);
   }
-
 }

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/EdmAssistedJsonSerializer.java

@@ -47,6 +47,8 @@ import org.apache.olingo.commons.api.format.ContentType;
 import org.apache.olingo.commons.core.edm.EdmTypeInfo;
 import org.apache.olingo.commons.core.edm.primitivetype.EdmPrimitiveTypeFactory;
 import org.apache.olingo.server.api.ServiceMetadata;
+import org.apache.olingo.server.api.serializer.EdmAssistedSerializer;
+import org.apache.olingo.server.api.serializer.EdmAssistedSerializerOptions;
 import org.apache.olingo.server.api.serializer.SerializerException;
 import org.apache.olingo.server.api.serializer.SerializerException.MessageKeys;
 import org.apache.olingo.server.api.serializer.SerializerResult;
@@ -58,7 +60,7 @@ import org.apache.olingo.server.core.serializer.utils.ContextURLBuilder;
 import com.fasterxml.jackson.core.JsonFactory;
 import com.fasterxml.jackson.core.JsonGenerator;
 
-public class EdmAssistedJsonSerializer {
+public class EdmAssistedJsonSerializer implements EdmAssistedSerializer {
 
   private static final String IO_EXCEPTION_TEXT = "An I/O exception occurred.";
 
@@ -70,14 +72,16 @@ public class EdmAssistedJsonSerializer {
     this.isODataMetadataNone = ContentTypeHelper.isODataMetadataNone(contentType);
   }
 
+  @Override
   public SerializerResult entityCollection(final ServiceMetadata metadata, final EdmEntityType entityType,
-      final AbstractEntityCollection entityCollection, final ContextURL contextURL) throws SerializerException {
+      final AbstractEntityCollection entityCollection, final EdmAssistedSerializerOptions options)
-    return serialize(metadata, entityType, entityCollection, contextURL);
+      throws SerializerException {
+    return serialize(metadata, entityType, entityCollection, options == null ? null : options.getContextURL());
   }
 
   public SerializerResult entity(final ServiceMetadata metadata, final EdmEntityType entityType, final Entity entity,
-      final ContextURL contextURL) throws SerializerException {
+      final EdmAssistedSerializerOptions options) throws SerializerException {
-    return serialize(metadata, entityType, entity, contextURL);
+    return serialize(metadata, entityType, entity, options == null ? null : options.getContextURL());
   }
 
   protected SerializerResult serialize(final ServiceMetadata metadata, final EdmEntityType entityType,

lib/server-test/src/test/java/org/apache/olingo/server/core/serializer/json/EdmAssistedJsonSerializerTest.java

@@ -18,6 +18,7 @@
  */
 package org.apache.olingo.server.core.serializer.json;
 
+import java.io.IOException;
 import java.math.BigDecimal;
 import java.net.URI;
 import java.util.Arrays;
@@ -27,9 +28,9 @@ import java.util.TimeZone;
 import java.util.UUID;
 
 import org.apache.commons.io.IOUtils;
+import org.apache.olingo.commons.api.data.AbstractEntityCollection;
 import org.apache.olingo.commons.api.data.ComplexValue;
 import org.apache.olingo.commons.api.data.ContextURL;
-import org.apache.olingo.commons.api.data.ContextURL.Suffix;
 import org.apache.olingo.commons.api.data.Entity;
 import org.apache.olingo.commons.api.data.EntityCollection;
 import org.apache.olingo.commons.api.data.Link;
@@ -41,6 +42,8 @@ import org.apache.olingo.commons.api.edmx.EdmxReference;
 import org.apache.olingo.commons.api.format.ContentType;
 import org.apache.olingo.server.api.OData;
 import org.apache.olingo.server.api.ServiceMetadata;
+import org.apache.olingo.server.api.serializer.EdmAssistedSerializer;
+import org.apache.olingo.server.api.serializer.EdmAssistedSerializerOptions;
 import org.apache.olingo.server.api.serializer.SerializerException;
 import org.apache.olingo.server.tecsvc.MetadataETagSupport;
 import org.apache.olingo.server.tecsvc.provider.EdmTechProvider;
@@ -52,46 +55,38 @@ public class EdmAssistedJsonSerializerTest {
   private static final ServiceMetadata metadata = oData.createServiceMetadata(
       new EdmTechProvider(), Collections.<EdmxReference> emptyList(), null);
   private static final EdmEntityContainer entityContainer = metadata.getEdm().getEntityContainer();
-  private final EdmAssistedJsonSerializer serializer = new EdmAssistedJsonSerializer(ContentType.JSON);
+  private final EdmAssistedSerializer serializer;
 
