Fix: OpenAPI attributes are not getting picked up if they are in a referenced class library project #298

[PanosKousidis]

This solution introduces an optional parameter to load referenced assemblies' types as well when trying to find out which methods are eligible to be shown on the SwaggerUI

[ghost]

All CLA requirements met.

[PanosKousidis]

There are 8 references of this function and I wasn't sure which ones needed to get the referenced types as well. I just changed the one that was causing the problem for me, perhaps more changes should be made and if they are more, we could potentially change the default value to true

[justinyoo]

@PanosKousidis Thanks for the PR! It could be really helpful. Do you mind providing a sample repo that causes the issue so that I can reproduce the same error on my end?

[PanosKousidis]

@justinyoo Here you are:
https://github.com/PanosKousidis/AzureFunctions.OpenAPI.Issue298

[justinyoo]

Thanks for the sample repo! I was able to reproduce the error.

I'll take a look + I'll take a further look, if we can also apply this approach to the in-proc worker.

[PanosKousidis]

Hi @justinyoo , I had a deeper look and it turns out that changing it to always include referenced types causes errors for 2 reasons:

1. The VisitorCollection.CreateInstance() method looks for types that end with "Visitor". If we load referenced assemblies this causes problems as other assemblies may have types that end with "Visitor" and are not compliant with the logic (e.g. they don't have parameterless constructors or any public constructors at all etc. Such is the case for a NewtonsoftJson package that is included in the referenced assemblies)
2. Loading referenced assemblies causes problems with the .SingleOrDefault(...) calls that expect for example one implementation of IOpenApiConfigurationOptions. By loading the referenced assemblies it loads the potential client function's implementation along with the referenced DefaultOpenApiConfigurationOptions and OpenApiSettings of your project.

To resolve (1) I changed the code in VisitorCollection.CreateInstance() to look for IVisitor interface implementations instead of classes ending in "Visitor", which should be ok, as the linq query has in its select statement (IVisitor)Activator.CreateInstance... so if it's not IVisitor there would be a problem anyway.

To resolve (2) I just excluded all types that belong in a namespace that starts with Microsoft.Azure.WebJobs.Extensions.OpenApi. That excludes all of your project so it works fine.

Now the GetLoadableTypes(...) can always include referenced assemblies and it seems to be working for me.
See comments on the commit above

[justinyoo]

I left a few comments. Would you please be able to take a look?

[PanosKousidis]

Yep, that's done

[justinyoo]

Thanks for the long wait! It looks good to me.