Support JsonConverterFactory with src-gen

[steveharter]

Addresses #58267

Expected to be ported to 6.0.

Source gen example for value types (indentation issues included):
note: usage of GetConverterFromFactory()

internalpartialclassMetadataAndSerializationContext{privateglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory>?_StructWithCustomConverterFactory;publicglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory>StructWithCustomConverterFactory{get{if(_StructWithCustomConverterFactory==null){global::System.Text.Json.Serialization.JsonConverter?customConverter;if(Options.Converters.Count>0&&(customConverter=GetRuntimeProvidedCustomConverter(typeof(global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory)))!=null){_StructWithCustomConverterFactory=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory>(Options,customConverter);}else{global::System.Text.Json.Serialization.JsonConverterconverter=this.GetConverterFromFactory(typeof(global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory),newglobal::System.Text.Json.SourceGeneration.Tests.CustomConverterFactory());global::System.TypetypeToConvert=typeof(global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory);if(!converter.CanConvert(typeToConvert)){global::System.Type?underlyingType=global::System.Nullable.GetUnderlyingType(typeToConvert);if(underlyingType!=null&&converter.CanConvert(underlyingType)){// Allow nullable handling to forward to the underlying type's converter.converter=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.GetNullableConverter<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory>(this.StructWithCustomConverterFactory)!;converter=((global::System.Text.Json.Serialization.JsonConverterFactory)converter).CreateConverter(typeToConvert,Options)!;}else{thrownewglobal::System.InvalidOperationException($"The converter '{converter.GetType()}' is not compatible with the type '{typeToConvert}'.");}}_StructWithCustomConverterFactory=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverterFactory>(Options,converter);}}return_StructWithCustomConverterFactory;}}}

and for reference types:

internalpartialclassMetadataAndSerializationContext{privateglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>?_ClassWithCustomConverterFactory;publicglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>ClassWithCustomConverterFactory{get{if(_ClassWithCustomConverterFactory==null){global::System.Text.Json.Serialization.JsonConverter?customConverter;if(Options.Converters.Count>0&&(customConverter=GetRuntimeProvidedCustomConverter(typeof(global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory)))!=null){_ClassWithCustomConverterFactory=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>(Options,customConverter);}else{global::System.Text.Json.Serialization.JsonConverterconverter=this.GetConverterFromFactory(typeof(global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory),newglobal::System.Text.Json.SourceGeneration.Tests.CustomConverterFactory());global::System.TypetypeToConvert=typeof(global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory);if(!converter.CanConvert(typeToConvert)){thrownewglobal::System.InvalidOperationException($"The converter '{converter.GetType()}' is not compatible with the type '{typeToConvert}'.");}_ClassWithCustomConverterFactory=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>(Options,converter);}}return_ClassWithCustomConverterFactory;}}}

and for properties with factories:

properties[0]=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreatePropertyInfo<global::System.Text.Json.SourceGeneration.Tests.SampleEnum>(
...converter: jsonContext.GetConverterFromFactory<global::System.Text.Json.SourceGeneration.Tests.SampleEnum>(newglobal::System.Text.Json.Serialization.JsonStringEnumConverter()),

and the new helper methods (optionally generated)

privateglobal::System.Text.Json.Serialization.JsonConverter<T>GetConverterFromFactory<T>(global::System.Text.Json.Serialization.JsonConverterFactoryfactory){return(global::System.Text.Json.Serialization.JsonConverter<T>)GetConverterFromFactory(typeof(T),factory);}privateglobal::System.Text.Json.Serialization.JsonConverterGetConverterFromFactory(global::System.Typetype,global::System.Text.Json.Serialization.JsonConverterFactoryfactory){global::System.Text.Json.Serialization.JsonConverter?converter=factory.CreateConverter(type,Options);if(converter==null||converterisglobal::System.Text.Json.Serialization.JsonConverterFactory){thrownewglobal::System.InvalidOperationException($"The converter '{factory.GetType()}' cannot return null or a JsonConverterFactory instance.");}returnconverter;}

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Issue Details

---

Addresses #58267

Expected to be ported to 6.0.