-  @Test
+  public EdmAssistedJsonSerializerTest() throws SerializerException {
-  public void entity() throws Exception {
+    serializer = oData.createEdmAssistedSerializer(ContentType.JSON);
-    Entity entity = new Entity();
-    entity.setId(null);
-    entity.addProperty(new Property(null, "Property1", ValueType.PRIMITIVE, 1.25F));
-    final String resultString = IOUtils.toString(
-        serializer.entity(metadata, null, entity,
-            ContextURL.with().entitySetOrSingletonOrType("EntitySet").selectList("Property1")
-                .suffix(Suffix.ENTITY)
-                .build())
-            .getContent());
-    final String expectedResult =
-        "{\"@odata.context\":\"$metadata#EntitySet(Property1)/$entity\","
-        + "\"@odata.id\":null,"
-        + "\"Property1@odata.type\":\"Single\",\"Property1\":1.25"
-        + "}";
-    Assert.assertEquals(expectedResult, resultString);
   }
 
   @Test
-  public void entityWithEdm() throws Exception {
+  public void entityCollectionSimple() throws Exception {
+    Entity entity = new Entity();
+    entity.setId(null);
+    entity.addProperty(new Property(null, "Property1", ValueType.PRIMITIVE, 1.25F));
+    EntityCollection entityCollection = new EntityCollection();
+    entityCollection.getEntities().add(entity);
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#EntitySet(Property1)\","
+        + "\"value\":[{\"@odata.id\":null,\"Property1@odata.type\":\"Single\",\"Property1\":1.25}]}",
+        serialize(serializer, metadata, null, entityCollection, null));
+  }
+
+  @Test
+  public void entityCollectionWithEdm() throws Exception {
     final EdmEntitySet entitySet = entityContainer.getEntitySet("ESTwoPrim");
     Entity entity = new Entity();
     entity.setId(null);
     entity.addProperty(new Property(null, "PropertyInt16", ValueType.PRIMITIVE, (short) 1))
         .addProperty(new Property(null, "PropertyString", ValueType.PRIMITIVE, "test"))
         .addProperty(new Property(null, "AdditionalProperty", ValueType.PRIMITIVE, (byte) 42));
-    final String resultString = IOUtils.toString(
+    EntityCollection entityCollection = new EntityCollection();
-        serializer.entity(metadata, entitySet.getEntityType(), entity,
+    entityCollection.getEntities().add(entity);
-            ContextURL.with().entitySet(entitySet).suffix(Suffix.ENTITY).build())
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#ESTwoPrim\",\"value\":[{\"@odata.id\":null,"
-            .getContent());
-    final String expectedResult =
-        "{\"@odata.context\":\"$metadata#ESTwoPrim/$entity\","
-        + "\"@odata.id\":null,"
         + "\"PropertyInt16\":1,\"PropertyString\":\"test\","
-        + "\"AdditionalProperty@odata.type\":\"SByte\",\"AdditionalProperty\":42"
+        + "\"AdditionalProperty@odata.type\":\"SByte\",\"AdditionalProperty\":42}]}",
-        + "}";
+        serialize(serializer, metadata, entitySet, entityCollection, null));
-    Assert.assertEquals(expectedResult, resultString);
   }
 
   @Test
@@ -111,13 +106,7 @@ public class EdmAssistedJsonSerializerTest {
     entityCollection.getEntities().add(entity);
     entityCollection.setCount(2);
     entityCollection.setNext(URI.create("nextLink"));
-    final String resultString = IOUtils.toString(
+    Assert.assertEquals(
-        serializer.entityCollection(metadata, null, entityCollection,
-            ContextURL.with().entitySetOrSingletonOrType("EntitySet")
-                .selectList("Property0,Property1,Property2,Property3,Property4")
-                .build())
-            .getContent());
-    final String expectedResult =
         "{\"@odata.context\":\"$metadata#EntitySet(Property0,Property1,Property2,Property3,Property4)\","
             + "\"@odata.count\":2,"
             + "\"value\":[{\"@odata.id\":null,"
@@ -125,11 +114,9 @@ public class EdmAssistedJsonSerializerTest {
             + "\"Property1@odata.type\":\"Int32\",\"Property1\":1,"
             + "\"Property2@odata.type\":\"Date\",\"Property2\":\"2000-02-29\","
             + "\"Property3@odata.type\":\"DateTimeOffset\",\"Property3\":\"2000-02-29T00:00:00Z\","
-        + "\"Property4@odata.type\":\"#Collection(Boolean)\",\"Property4\":[true,false,null]"
+            + "\"Property4@odata.type\":\"#Collection(Boolean)\",\"Property4\":[true,false,null]}],"
-        + "}],"
+            + "\"@odata.nextLink\":\"nextLink\"}",
-        + "\"@odata.nextLink\":\"nextLink\""
+        serialize(serializer, metadata, null, entityCollection, null));
-        + "}";
-    Assert.assertEquals(expectedResult, resultString);
   }
 
