FileResponse does not generate required Produces value in swagger.json

[izzycoding]

I have an API action that returns a PhysicalFileResponse. But no matter what I do I cannot get the output swagger.json to contain the correct definition.

As I understand it there should be a type of "file" and something to do with "byte" in there, but all I get is:
...consumes:[],produces[],...

This means when I try to generate a Client using NSwag it creates code that either returns nothing (or if I use [Produces(typeof(PhysicalFileResponse))] then it does not handle the response as a file.

Am I doing something wrong or is this a missing feature?

[domaindrivendev]

In this scenario, it's difficult for Swashbuckle to do the right thing because ASP.NET Core's built-in metatdata provider - ApiExplorer doesn't provide enough information.

The good news is that someone has already posted an issue to the Mvc repo for this. It's well worth a read because the thread includes a decent workaround that you can use:

aspnet/Mvc#5701.

It sounds like there might be changes to ApiEXplorer coming soon that will help but until then, I'm going to move this issue to the backlog.

[domaindrivendev]

See #1034 for a working approach to describing operations that return a file.