Source gen example for value types (indentation issues included):

// <auto-generated/>
#nullable enable
namespaceSystem.Text.Json.SourceGeneration.Tests{internalpartialclassMetadataContext{privateglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter>?_StructWithCustomConverter;publicglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter>StructWithCustomConverter{get{if(_StructWithCustomConverter==null){global::System.Text.Json.Serialization.JsonConverter?customConverter;if(Options.Converters.Count>0&&(customConverter=GetRuntimeProvidedCustomConverter(typeof(global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter)))!=null){_StructWithCustomConverter=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter>(Options,customConverter);}else{global::System.Text.Json.Serialization.JsonConverterconverter=newglobal::System.Text.Json.SourceGeneration.Tests.CustomConverter_StructWithCustomConverter();global::System.TypetypeToConvert=typeof(global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter);if(!converter.CanConvert(typeToConvert)){global::System.Type?underlyingType=global::System.Nullable.GetUnderlyingType(typeToConvert);if(underlyingType!=null&&converter.CanConvert(underlyingType)){// Allow nullable handling to forward to the underlying type's converter.converter=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.GetNullableConverter<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter>(this.StructWithCustomConverter)!;}else{thrownewglobal::System.InvalidOperationException($"The converter '{converter.GetType()}' is not compatible with the type '{typeToConvert}'.");}}elseif(converterisglobal::System.Text.Json.Serialization.JsonConverterFactoryfactory){global::System.Text.Json.Serialization.JsonConverter?actualConverter=factory.CreateConverter(typeToConvert,Options);if(actualConverter==null||actualConverterisglobal::System.Text.Json.Serialization.JsonConverterFactory){thrownewglobal::System.InvalidOperationException($"JsonConverterFactory '{factory.GetType()}' cannot return a 'null' or 'JsonConverterFactory' value.");}converter=actualConverter;}_StructWithCustomConverter=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.StructWithCustomConverter>(Options,converter);}}return_StructWithCustomConverter;}}}}

and for reference types:

// <auto-generated/>
#nullable enable
namespaceSystem.Text.Json.SourceGeneration.Tests{internalpartialclassMetadataContext{privateglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>?_ClassWithCustomConverterFactory;publicglobal::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>ClassWithCustomConverterFactory{get{if(_ClassWithCustomConverterFactory==null){global::System.Text.Json.Serialization.JsonConverter?customConverter;if(Options.Converters.Count>0&&(customConverter=GetRuntimeProvidedCustomConverter(typeof(global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory)))!=null){_ClassWithCustomConverterFactory=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>(Options,customConverter);}else{global::System.Text.Json.Serialization.JsonConverterconverter=newglobal::System.Text.Json.SourceGeneration.Tests.CustomConverterFactory();global::System.TypetypeToConvert=typeof(global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory);if(!converter.CanConvert(typeToConvert)){thrownewglobal::System.InvalidOperationException($"The converter '{converter.GetType()}' is not compatible with the type '{typeToConvert}'.");}elseif(converterisglobal::System.Text.Json.Serialization.JsonConverterFactoryfactory){global::System.Text.Json.Serialization.JsonConverter?actualConverter=factory.CreateConverter(typeToConvert,Options);if(actualConverter==null||actualConverterisglobal::System.Text.Json.Serialization.JsonConverterFactory){thrownewglobal::System.InvalidOperationException($"JsonConverterFactory '{factory.GetType()}' cannot return a 'null' or 'JsonConverterFactory' value.");}converter=actualConverter;}_ClassWithCustomConverterFactory=global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Text.Json.SourceGeneration.Tests.ClassWithCustomConverterFactory>(Options,converter);}}return_ClassWithCustomConverterFactory;}}}}

Author:	steveharter
Assignees:	steveharter
Labels:	area-System.Text.Json
Milestone:	6.0.0

[eiriktsarpalis]

Not relevant to the scope of this PR, but here is another instance of non-localized error messages: #58292.

[steveharter]

Since this is a run-time exception, not design-time, I think it should remain non-localized.

[eiriktsarpalis]

Looks good, but would it be possible to incorporate a fix for converter factories specified on the property level? See #58267 (comment) on the original issue.

[eiriktsarpalis]

Where does this branch type test for converter factories?

[steveharter]

It doesn't... The code before that that is shared between value types and reference types will call GetConverterFromFactory() for factories.

Also the error check for CanConvert was pre-existing from this PR. It applies to factory and non-factory cases although it may not be necessary for the factory case, as I'm not sure we double-check this in the serializer case (i.e. I don't think we verify the result from factory.CreateConverter()).

[eiriktsarpalis]

Thanks, I was looking for this logic in the Emitter.cs diff. I know this predates your PR, but shouldn't this method live in Emitter.cs?

[eiriktsarpalis]

Ah, I'm assuming it's because we're embedding the generated initialization expression as a field in the property generation spec.

[steveharter]

Yes the parser:emitter abstraction is broken here.

[layomia]

Ideally it should be moved to the emitter, perhaps in a later PR.

[steveharter]

/backport to release/6.0

[github-actions]

Started backporting to release/6.0: https://github.com/dotnet/runtime/actions/runs/1199230405