How do I reflect a dotnet web api endpoint that uses query string parameters in SwagggerUI?

Question

I'm trying to implement a dotnet web api with API versioning that uses query strings and headers. Here im using swagger to document and test the endpoints. I successfully used path versioning and reflected the endpoints in swagger. But im struggling to understand how to reflect query string & header versioning in swagger. I tried to find a solution from this article https://swagger.io/docs/specification/describing-parameters/#query-parameters but was still confused how to implement this in my dotnet web api.

My project contains 2 main controller classes with the following API versions.

1. WeatherForecastController.cs

    namespace QueryStringVersioning.Controllers
    {
    [ApiController]
    [ApiVersion("1.0")]
    [ApiVersion("1.1", Deprecated = true)]
    [ApiVersion("3.0")]
    [Route ("api")] //support query string & header versioning
    // [Route("api/v{version:apiVersion}/[controller]")] //support path versioning 
    public class WeatherForecastController : ControllerBase
    {
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", 
    "Scorching"
    };
   
    private readonly ILogger<WeatherForecastController> _logger;
   
    public WeatherForecastController(ILogger<WeatherForecastController> logger)
    {
        _logger = logger;
    }
   
    [HttpGet]
    public IEnumerable<WeatherForecast> Get()
    {
        var rng = new Random();
        return Enumerable.Range(1, 5).Select(index => new WeatherForecast
        {
            Date = DateTime.Now.AddDays(index),
            TemperatureC = rng.Next(-20, 55),
            Summary = Summaries[rng.Next(Summaries.Length)]
        })
        .ToArray();
    }
   
   
    [HttpGet, MapToApiVersion("3.0")]
    public IActionResult GetV3_0() => Ok(new string[] { "MapToApiVersion value 3.0" });
   
    [HttpGet, MapToApiVersion("1.1")]
    public IActionResult GetV1_1() => Ok(new string[] { "Depreceated MapToApiVersion value" });
    }}
   

2. WeatherForecastController2.cs

    namespace QueryStringVersioning.Controllers2
    {
    [ApiController]
    [ApiVersion("2.0")]
    [ApiVersion("2.1")]
    [Route ("api")] //support query string & header versioning
    // [Route("api/v{version:apiVersion}/[controller]")] //support path versioning 
    public class WeatherForecastController : ControllerBase
    {
    public IActionResult GetV2_0() => Ok(new string[] { "This is API Version 2.0" });
   
    [HttpGet, MapToApiVersion("2.1")]
    public IActionResult GetV2_1() => Ok(new string[] { "This is API Version 2.1" });
    }}
   

And the startup.cs file

    namespace QueryStringVersioning
    {
    public class Startup
    {
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSwaggerGen(c =>
        {

            c.SwaggerDoc("v1", new Microsoft.OpenApi.Models.OpenApiInfo
            {
                Version = "v1",
                Title = "API_Versioning V1",
            });

            c.SwaggerDoc("v1.1", new Microsoft.OpenApi.Models.OpenApiInfo
            {
                Version = "v1.1",
                Title = "API_Versioning V1.1",
                
            });

            c.SwaggerDoc("v2", new Microsoft.OpenApi.Models.OpenApiInfo
            {
                Version = "v2",
                Title = "API_Versioning V2"
            });

            c.SwaggerDoc("v2.1", new Microsoft.OpenApi.Models.OpenApiInfo
            {
                Version = "v2.1",
                Title = "API_Versioning V2.1"
            });

            c.SwaggerDoc("v3", new Microsoft.OpenApi.Models.OpenApiInfo
            {
                Version = "v3",
                Title = "API_Versioning V3"
            });
            
            c.ResolveConflictingActions (apiDescriptions => apiDescriptions.First ());
            // c.OperationFilter<RemoveVersionFromParameter>();
            // c.DocumentFilter<ReplaceVersionWithExactValueInPath>();
             
            
                    
        });
        services.AddControllers();
        services.AddMvc();
        services.AddApiVersioning(option =>
        {
            option.ReportApiVersions = true;
            option.AssumeDefaultVersionWhenUnspecified = true;
            option.DefaultApiVersion = new ApiVersion(1, 0);
            // Supporting multiple versioning scheme
            option.ApiVersionReader = ApiVersionReader.Combine(new HeaderApiVersionReader("X-version"), new QueryStringApiVersionReader("api-version"));
            
        });

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseHttpsRedirection();

        app.UseRouting();

        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });

        // Enable middleware to serve generated Swagger as a JSON endpoint.
        app.UseSwagger();
        // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
        // specifying the Swagger JSON endpoint.
        app.UseSwaggerUI(c =>
        {
            c.SwaggerEndpoint("/swagger/v1/swagger.json", "API_Versioning V1.0");
            c.SwaggerEndpoint("/swagger/v1.1/swagger.json", "API_Versioning V1.1");
            c.SwaggerEndpoint("/swagger/v2/swagger.json", "API_Versioning V2.0");
            c.SwaggerEndpoint("/swagger/v2.1/swagger.json", "API_Versioning V2.1");
            c.SwaggerEndpoint("/swagger/v3/swagger.json", "API_Versioning V3.0");
        });
        }
        }
        }

Answer 1

@michael-wang is correct. You need to also include the API Versioning API Explorer extensions. This extensions make API discovery API version aware. One of the many possible uses for this information is OpenAPI/Swagger integration.

Links to all of the applicable NuGet packages are listed on the API Versioning landing page. There is also an end-to-end example provided using Swashbuckle.