Type match incorrect for PATCH requests

[bjornharrtell]

It seems logic is at fault at:

JsonApiDotNetCore/src/JsonApiDotNetCore/Middleware/DefaultTypeMatchFilter.cs

Lines 33 to 34 in 36bc489

	var deserializedType = context.ActionArguments.FirstOrDefault().Value?.GetType();
	var targetType = context.ActionDescriptor.Parameters.FirstOrDefault()?.ParameterType;

For PATCH requests that will compare the path id parameter not the entity.

[bjornharrtell]

LastOrDefault could possible be more logical but not sure it it's foolproof.

[bart-degreed]

Hi @bjornharrtell, I'm not confident I understand what is going on here exactly. Can you write up a test that demonstrates the problem?

[maurei]

Closing due to inactivity. I tried reproducing a bug but I haven't been able to. Feel free to reply with new information and we'll check it out.

[bart-degreed]

Reopening, as I can reproduce the problem.
Both lines pick the first argument, while the info we need is at the second argument for both lines.

Debug the test Can_Update_ToMany_Relationship_By_Patching_Resource and add a breakpoint on these lines.
It is comparing Guid types, while it should be comparing TodoItemCollection types.

[bart-degreed]

OrDefault().Value is wrong anyway, it would immediately crash in case of default.

[bjornharrtell]

@bart-degreed I can confirm that your observations are the same as mine.

[maurei]

Thanks for looking into this. I realise I was looking completely in the wrong direction for a reproduction.

LastOrDefault could possible be more logical but not sure it it's foolproof.

This is correct, but just Last, default values make no sense here. It does actually. The default value is a [null, null] key value pair, which happens for example when an empty relationship collection is patched to a ../relationships/.. endpoint

We also need to move away from inspecting ActionDescriptor parameters because this will lead to a comparison with Object type for the {id}/relationships/{relationshipName} endpoint, which will never match the runtime type in ActionArguments. See endpoint method signature.

We can resolve the expected type from IJsonApiRequest instead