Exposed underlying CosmosElements on item QueryResponse<T> using gene… (

#1018)

* Exposed underlying CosmosElements on item QueryResponse<T> using generic type parameter.

* Applied PR comment:
- Switching to using 'as' rather than 'is' to save on reflection.

* Applying PR comment:
- Changing 'as' and 'null' check to inline 'is'.

* Reverted to a specific type check for CosmosElement.
- Trying to do the generic cast in all cases leads to CosmosElements being returned for QueryResponse<dynamic>.Resource and QueryResponse<object>.Resource, etc.
- This gives us the least change to the behavior for users that might do these sorts of casts.

Microsoft.Azure.Cosmos/src/Query/v3Query/QueryResponse.cs

@@ -189,12 +189,19 @@ public override IEnumerable<T> Resource
             {
                 if (this.resources == null)
                 {
-                    this.resources = CosmosElementSerializer.Deserialize<T>(
-                        this.QueryHeaders.ContainerRid,
-                        this.cosmosElements,
-                        this.QueryHeaders.ResourceType,
-                        this.jsonSerializer,
-                        this.serializationOptions);
+                    if (typeof(T) == typeof(CosmosElement))
+                    {
+                        this.resources = this.cosmosElements.Cast<T>();
+                    }
+                    else
+                    {
+                        this.resources = CosmosElementSerializer.Deserialize<T>(
+                            this.QueryHeaders.ContainerRid,
+                            this.cosmosElements,
+                            this.QueryHeaders.ResourceType,
+                            this.jsonSerializer,
+                            this.serializationOptions);
+                    }
                 }
 
                 return this.resources;

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosQueryUnitTests.cs

@@ -11,6 +11,7 @@ namespace Microsoft.Azure.Cosmos.Tests
     using System.Net.Http;
     using System.Threading;
     using System.Threading.Tasks;
+    using Microsoft.Azure.Cosmos.CosmosElements;
     using Microsoft.Azure.Cosmos.Query;
     using Microsoft.Azure.Cosmos.Query.Core.ExecutionComponent;
     using Microsoft.Azure.Cosmos.Query.Core.ExecutionContext;
@@ -58,6 +59,84 @@ public void VerifyCosmosQueryResponseStream()
             }
         }
 
+        [TestMethod]
+        public void VerifyItemQueryResponseResult()
+        {
+            string contianerRid = "mockContainerRid";
+            (QueryResponseCore response, IList<ToDoItem> items) factoryResponse = QueryResponseMessageFactory.Create(
+                       itemIdPrefix: $"TestPage",
+                       continuationToken: "SomeContinuationToken",
+                       collectionRid: contianerRid,
+                       itemCount: 100);
+
+            QueryResponseCore responseCore = factoryResponse.response;
+            List<CosmosElement> cosmosElements = new List<CosmosElement>(responseCore.CosmosElements);
+
+            QueryResponse queryResponse = QueryResponse.CreateSuccess(
+                        result: cosmosElements,
+                        count: cosmosElements.Count,
+                        responseLengthBytes: responseCore.ResponseLengthBytes,
+                        responseHeaders: new CosmosQueryResponseMessageHeaders(
+                            responseCore.ContinuationToken,
+                            responseCore.DisallowContinuationTokenMessage,
+                            ResourceType.Document,
+                            contianerRid)
+                        {
+                            RequestCharge = responseCore.RequestCharge,
+                            ActivityId = responseCore.ActivityId
+                        },
+                        diagnostics: null);
+
+            QueryResponse<ToDoItem> itemQueryResponse = QueryResponseMessageFactory.CreateQueryResponse<ToDoItem>(queryResponse);
+            List<ToDoItem> resultItems = new List<ToDoItem>(itemQueryResponse.Resource);
+            ToDoItemComparer comparer = new ToDoItemComparer();
+
+            Assert.AreEqual(factoryResponse.items.Count, resultItems.Count);
+            for (int i = 0; i < factoryResponse.items.Count; i++)
+            {
+                Assert.AreNotSame(factoryResponse.items[i], resultItems[i]);
+                Assert.AreEqual(0, comparer.Compare(factoryResponse.items[i], resultItems[i]));
+            }
+        }
+
+        [TestMethod]
+        public void VerifyItemQueryResponseCosmosElements()
+        {
+            string containerRid = "mockContainerRid";
+            (QueryResponseCore response, IList<ToDoItem> items) factoryResponse = QueryResponseMessageFactory.Create(
+                       itemIdPrefix: $"TestPage",
+                       continuationToken: "SomeContinuationToken",
+                       collectionRid: containerRid,
+                       itemCount: 100);
+
+            QueryResponseCore responseCore = factoryResponse.response;
+            List<CosmosElement> cosmosElements = new List<CosmosElement>(responseCore.CosmosElements);
+
+            QueryResponse queryResponse = QueryResponse.CreateSuccess(
+                        result: cosmosElements,
+                        count: cosmosElements.Count,
+                        responseLengthBytes: responseCore.ResponseLengthBytes,
+                        responseHeaders: new CosmosQueryResponseMessageHeaders(
+                            responseCore.ContinuationToken,
+                            responseCore.DisallowContinuationTokenMessage,
+                            ResourceType.Document,
+                            containerRid)
+                        {
+                            RequestCharge = responseCore.RequestCharge,
+                            ActivityId = responseCore.ActivityId
+                        },
+                        diagnostics: null);
+
+            QueryResponse<CosmosElement> itemQueryResponse = QueryResponseMessageFactory.CreateQueryResponse<CosmosElement>(queryResponse);
+            List<CosmosElement> resultItems = new List<CosmosElement>(itemQueryResponse.Resource);
+
+            Assert.AreEqual(cosmosElements.Count, resultItems.Count);
+            for (int i = 0; i < cosmosElements.Count; i++)
+            {
+                Assert.AreSame(cosmosElements[i], resultItems[i]);
+            }
+        }
+
         [TestMethod]
         public async Task TestCosmosQueryExecutionComponentOnFailure()
         {

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Query/QueryResponseMessageFactory.cs

@@ -135,6 +135,12 @@ public static QueryResponseCore CreateQueryResponse(
             return message;
         }
 
+        public static QueryResponse<TItem> CreateQueryResponse<TItem>(
+            QueryResponse queryResponse)
+        {
+            return QueryResponse<TItem>.CreateResponse<TItem>(queryResponse, cosmosSerializer);
+        }
+
         public static QueryResponseCore CreateFailureResponse(
             HttpStatusCode httpStatusCode,
             SubStatusCodes subStatusCodes,