Return null if cosmos db input can't find item

extensions/Worker.Extensions.CosmosDB/src/CosmosDBConverter.cs

@@ -58,6 +58,10 @@ private async ValueTask<ConversionResult> ConvertFromBindingDataAsync(ConverterC
 
                 return ConversionResult.Success(result);
             }
+            catch (CosmosException ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
+            {
+                return ConversionResult.Success(null);
+            }
             catch (Exception ex)
             {
                 return ConversionResult.Failed(ex);

release_notes.md

@@ -7,6 +7,7 @@
 ### Microsoft.Azure.Functions.Worker (metapackage) <version>
 
 - `AZURE_FUNCTIONS_` environment variables are now loaded correctly when using `FunctionsApplicationBuilder`. (#2878)
+- Return null when cosmos db input can't find a document (#2545)
 
 ### Microsoft.Azure.Functions.Worker.Core <version>
 

test/Worker.Extensions.Tests/Cosmos/CosmosDBConverterTests.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Net;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -359,14 +360,18 @@ public async Task ConvertAsync_CosmosContainerIsNull_ThrowsException_ReturnsFail
             Assert.Equal($"Unable to create Cosmos container client for 'myContainer'.", conversionResult.Error.Message);
         }
 
-        [Fact]
-        public async Task ConvertAsync_POCO_IdProvided_StatusNot200_ThrowsException_ReturnsFailure()
+        [Theory]
+        [InlineData(HttpStatusCode.Conflict)]
+        [InlineData(HttpStatusCode.Forbidden)]
+        [InlineData(HttpStatusCode.InternalServerError)]
+        [InlineData(HttpStatusCode.BadRequest)]
+        public async Task ConvertAsync_POCO_IdProvided_NotSuccessStatus_ThrowsException_ReturnsFailure(HttpStatusCode httpStatusCode)
         {
             object grpcModelBindingData = GrpcTestHelper.GetTestGrpcModelBindingData(GetTestBinaryData(id: "1", partitionKey: "1"), "CosmosDB");
             var context = new TestConverterContext(typeof(ToDoItem), grpcModelBindingData);
 
             var mockResponse = new Mock<ResponseMessage>();
-            var cosmosException = new CosmosException("test failure", System.Net.HttpStatusCode.NotFound, 0, "test", 0);
+            var cosmosException = new CosmosException("test failure", httpStatusCode, 0, "test", 0);
             mockResponse.Setup(x => x.EnsureSuccessStatusCode()).Throws(cosmosException);
 
             var mockContainer = new Mock<Container>();
@@ -384,6 +389,32 @@ public async Task ConvertAsync_POCO_IdProvided_StatusNot200_ThrowsException_Retu
             Assert.Equal("test failure", conversionResult.Error.Message);
         }
 
+        [Fact]
+        public async Task ConvertAsync_POCO_IdProvided_Status404_ThrowsException_ReturnsFailure()
+        {
+            object grpcModelBindingData = GrpcTestHelper.GetTestGrpcModelBindingData(GetTestBinaryData(id: "1", partitionKey: "1"), "CosmosDB");
+            var context = new TestConverterContext(typeof(ToDoItem), grpcModelBindingData);
+
+            var mockResponse = new Mock<ResponseMessage>();
+            mockResponse.Setup(x => x.IsSuccessStatusCode).Returns(false);
+            var cosmosException = new CosmosException("test failure", HttpStatusCode.NotFound, 0, "test", 0);
+            mockResponse.Setup(x => x.EnsureSuccessStatusCode()).Throws(cosmosException);
+
+            var mockContainer = new Mock<Container>();
+            mockContainer
+                .Setup(m => m.ReadItemStreamAsync(It.IsAny<string>(), It.IsAny<PartitionKey>(), null, default))
+                .ReturnsAsync(mockResponse.Object);
+
+            _mockCosmosClient
+                .Setup(m => m.GetContainer(It.IsAny<string>(), It.IsAny<string>()))
+                .Returns(mockContainer.Object);
+
+            var conversionResult = await _cosmosDBConverter.ConvertAsync(context);
+
+            Assert.Equal(ConversionStatus.Succeeded, conversionResult.Status);
+            Assert.Null(conversionResult.Value);
+        }
+
         private BinaryData GetTestBinaryData(string db = "testDb", string container = "testContainer", string connection = "cosmosConnection", string id = "", string partitionKey = "", string query = "", string location = "", string queryParams = "{}")
         {
             string jsonData = $@"{{