APIs: Use EndpointMetadata to check for MapToApiAttribute at runtime to include Controller in Swagger document

[mdubbelv]

Prerequisites

This PR fixes this issue:
#20143

It adds the possibility to add Controllers to a Swagger document at runtime. For example by using a IApplicationModelConvention
That is achieved by not checking MethodInfo and instead checking ActionDescriptor.EndpointMetaData when trying to find a MapToApiAttribute on a Controller when filtering out documents using SwaggerGenOptions.DocInclusionPredicate.

Description

Test by:

1. Add custom Swagger document
2. Add Controller with MapToApiAttribute matching the custom Swagger document
   See more: https://docs.umbraco.com/umbraco-cms/reference/api-versioning-and-openapi#adding-your-own-swagger-documents

[github-actions]

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[Questo]

looking at other files in the source code, the pattern appears to not be using primary constructors without private backing fields. so maybe revert this change to again use private backing fields instead to adhere to the style guide set

[mdubbelv]

Might be time to migrate over to primary constructors while editing a class. Maybe we'll let a main contributor have his/her/their say.

[AndyButland]

Yes, I think let's revert this back please - just so we are consistent throughout the code base and don't present something that might be a bit surprising still to a contributor.

[AndyButland]

Thanks for raising this issue @mdubbelv-consid and providing a solution. I've tested out, and it looks to work as expected.

Let me just relay my testing steps so you or anyone else looking at this can verify they are valid.

1. Created a new, standalone management API endpoint:

using Asp.Versioning;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Umbraco.Cms.Api.Common.Attributes;
using Umbraco.Cms.Api.Common.Filters;
using Umbraco.Cms.Api.Common.ViewModels.Pagination;
using Umbraco.Cms.Api.Management.DependencyInjection;
using Umbraco.Cms.Api.Management.Filters;
using Umbraco.Cms.Api.Management.Routing;
using Umbraco.Cms.Api.Management.ViewModels.Culture;
using Umbraco.Cms.Core;
using Umbraco.Cms.Web.Common.Authorization;
using Umbraco.Cms.Web.Common.Filters;

namespace Umbraco.Cms.Api.Management.Controllers.Culture;

[ApiVersion("1.0")]
[VersionedApiBackOfficeRoute("andy-testing")]
[ApiExplorerSettings(GroupName = "Andy Testing")]
[ApiController]
[Authorize(Policy = AuthorizationPolicies.BackOfficeAccess)]
[MapToApi(ManagementApiConfiguration.ApiName)]
[JsonOptionsName(Constants.JsonOptionsNames.BackOffice)]
[AppendEventMessages]
[DisableBrowserCache]
public class TestController : Controller
{
    [HttpGet]
    [MapToApiVersion("1.0")]
    [ProducesResponseType(typeof(PagedViewModel<CultureReponseModel>), StatusCodes.Status200OK)]
    public Task<string> Get(CancellationToken cancellationToken)
    {
        return Task.FromResult("Hello");
    }
}

2. Verified that it appeared on the Swagger UI at: /umbraco/swagger/index.html?urls.primaryName=Umbraco+Management+API

3. Commented out [MapToApi(ManagementApiConfiguration.ApiName)] and verified that it no longer appeared.

4. Add the following class to the solution:

using Microsoft.AspNetCore.Mvc.ApplicationModels;
using Umbraco.Cms.Api.Common.Attributes;
using Umbraco.Cms.Api.Management.Controllers.Culture;

namespace Umbraco.Cms.Api.Management;

public sealed class MapToApiConvention(string apiName) : IApplicationModelConvention
{
    public void Apply(ApplicationModel app)
    {
        SetMapToApiName(app, apiName);
    }

    private static void SetMapToApiName(ApplicationModel app, string apiName)
    {
        foreach (var controller in app.Controllers)
        {
            if (!typeof(TestController).IsAssignableFrom(controller.ControllerType))
                continue;

            if (controller.Attributes.OfType<MapToApiAttribute>().Any())
                continue;

            var attribute = new MapToApiAttribute(apiName);

            foreach (var action in controller.Actions)
            {
                foreach (var selector in action.Selectors)
                {
                    selector.EndpointMetadata.Add(attribute);
                }
            }
        }
    }
}

5. Registered it in my start-up project with:

  public void Compose(IUmbracoBuilder builder) => builder.Services
      .AddMvc(options =>
      {
          options.Conventions.Add(new MapToApiConvention("management"));
      });

6. Verified that with the current code in main the endpoint still does not appear on the Swagger UI documentation.
7. Switched to the code provided by this PR, rebuilt, and now the endpoint does appear on the Swagger UI documentation.

So I think this is all good to go once the raised comments are resolved.

I'll also ask - but not insist as I don't know how difficult it would be - but wonder if it's possible to add some form of automated testing for this? I.e. verify that ConfigureUmbracoSwaggerGenOptions will now correctly handle both compile and runtime attributes. That would be nice as a check against future regressions and also help document the behaviour.

[AndyButland]

Yes, I think let's revert this back please - just so we are consistent throughout the code base and don't present something that might be a bit surprising still to a contributor.

[AndyButland]

Could you add some XML header comments on this public class and the public methods within please? Just so it's clear for anyone coming across this in future what's it's doing and what problem it's solving.