.Net: FunctionResult serializer should use `JsonSerializerOptions.Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping`

[RamType0]

When I am using KernelFunction which returns user defined object, then it is called by Auto function invocation,
the result of the kernel function will be converted to string with JsonSerializer.Serialize via FunctionCallsProcessor.ProcessFunctionResult.

semantic-kernel/dotnet/src/InternalUtilities/connectors/AI/FunctionCalling/FunctionCallsProcessor.cs

Lines 479 to 494 in f8592ad

	public static string ProcessFunctionResult(object functionResult)
	{
	if (functionResult is string stringResult)
	{
	return stringResult;
	}
	// This is an optimization to use ChatMessageContent content directly
	// without unnecessary serialization of the whole message content class.
	if (functionResult is ChatMessageContent chatMessageContent)
	{
	return chatMessageContent.ToString();
	}
	return JsonSerializer.Serialize(functionResult);
	}

Because JsonSerializer.Serialize very likely to escape characters by default.
if I have this kind of record,

record A(string Text);

A a = new("ｵﾀﾞ ﾉﾌﾞﾅｶﾞ");

string x = JsonSerializer.Serialize(a);

the content of the x is ...

{"Text":"\uFF75\uFF80\uFF9E \uFF89\uFF8C\uFF9E\uFF85\uFF76\uFF9E"}

But at least, Azure OpenAI gpt-4o (2024-08-06) could not handle this kind of escaped characters.

But if I use

string y = JsonSerializer.Serialize(a, new JsonSerializerOptions(JsonSerializerOptions.Default)
{
    Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
});

The content of the y is ...

{"Text":"ｵﾀﾞ ﾉﾌﾞﾅｶﾞ"}

So it will be easily handled by LLM.

Thus, IMHO, FunctionCallsProcessor.ProcessFunctionResult should use new JsonSerializerOptions(JsonSerializerOptions.Default) { Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping, } for JsonSerializer.Serialize by default.

Also, even if we pass JsonSerializerOptions to IKernelBuilderPlugins AddFromType, it is not used for result serialization.

[moonbox3]

Hi @RamType0, thanks for filing the issue. The SK Java repo is housed here. Could you please re-file it in that repo? Thank you!

[RamType0]

No, it is .NET issue.
But the bot automatically added Java label.

[moonbox3]

Thanks for your response!

[sphenry]

@dmytrostruk can you take a look?