Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Conflicting method/path combination

Hi,

I have the following API controller with 2 GET actions

[Route("api/[controller]")]
[ApiController]
public class InvestorsController : ControllerBase
{
    [HttpGet("{id:guid}", Name = nameof(GetCrmInvestor))]
    public async Task<ActionResult<Dto.Crm.InvestorDto>> GetCrmInvestor(Guid id)
    {
    }

    [HttpGet("{id:int}", Name = nameof(GetCrowdInvestor))]
    public async Task<ActionResult<InvestorDto>> GetCrowdInvestor(int id)
    {
    }
}

I can successfully call both of these endpoints using Postman - 1 with an int, 1 with a guid - however, Swagger throws an exception:

Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Conflicting method/path combination "GET api/Investors/{id}" for actions - {full path to method}.GetCrmInvestor, {full path to method}.GetCrowdInvestor. Actions require a unique method/path combination for Swagger/OpenAPI 3.0. Use ConflictingActionsResolver as a workaround

This API is written in ASP.NET Core 5 (net5.0). Using Nuget package Swashbuckle.AspNetCore Version 6.0.7

This seems different to #1713 as I have provided a route name.

Am I doing something wrong?

[abdollahkahne]

@domaindrivendev What if we have this conflict regarding different API versions? For example I have this two methods which respond to /weatherforecast path according to specified api version but now swagger UI thrown the above exception.

  // Get /weatherforecast
        [Authorize]
        [HttpGet]
        [ProducesResponseType(200)]
        [MapToApiVersion("2.0")]
        public IEnumerable<WeatherForecast> Get()
        {
            return Get(3);
        }

         // Get /weatherforecast
        [Authorize]
        [HttpGet]
        [ProducesResponseType(200)]
        [MapToApiVersion("1.0")]
        public IEnumerable<WeatherForecast> GetV1()
        {
            return Get(5);
        }

       // Get /weatherforecast/7
        [Authorize]
        [HttpGet("{days:int}")]
        [ProducesResponseType(200)]
        public IEnumerable<WeatherForecast> Get(int days)
        {
            var rng = new Random();
            return Enumerable.Range(1, days).Select(index => new WeatherForecast
            {
                Date = DateTime.Now.AddDays(index),
                TemperatureC = rng.Next(-20, 55),
            })
            .ToArray();
        }

[domaindrivendev]

Swashbuckle is built on top of the OpenAPI Specification. That is, it generates an OpenAPI document that describes your API and then uses that document to power the swagger-ui.

In OpenAPI, each operation is uniquely identified by a combination a “path template” and a HTTP method. In this context, a “path template” is a relative path with curly braces (if applicable|) to mark a section of a URL path as replaceable using path parameter names. Similar to a “route template”, which is a concept internal to ASP.NET Core, but curly braces would only include parameter names, and not route constraint syntax.

With this in mind, your two operations would have the same “path template” (/investors/{id}) and the same HTTP method, and so the generated OpenAPI document would not be valid, hence the exception. To workaround this, you need to have something in the “path template” to distinguish them from eachother, and in this case it seems the parameter name is your best option because it wouldn’t change the API behavior in any way.

[Route("api/[controller]")]
[ApiController]
public class InvestorsController : ControllerBase
{
    [HttpGet("{guidId:guid}", Name = nameof(GetCrmInvestor))]
    public async Task<ActionResult<Dto.Crm.InvestorDto>> GetCrmInvestor(Guid guidId)
    {
    }

    [HttpGet("{intId:int}", Name = nameof(GetCrowdInvestor))]
    public async Task<ActionResult<InvestorDto>> GetCrowdInvestor(int intId)
    {
    }
}