Filtering schema out of NSwag swagger - asp.net-web-api

Question

I have an ASP.NET full framework application with API endpoints. I am using NSwag to generate a swagger document. This all works.
I need to generate a document for only a small subset of the endpoints. The paths are filtered, but the schema is not. How do I filter the schema objects to match the path filtering?
Example:
I have this filter
public class IncludeControllersInSwagger : IOperationProcessor
{
public Task<bool> ProcessAsync(OperationProcessorContext context)
{
return Task.FromResult(
context.ControllerType == typeof(ControllerA));
}
}
And this at startup:
settings.GeneratorSettings.OperationProcessors.Add(new IncludeControllersInSwagger());
The controllers are:
public class AResponse
{
public string Message { get; set; }
public bool Flag { get; set; }
}
public class BResponse
{
public string Message { get; set; }
public int Count { get; set; }
}
[Route("a")]
public class ControllerA : ApiController
{
[HttpGet]
public AResponse Get()
{
return new AResponse
{
Message = "Hello from A",
Flag = true
};
}
}
[Route("b")]
public class ControllerB : ApiController
{
[HttpGet]
public BResponse Get()
{
return new BResponse
{
Message = "Hello from B",
Count = 42
};
}
}
Then the generated swagger contains just one path:
"paths": {
"/a": {
"get": { .. etc
}
}
And that's all, this is correct.
But the schemas contains both:
"schemas": {
"AResponse": {
"type": "object",
"additionalProperties": false,
etc
},
"BResponse": {
"type": "object",
"additionalProperties": false,
etc
}
}
}
The BResponse type should not be there. How do you remove it?
This extra data makes the Schemas section extremely verbose and unsuitable for public documentation in the case where there are over 10 endpoints, and only 2 are exposed via a gateway and therefor documented in swagger.
There is a ISchemaProcessor but it does not return a Boolean like the IOperationProcessor.

Answer 1

Have you tried to add the operation filter as first element?
i.e. OperationProcessors.Insert(0, new IncludeControllersInSwagger())
I think this is important as it will filter out the operation before the dto schemas are generated and added to the document.

Answer 2

This is not an answer to your problem, as you already got an answer that seems to work. I do have a suggestion however. Instead of checking the type of controller in your processor, I would suggest to create a custom attribute:
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class)]
public class IncludeInSwaggerAttribute : Attribute
{
}
Then change your processor to look for this attribute:
public class IncludeInSwaggerOperationProcessor : IOperationProcessor
{
public async Task<bool> ProcessAsync(OperationProcessorContext context)
{
return context.ControllerType.GetCustomAttributes<IncludeInSwaggerAttribute>().Any() ||
context.MethodInfo.GetCustomAttributes<IncludeInSwaggerAttribute>().Any();
}
}
This way, you can add the attribute to any new controller you want to include in swagger without having to change your processor. You can also add the attribute on a single action to only include that action, leaving the rest of the actions in the controller out of swagger.