S.T.J.JsonSerializer does not serialize value tuples

[mazhou-msft]

Using latest nightly build of .NET Core 3.0 and write:

string s = JsonSerializer.ToString((a: 1, b: 2));
Console.WriteLine(s);

You will get a string representing an empty object {}. I think the right behavior is to have { "Item1": 1, "Item2": 2 } and I expect it should also work for deserialization.

[YohDeadfall]

@ahsonkhan @karelz I would like to take it.

[karelz]

Great @YohDeadfall. I sent you collaborator invite to CoreFX repo. We recommend to swtich the repo to Not Watching, otherwise you will receive 500+ notifications per day (may be a bit overwhelming). The Not Watching setting will send you notifications for issues where you are mentioned, you are assigned or where you explicitly subscribed.
Once you accept the collaborator invite, please ping me, I will assign the issue to you then (GH limitation, assigning to myself for now).

[YohDeadfall]

By the way, can you replace "value tuples" in the title by "structures"?

[karelz]

Well, the original issue was for "value tuples". Do you mean it could / should be generalized? If yes, I let @ahsonkhan comment on that.

[mazhou-msft]

It does work for some of the primitive structures such as DateTime, however it does not work for DateTimeOffset. They could be different issues to track.

[YohDeadfall]

@mazhou-msft DateTimeOffset is a different kind of structure which should be serialized as a single value. Such kind of types should be handled by value converters. I'm talking about value types which have serializable public properties and fields.

@karelz Take a look at the expected output. There are Item1 and Item2 properties which corresponds to fields of ValueTuple<,>. So the issue isn't about serialization of value tuples with their field aliases which are a and b in the example.

[mazhou-msft]

Make sense.

For the expected result, I would say a and b may be more natural, but it makes things harder (for those runtime TupleElementName checks etc.) back one step, Item1 and Item2 are still acceptable results as they are identitical to what Json.NET returns for value tuples.

For the second issue regarding the DateTimeOffset, I expect at least get a JSON representing all public properties, if the value onverter is not ready yet; however I am receiving TargetInvocationException which seems a bug to me, we should fix it somewhere too.

[steveharter]

DateTimeOffset support was just added.

There is no converter yet for ValueTuple, so using this issue to track that.

[mazhou-msft]

Thanks for the info, sounds good.

[ahsonkhan]

Is this issue about providing struct support (i.e. value types), or is it about supporting ValueTuples specifically (which just happen to be a value type)?