   @Test
@@ -147,14 +134,10 @@ public class EdmAssistedJsonSerializerTest {
             + "\"Property1@odata.type\":\"Int64\",\"Property1\":\"-9223372036854775808\","
             + "\"Property2@odata.type\":\"Decimal\",\"Property2\":\"922337203.6854775807\","
             + "\"Property3@odata.type\":\"Byte\",\"Property3\":20}]}",
-        IOUtils.toString(
+        serialize(
-            new EdmAssistedJsonSerializer(
+            oData.createEdmAssistedSerializer(
-                ContentType.create(ContentType.JSON, ContentType.PARAMETER_IEEE754_COMPATIBLE, "true"))
+                ContentType.create(ContentType.JSON, ContentType.PARAMETER_IEEE754_COMPATIBLE, "true")),
-                .entityCollection(metadata, null, entityCollection,
+            metadata, null, entityCollection, null));
-                    ContextURL.with().entitySetOrSingletonOrType("EntitySet")
-                        .selectList("Property1,Property2,Property3")
-                        .build())
-                .getContent()));
   }
 
   @Test
@@ -174,23 +157,17 @@ public class EdmAssistedJsonSerializerTest {
     entity.addProperty(new Property("Namespace.ComplexType", "Property2", ValueType.COMPLEX, complexValue));
     EntityCollection entityCollection = new EntityCollection();
     entityCollection.getEntities().add(entity);
-    final String resultString = IOUtils.toString(
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#EntitySet(Property1,Property2)\","
-        serializer.entityCollection(metadata, null, entityCollection,
-            ContextURL.with().entitySetOrSingletonOrType("EntitySet").selectList("Property1,Property2").build())
-            .getContent());
-    final String expectedResult = "{\"@odata.context\":\"$metadata#EntitySet(Property1,Property2)\","
         + "\"value\":[{\"@odata.id\":null,"
         + "\"Property1@odata.type\":\"Int64\",\"Property1\":1,"
-        + "\"Property2\":{"
+        + "\"Property2\":{\"@odata.type\":\"#Namespace.ComplexType\","
-        + "\"@odata.type\":\"#Namespace.ComplexType\","
         + "\"Inner1@odata.type\":\"Decimal\",\"Inner1\":0.00010,"
-        + "\"Inner2@odata.type\":\"TimeOfDay\",\"Inner2\":\"13:00:59.999\""
+        + "\"Inner2@odata.type\":\"TimeOfDay\",\"Inner2\":\"13:00:59.999\"}}]}",
-        + "}}]}";
+        serialize(serializer, metadata, null, entityCollection, null));
-    Assert.assertEquals(expectedResult, resultString);
   }
 
