Odata is not compatible with AddOpenApi of Microsoft.AspNetCore.OpenApi

[Angelinsky7]

Assemblies affected
Microsoft.AspNetCore.OpenApi: 9.0.0
Microsoft.AspNetCore.OData: 9.1.1

Describe the bug
To be able to use AddOpenApi and MapOpenApi the controllers need to have a ApiControllerAttribute but Odata documentation ask use to remove it. The controller is then not found inside the openApi document.
The actual snippet of code to add openApiDocument create another document instead of adding the routes inside the already created document.
I would like to have only one openApi document and a usable openapi.json file.

Is there a workaround to be able to use ApiController and OData (without removing all routing conventions or have duplicate actions ? )

Thanks !

[julealgon]

the controllers need to have a ApiControllerAttribute but Odata documentation ask use to remove it.

@Angelinsky7 would you mind sharing a link to where that recommendation is made? That sounds like bad advice to me. I assume it is linked to the requirement that [ApiController] requires attribute routing, whereas OData doesn't.

Yet another reason to consider deprecating routing conventions in OData (IMHO).

[Angelinsky7]

@julealgon thanks for your answer...

here you can find it : https://github.com/OData/AspNetCoreOData/blob/main/docs/routing-pitfalls.md

the thing is that to make odata works correctly the only solution that i have found is to EXACTLY do the incorrect code...

some code for those you are interested to try to make this work correctly

Program.cs

builder.Services.AddControllersWithViews()
    .AddApplicationPart(typeof(_ApiAssembly).Assembly)
    .AddControllersAsServices()
    .AddOData(options => {
        options.EnableAttributeRouting = true;
        options.TimeZone = TimeZoneInfo.Utc;
        options.EnableQueryFeatures();
        options.RouteOptions.EnableNonParenthesisForEmptyParameterFunction = true;
        options.RouteOptions.EnableActionNameCaseInsensitive = true;
        options.RouteOptions.EnableControllerNameCaseInsensitive = true;
        options.RouteOptions.EnablePropertyNameCaseInsensitive = true;
        options.RouteOptions.EnableKeyAsSegment = true;
        options.RouteOptions.EnableKeyInParenthesis = false;
        options.AddRouteComponents(routePrefix: "api", model: modelBuilder.GetEdmModel(), configureServices: services => {
            //services.AddSingleton<IFilterBinder, CustomFilterBinder>();
            services.AddOdataLinkProvider(typeof(_ApiAssembly).Assembly);
            services.AddSingleton<IODataSerializerProvider, CustomODataSerializerProvider>();
        });
    })
    .AddJsonOptions(options => {
        options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
        options.JsonSerializerOptions.DictionaryKeyPolicy = JsonNamingPolicy.CamelCase;
        options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
    });

builder.Services.AddOpenApi();

ModelBuilder

EntitySetConfiguration<Thing> entitySet = modelBuilder.EntitySet<Thing>("things");
EntityTypeConfiguration<Thing> entityType = entitySet .EntityType;
entityType .HasKey(p => p.Id);

Controller

using System.Net;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.OData.Query;
using Microsoft.AspNetCore.OData.Results;
using Microsoft.AspNetCore.OData.Routing.Controllers;
using Microsoft.EntityFrameworkCore;

namespace Controllers {

    [ApiController]
    [Route("/api/things")]
    public class ThingsController : ODataController {

        [HttpGet]
        [EnableQuery]
        [ProducesResponseType(typeof(PageResult<Thing>), statusCode: (Int32)HttpStatusCode.OK)]
        public async Task<ActionResult<IAsyncEnumerable<Thing>>> Get(CancellationToken cancellationToken = default) {}

        [HttpGet("{key}")]
        [EnableQuery]
        [ProducesResponseType(typeof(SingleResult<Thing>), statusCode: (Int32)HttpStatusCode.OK)]
        [ProducesResponseType(typeof(ProblemDetails), statusCode: (Int32)HttpStatusCode.NotFound)]
        [ProducesResponseType((Int32)HttpStatusCode.BadRequest)]
        [ProducesResponseType((Int32)HttpStatusCode.InternalServerError)]
        public async Task<IActionResult> GetById([FromRoute] Int64 key, CancellationToken cancellationToken = default) {}

        [HttpPost]
        [ProducesResponseType(typeof(CreatedAtActionResult), statusCode: (Int32)HttpStatusCode.OK)]
        [ProducesResponseType(typeof(ProblemDetails), statusCode: (Int32)HttpStatusCode.NotFound)]
        [ProducesResponseType((Int32)HttpStatusCode.BadRequest)]
        [ProducesResponseType((Int32)HttpStatusCode.InternalServerError)]
        public async Task<IActionResult> Post([FromBody] ThingCreateRequest request, CancellationToken cancellationToken = default) {}

        [HttpPut("{key}")]
        [ProducesResponseType((Int32)HttpStatusCode.NoContent)]
        [ProducesResponseType(typeof(ProblemDetails), statusCode: (Int32)HttpStatusCode.NotFound)]
        [ProducesResponseType((Int32)HttpStatusCode.BadRequest)]
        [ProducesResponseType((Int32)HttpStatusCode.InternalServerError)]
        public async Task<IActionResult> Put([FromRoute] Int64 key, [FromBody] ThingUpdateRequest request, CancellationToken cancellationToken = default) {}

        [HttpDelete("{key}")]
        [ProducesResponseType((Int32)HttpStatusCode.NoContent)]
        [ProducesResponseType(typeof(ProblemDetails), statusCode: (Int32)HttpStatusCode.NotFound)]
        [ProducesResponseType((Int32)HttpStatusCode.BadRequest)]
        [ProducesResponseType((Int32)HttpStatusCode.InternalServerError)]
        public async Task<IActionResult> Delete([FromRoute] Int64 key, CancellationToken cancellationToken = default) {}

    }
}

Model

namespace Models {

    public class Thing {

        public Int64 Id { get; set; } = default!;

        public required String Name { get; set; }

    }
}

With all of this... everything is working... in $odata i have everything in duplicate but it's working correctly.

[julealgon]

in $odata i have everything in duplicate but it's working correctly.

Yep.... this is a known problem:

• Duplicate results shown in OData route debug view for conventional and attribute routed routes #428

You can work around it by either making sure your methods don't match the built-in conventions (super cryptic approach, wouldn't recommend), or by disabling the OData route conventions (also not great as there is no "simple" API to do that, but is usually what I'd suggest).

The only other comments I'd add based on your example @Angelinsky7 is that you can use API conventions to simplify some of that nasty [Produces...] boilerplate if you have many controllers.

• ASP.NET Core - Use web API conventions

And I would strongly recommend leveraging ActionResult<T> instead of IActionResult as that provides stronger types and can help with some OData-specific issues where returning IActionResult causes it to not match the EDM model due to lack of typing information. ActionResult<T> has an added bonus in that if you provide a concrete type there, you don't need to specify the success return type using [ProducesResponseType]: it is picked up automatically.

[Angelinsky7]

thanks i didn't know the api conventions things... and will do the stronger types for ActionResult...
i'll be waiting for #428 to be resolved.
maybe we could have a better (or a complete) documentation about the "correct" config ?!