Merge pull request #885 from martincostello/Set-Content-Length

Specify Content-Length when serializing JSON with System.Text.Json

Refit.Tests/SerializedContentTests.cs

@@ -146,5 +146,25 @@ public async Task StreamDeserialization_UsingSystemTextJsonContentSerializer()
             Assert.Equal(model.ShortNameForAlias, result.ShortNameForAlias);
             Assert.Equal(model.ShortNameForJsonProperty, result.ShortNameForJsonProperty);
         }
+
+        [Fact]
+        public async Task StreamDeserialization_UsingSystemTextJsonContentSerializer_SetsCorrectHeaders()
+        {
+            var model = new TestAliasObject
+            {
+                ShortNameForAlias = nameof(StreamDeserialization_UsingSystemTextJsonContentSerializer),
+                ShortNameForJsonProperty = nameof(TestAliasObject)
+            };
+
+            var serializer = new SystemTextJsonContentSerializer();
+
+            var json = await serializer.SerializeAsync(model);
+
+            Assert.NotNull(json.Headers.ContentLength);
+            Assert.True(json.Headers.ContentLength.Value > 0);
+            Assert.NotNull(json.Headers.ContentType);
+            Assert.Equal("utf-8", json.Headers.ContentType.CharSet);
+            Assert.Equal("application/json", json.Headers.ContentType.MediaType);
+        }
     }
 }

Refit/SystemTextJsonContentSerializer.cs

@@ -44,10 +44,13 @@ public Task<HttpContent> SerializeAsync<T>(T item)
 
             JsonSerializer.Serialize(utf8JsonWriter, item, jsonSerializerOptions);
 
-            var content = new StreamContent(utf8BufferWriter.DetachStream())
+            var stream = utf8BufferWriter.DetachStream();
+
+            var content = new StreamContent(stream)
             {
                 Headers =
                 {
+                    ContentLength = stream.Length,
                     ContentType = new MediaTypeHeaderValue("application/json") { CharSet = Encoding.UTF8.WebName }
                 }
             };