   @Test
-  public void entityWithComplexCollection() throws Exception {
+  public void entityCollectionWithComplexCollection() throws Exception {
     final EdmEntitySet entitySet = entityContainer.getEntitySet("ESMixPrimCollComp");
     ComplexValue complexValue1 = new ComplexValue();
     complexValue1.getValue().add(new Property(null, "PropertyInt16", ValueType.PRIMITIVE, 1));
@@ -201,35 +178,30 @@ public class EdmAssistedJsonSerializerTest {
     ComplexValue complexValue3 = new ComplexValue();
     complexValue3.getValue().add(new Property(null, "PropertyInt16", ValueType.PRIMITIVE, 3));
     complexValue3.getValue().add(new Property(null, "PropertyString", ValueType.PRIMITIVE, "three"));
-    final Entity entity = new Entity()
+    EntityCollection entityCollection = new EntityCollection();
+    entityCollection.getEntities().add(new Entity()
         .addProperty(new Property(null, "CollPropertyComp", ValueType.COLLECTION_COMPLEX,
-            Arrays.asList(complexValue1, complexValue2, complexValue3)));
+            Arrays.asList(complexValue1, complexValue2, complexValue3))));
-    final String resultString = IOUtils.toString(
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#ESMixPrimCollComp(CollPropertyComp)\","
-        serializer.entity(metadata, entitySet.getEntityType(), entity,
+        + "\"value\":[{\"@odata.id\":null,"
-            ContextURL.with().entitySet(entitySet).selectList("CollPropertyComp").build())
-            .getContent());
-    final String expectedResult = "{\"@odata.context\":\"$metadata#ESMixPrimCollComp(CollPropertyComp)\","
-        + "\"@odata.id\":null,"
         + "\"CollPropertyComp\":["
         + "{\"PropertyInt16\":1,\"PropertyString\":\"one\"},"
         + "{\"PropertyInt16\":2,\"PropertyString\":\"two\"},"
-        + "{\"PropertyInt16\":3,\"PropertyString\":\"three\"}]}";
+        + "{\"PropertyInt16\":3,\"PropertyString\":\"three\"}]}]}",
-    Assert.assertEquals(expectedResult, resultString);
+        serialize(serializer, metadata, entitySet, entityCollection, "CollPropertyComp"));
   }
 
   @Test
-  public void entityWithEmptyCollection() throws Exception {
+  public void entityCollectionWithEmptyCollection() throws Exception {
     final EdmEntitySet entitySet = entityContainer.getEntitySet("ESMixPrimCollComp");
-    final Entity entity = new Entity()
+    EntityCollection entityCollection = new EntityCollection();
+    entityCollection.getEntities().add(new Entity()
         .addProperty(new Property(null, "CollPropertyString", ValueType.COLLECTION_PRIMITIVE,
-            Collections.emptyList()));
+            Collections.emptyList())));
     Assert.assertEquals(
         "{\"@odata.context\":\"$metadata#ESMixPrimCollComp(CollPropertyString)\","
-            + "\"@odata.id\":null,\"CollPropertyString\":[]}",
+            + "\"value\":[{\"@odata.id\":null,\"CollPropertyString\":[]}]}",
-        IOUtils.toString(
+        serialize(serializer, metadata, entitySet, entityCollection, "CollPropertyString"));
-            serializer.entity(metadata, entitySet.getEntityType(), entity,
-                ContextURL.with().entitySet(entitySet).selectList("CollPropertyString").build())
-                .getContent()));
   }
 
   @Test
@@ -248,20 +220,13 @@ public class EdmAssistedJsonSerializerTest {
     entity.getNavigationLinks().add(link);
     EntityCollection entityCollection = new EntityCollection();
     entityCollection.getEntities().add(entity);
-    final String resultString = IOUtils.toString(
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#EntitySet(Property1,NavigationProperty(Related1))\","
-        serializer.entityCollection(metadata, null, entityCollection,
-            ContextURL.with().entitySetOrSingletonOrType("EntitySet")
-                .selectList("Property1,NavigationProperty(Related1)").build())
-            .getContent());
-    final String expectedResult =
-        "{\"@odata.context\":\"$metadata#EntitySet(Property1,NavigationProperty(Related1))\","
         + "\"value\":[{\"@odata.id\":null,"
         + "\"Property1@odata.type\":\"Int16\",\"Property1\":1,"
         + "\"NavigationProperty\":["
         + "{\"@odata.id\":null,\"Related1@odata.type\":\"Double\",\"Related1\":1.5},"
-        + "{\"@odata.id\":null,\"Related1@odata.type\":\"Double\",\"Related1\":2.75}"
+        + "{\"@odata.id\":null,\"Related1@odata.type\":\"Double\",\"Related1\":2.75}]}]}",
-        + "]}]}";
+        serialize(serializer, metadata, null, entityCollection, "Property1,NavigationProperty(Related1)"));
-    Assert.assertEquals(expectedResult, resultString);
   }
 
