Handle null values properly during deserialization

Havret · Mar 28, 2022 · c4194f4 · c4194f4
1 parent 0876f3e
commit c4194f4
Show file tree

Hide file tree

Showing 2 changed files with 32 additions and 3 deletions.
diff --git a/src/Protobuf.System.Text.Json/ProtobufConverter.cs b/src/Protobuf.System.Text.Json/ProtobufConverter.cs
@@ -55,14 +55,19 @@ private static Func<FieldDescriptor, string> GetConvertNameFunc(JsonNamingPolicy
         return descriptor => descriptor.PropertyName;
     }
 
-    public override T Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    public override T? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
-        var obj = new T();
-
+        if (reader.TokenType == JsonTokenType.Null)
+        {
+            return null;
+        }
+
         if (reader.TokenType != JsonTokenType.StartObject)
         {
             throw new JsonException($"The JSON value could not be converted to {typeToConvert}.");
         }
+
+        var obj = new T();
 
         // Process all properties.
         while (true)

diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithComplexPropertyTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithComplexPropertyTests.cs
@@ -1,5 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
+using System.Text.Json.Serialization;
 using Protobuf.System.Text.Json.Tests.Utils;
 using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
@@ -45,6 +46,29 @@ public void Should_deserialize_message_with_complex_property()
 
         var jsonSerializerOptions = TestHelper.CreateJsonSerializerOptions();
 
+        // Act
+        var serialized = JsonSerializer.Serialize(msg, jsonSerializerOptions);
+        var deserialized = JsonSerializer.Deserialize<MessageWithComplexProperty>(serialized, jsonSerializerOptions);
+
+        // Assert
+        deserialized.ShouldBeEquivalentTo(msg);
+    }
+
+    [Fact]
+    public void Should_deserialize_message_with_complex_property_when_no_value_is_set()
+    {
+        // Arrange
+        var msg = new MessageWithComplexProperty
+        {
+            NestedMessage = null
+        };
+
+        var jsonSerializerOptions = TestHelper.CreateJsonSerializerOptions();
+
+        // make sure the value won't be ignored
+        jsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.Never;
+
+
         // Act
         var serialized = JsonSerializer.Serialize(msg, jsonSerializerOptions);
         var deserialized = JsonSerializer.Deserialize<MessageWithComplexProperty>(serialized, jsonSerializerOptions);