Different StringEnumConverter-Behavior between STJ / Newtonsoft

[angelaki]

Switching my project from Newtonsoft to STJ, I noticed the following different behavior between the two scheme generators:

Adding the JsonStringEnumConverter makes Swashbuckle aware of enums being serialized as string - so far, so good. But the STJ schema builder doesn't seam to be aware of IDictionary<[Enum], int>.

For Newtonsoft the following scheme was generated:

...
"properties": {
  "EnumValue1": {
	"type": "integer",
	"format": "int32"
  },
  "EnumValue2": {
	"type": "integer",
	"format": "int32"
  },
  "EnumValue3": {
	"type": "integer",
	"format": "int32"
  }
},
"additionalProperties": false,
...

Now I only get

"additionalProperties": {
  "type": "integer",
  "format": "int32"
},

So it's still being recognized as an object containing integer properties. Better than nothing. But the old scheme was way more explicit.

[martincostello]

This might be related to dotnet/runtime#47765 and this comment:

Swashbuckle.AspNetCore/src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/JsonSerializerDataContractResolver.cs

Lines 60 to 67 in a17b464

	if (IsSupportedDictionary(type, out Type keyType, out Type valueType))
	{
	return DataContract.ForDictionary(
	underlyingType: type,
	valueType: valueType,
	keys: null, // STJ doesn't currently support dictionaries with enum key types
	jsonConverter: JsonConverterFunc);
	}

It's possible this is fixed by #2799, otherwise we might have to see if there's any changes needed to if the assertion in that comment is no longer true.

[martincostello]

You may have to opt-in to this behaviour with JsonSerializerOptions.DictionaryKeyPolicy.

[angelaki]

Thank you so much for checking! Butt sorry, not quite sure what you mean? I've set options.JsonSerializerOptions.DictionaryKeyPolicy = System.Text.Json.JsonNamingPolicy.CamelCase; for testing purposes now but no difference on the output.

The serializer itself works (using .Net 8.0, but also checked 7 & 6), generating strings for the keys.

[angelaki]

I could sure support here with a PR :) Can you give me a hint where to start?

[martincostello]

I'm not sure where specifically without starting to debug it myself.