   @Test
@@ -277,17 +242,12 @@ public class EdmAssistedJsonSerializerTest {
     link.setTitle("NavPropertyETAllPrimOne");
     link.setInlineEntity(target);
     entity.getNavigationLinks().add(link);
-    final String resultString = IOUtils.toString(
+    EntityCollection entityCollection = new EntityCollection();
-        serializer.entity(metadata, entitySet.getEntityType(), entity,
+    entityCollection.getEntities().add(entity);
-            ContextURL.with().entitySet(entitySet).suffix(Suffix.ENTITY).build())
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#ESTwoPrim\",\"value\":[{\"@odata.id\":null,"
-            .getContent());
-    final String expectedResult =
-        "{\"@odata.context\":\"$metadata#ESTwoPrim/$entity\","
-        + "\"@odata.id\":null,"
         + "\"PropertyInt16\":42,\"PropertyString\":\"test\","
-        + "\"NavPropertyETAllPrimOne\":{\"@odata.id\":null,\"PropertyInt16\":2,\"PropertyByte\":3}"
+        + "\"NavPropertyETAllPrimOne\":{\"@odata.id\":null,\"PropertyInt16\":2,\"PropertyByte\":3}}]}",
-        + "}";
+        serialize(serializer, metadata, entitySet, entityCollection, null));
-    Assert.assertEquals(expectedResult, resultString);
   }
 
   @Test
@@ -304,64 +264,70 @@ public class EdmAssistedJsonSerializerTest {
     entity.setMediaContentSource(URI.create("media"));
     entity.addProperty(new Property(null, "Property1", ValueType.PRIMITIVE,
         UUID.fromString("12345678-ABCD-1234-CDEF-123456789012")));
-    final ContextURL contextURL = ContextURL.with().entitySetOrSingletonOrType("EntitySet").selectList("Property1")
+    EntityCollection entityCollection = new EntityCollection();
-        .suffix(Suffix.ENTITY).build();
+    entityCollection.getEntities().add(entity);
-    final String resultString = IOUtils.toString(serializer.entity(metadata, null, entity, contextURL).getContent());
+    Assert.assertEquals("{\"@odata.context\":\"$metadata#EntitySet(Property1)\","
-    final String expectedResult =
+        + "\"@odata.metadataEtag\":\"W/\\\"42\\\"\",\"value\":[{"
-        "{\"@odata.context\":\"$metadata#EntitySet(Property1)/$entity\","
-        + "\"@odata.metadataEtag\":\"W/\\\"42\\\"\","
         + "\"@odata.etag\":\"W/\\\"1000\\\"\","
         + "\"@odata.type\":\"#Namespace.EntityType\","
         + "\"@odata.id\":\"ID\","
         + "\"Property1@odata.type\":\"Guid\",\"Property1\":\"12345678-abcd-1234-cdef-123456789012\","
         + "\"@odata.editLink\":\"editLink\","
-        + "\"@odata.mediaReadLink\":\"editLink/$value\""
+        + "\"@odata.mediaReadLink\":\"editLink/$value\"}]}",
-        + "}";
+        serialize(serializer, metadata, null, entityCollection, null));
-    Assert.assertEquals(expectedResult, resultString);
 
-    Assert.assertEquals("{\"Property1\":\"12345678-abcd-1234-cdef-123456789012\"}",
+    Assert.assertEquals("{\"value\":[{\"Property1\":\"12345678-abcd-1234-cdef-123456789012\"}]}",
-        IOUtils.toString(new EdmAssistedJsonSerializer(ContentType.JSON_NO_METADATA)
+        serialize(oData.createEdmAssistedSerializer(ContentType.JSON_NO_METADATA), metadata,
-            .entity(metadata, null, entity, contextURL).getContent()));
+            null, entityCollection, null));
   }
 
   @Test(expected = SerializerException.class)
   public void enumType() throws Exception {
-    serializer.entity(metadata, null,
+    EntityCollection entityCollection = new EntityCollection();
-        new Entity().addProperty(new Property(null, "Property1", ValueType.ENUM, 42)), null);
+    entityCollection.getEntities().add(
+        new Entity().addProperty(new Property(null, "Property1", ValueType.ENUM, 42)));
+    serializer.entityCollection(metadata, null, entityCollection, null);
   }
 
   @Test(expected = SerializerException.class)
   public void collectionEnumType() throws Exception {
-    serializer.entity(metadata, null,
+    EntityCollection entityCollection = new EntityCollection();
-        new Entity().addProperty(new Property(null, "Property1", ValueType.COLLECTION_ENUM, Arrays.asList(42))),
+    entityCollection.getEntities().add(
-        null);
+        new Entity().addProperty(new Property(null, "Property1", ValueType.COLLECTION_ENUM, Arrays.asList(42))));
+    serializer.entityCollection(metadata, null, entityCollection, null);
   }
 
