If 'out of order properties' enabled, allow type discriminator on JSONB types (#5932)

onionhammer · NinoFloris · roji · web-flow · commit 604c00c4ab5f · 2024-11-18T16:35:08.000+02:00
Fixes #5937 Co-authored-by: Nino Floris <mail@ninofloris.com> Co-authored-by: Shay Rojansky <roji@roji.org>
diff --git a/Directory.Packages.props b/Directory.Packages.props
@@ -5,7 +5,7 @@
     <PackageVersion Include="OpenTelemetry.API" Version="1.7.0" />
 
     <!-- Compatibility -->
-    <PackageVersion Include="System.Text.Json" Version="8.0.5" />
+    <PackageVersion Include="System.Text.Json" Version="9.0.0" />
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="8.0.1" />
     <PackageVersion Include="System.Runtime.CompilerServices.Unsafe" Version="6.0.0" />
 
diff --git a/src/Npgsql/Internal/ResolverFactories/JsonDynamicTypeInfoResolverFactory.cs b/src/Npgsql/Internal/ResolverFactories/JsonDynamicTypeInfoResolverFactory.cs
@@ -94,9 +94,15 @@ void AddUserMappings(bool jsonb, Type[] clrTypes)
                     if (!jsonType.IsValueType && jsonTypeInfo.PolymorphismOptions is not null)
                     {
                         foreach (var derived in jsonTypeInfo.PolymorphismOptions.DerivedTypes)
+                        {
+                            // For jsonb we can't properly support polymorphic serialization unless the SerializerOptions.AllowOutOfOrderMetadataProperties is `true`.
+                            // If `jsonb` AND `AllowOutOfOrderMetadataProperties` is `false`, use `derived.DerivedType` as the base type for the converter,
+                            // this causes STJ to stop serializing the "$type" field; essentially disabling the feature.
+                            var baseType = jsonb && !serializerOptions.AllowOutOfOrderMetadataProperties ? derived.DerivedType : jsonType;
                             dynamicMappings.AddMapping(derived.DerivedType, dataTypeName,
                                 factory: (options, mapping, _) => mapping.CreateInfo(options,
-                                    CreateSystemTextJsonConverter(mapping.Type, jsonb, options.TextEncoding, serializerOptions, jsonType)));
+                                    CreateSystemTextJsonConverter(mapping.Type, jsonb, options.TextEncoding, serializerOptions, baseType)));
+                        }
                     }
                 }
                 mappings.AddRange(dynamicMappings.ToTypeInfoMappingCollection());
@@ -116,9 +122,10 @@ void AddUserMappings(bool jsonb, Type[] clrTypes)
             {
                 var jsonb = dataTypeName == DataTypeNames.Jsonb;
 
-                // For jsonb we can't properly support polymorphic serialization unless we do quite some additional work
-                // so we default to mapping.Type instead (exact types will never serialize their "$type" fields, essentially disabling the feature).
-                var baseType = jsonb ? mapping.Type : typeof(object);
+                // For jsonb we can't properly support polymorphic serialization unless the SerializerOptions.AllowOutOfOrderMetadataProperties is `true`.
+                // If `jsonb` AND `AllowOutOfOrderMetadataProperties` is `false`, use `mapping.Type` as the base type for the converter,
+                // this causes STJ to stop serializing the "$type" field; essentially disabling the feature.
+                var baseType = jsonb && !SerializerOptions.AllowOutOfOrderMetadataProperties ? mapping.Type : typeof(object);
 
                 return mapping.CreateInfo(options,
                     CreateSystemTextJsonConverter(mapping.Type, jsonb, options.TextEncoding, SerializerOptions, baseType));
diff --git a/src/Npgsql/Npgsql.csproj b/src/Npgsql/Npgsql.csproj
@@ -22,9 +22,9 @@
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net8.0' ">
     <PackageReference Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" PrivateAssets="All" />
+    <PackageReference Include="System.Text.Json" /> <!-- For AllowOutOfOrderMetadataProperties -->
   </ItemGroup>
 
-
   <ItemGroup Condition=" '$(TargetFramework)' == 'net6.0' ">
     <PackageReference Include="System.Text.Json" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" />
diff --git a/test/Npgsql.Tests/Types/JsonDynamicTests.cs b/test/Npgsql.Tests/Types/JsonDynamicTests.cs