   @Test(expected = SerializerException.class)
   public void geoType() throws Exception {
-    serializer.entity(metadata, null,
+    EntityCollection entityCollection = new EntityCollection();
-        new Entity().addProperty(new Property(null, "Property1", ValueType.GEOSPATIAL, 1)), null);
+    entityCollection.getEntities().add(
+        new Entity().addProperty(new Property(null, "Property1", ValueType.GEOSPATIAL, 1)));
+    serializer.entityCollection(metadata, null, entityCollection, null);
   }
 
   @Test(expected = SerializerException.class)
   public void unsupportedType() throws Exception {
-    serializer.entity(metadata, null,
+    EntityCollection entityCollection = new EntityCollection();
-        new Entity().addProperty(new Property(null, "Property1", ValueType.PRIMITIVE, TimeZone.getDefault())),
+    entityCollection.getEntities().add(
-        null);
+        new Entity().addProperty(new Property(null, "Property1", ValueType.PRIMITIVE, TimeZone.getDefault())));
+    serializer.entityCollection(metadata, null, entityCollection, null);
   }
 
   @Test(expected = SerializerException.class)
   public void wrongValueForType() throws Exception {
-    serializer.entity(metadata, null,
+    EntityCollection entityCollection = new EntityCollection();
-        new Entity().addProperty(new Property("Edm.SByte", "Property1", ValueType.PRIMITIVE, "-1")),
+    entityCollection.getEntities().add(
-        null);
+        new Entity().addProperty(new Property("Edm.SByte", "Property1", ValueType.PRIMITIVE, "-1")));
+    serializer.entityCollection(metadata, null, entityCollection, null);
   }
 
   @Test(expected = SerializerException.class)
   public void wrongValueForPropertyFacet() throws Exception {
-    serializer.entity(metadata, entityContainer.getEntitySet("ESAllPrim").getEntityType(),
+    EntityCollection entityCollection = new EntityCollection();
+    entityCollection.getEntities().add(
         new Entity().addProperty(
-            new Property(null, "PropertyDecimal", ValueType.PRIMITIVE, BigDecimal.ONE.scaleByPowerOfTen(-11))),
+            new Property(null, "PropertyDecimal", ValueType.PRIMITIVE, BigDecimal.ONE.scaleByPowerOfTen(-11))));
+    serializer.entityCollection(metadata, entityContainer.getEntitySet("ESAllPrim").getEntityType(), entityCollection,
         null);
   }
 
@@ -373,10 +339,38 @@ public class EdmAssistedJsonSerializerTest {
     ComplexValue complexValue = new ComplexValue();
     complexValue.getValue().add(new Property(null, "PropertyComp", ValueType.COMPLEX,
         innerComplexValue));
-    serializer.entity(metadata, entityContainer.getEntitySet("ESKeyNav").getEntityType(),
+    EntityCollection entityCollection = new EntityCollection();
+    entityCollection.getEntities().add(
         new Entity().addProperty(
             new Property(null, "CollPropertyComp", ValueType.COLLECTION_COMPLEX,
-                Collections.singletonList(complexValue))),
+                Collections.singletonList(complexValue))));
+    serializer.entityCollection(metadata, entityContainer.getEntitySet("ESKeyNav").getEntityType(), entityCollection,
         null);
   }
+
+  private String serialize(final EdmAssistedSerializer serializer, final ServiceMetadata metadata,
+      final EdmEntitySet edmEntitySet, final AbstractEntityCollection entityCollection, final String selectList)
+      throws SerializerException, IOException {
+    ContextURL.Builder contextURLBuilder = ContextURL.with();
+    contextURLBuilder = edmEntitySet == null ?
+        contextURLBuilder.entitySetOrSingletonOrType("EntitySet") :
+        contextURLBuilder.entitySet(edmEntitySet);
+    if (selectList == null) {
+      if (edmEntitySet == null) {
+        StringBuilder names = new StringBuilder();
+        for (final Property property : entityCollection.iterator().next().getProperties()) {
+          names.append(names.length() > 0 ? ',' : "").append(property.getName());
+        }
+        contextURLBuilder = contextURLBuilder.selectList(names.toString());
+      }
+    } else {
+      contextURLBuilder = contextURLBuilder.selectList(selectList);
+    }
+    return IOUtils.toString(
+        serializer.entityCollection(metadata,
+            edmEntitySet == null ? null : edmEntitySet.getEntityType(),
+            entityCollection,
+            EdmAssistedSerializerOptions.with().contextURL(contextURLBuilder.build()).build())
+            .getContent());
+  }
 }