API versioning in Swagger UI

Question

I'm looking into .net core 6, API versioning and trying to show two versions "v1" and "v2" in swagger UI but only "v1" is showing though no error is appearing.

Here is my program.cs code

   builder.Services.AddApiVersioning(setup =>
    {
        setup.DefaultApiVersion = new ApiVersion(1,0);
        setup.AssumeDefaultVersionWhenUnspecified = true;
        setup.ReportApiVersions = true;
    });

    builder.Services.AddVersionedApiExplorer(setup =>
    {
        setup.GroupNameFormat = "'v'VVV";
        setup.SubstituteApiVersionInUrl = true;
    });

    builder.Services.AddSwaggerGen(options =>
    {
        
        options.SwaggerDoc("v1", new OpenApiInfo
        {
            Version = "v1",
            Title = "API",
            Description = "An API in dotnet core 6",

        });
        var xmlFilename = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
        options.IncludeXmlComments(Path.Combine($@"{AppContext.BaseDirectory}", xmlFilename));
    });

    if (app.Environment.IsDevelopment())
    {
        app.UseSwagger();
        app.UseSwaggerUI();
    }

v1 controller have this action method

    [MapToApiVersion("1.0")]
    [HttpGet]
    [Route("GetLast12MonthBalances")]
    public async Task<ApiResponse> GetLast12MonthBalances()
    {

v2 controller have this action method

   [MapToApiVersion("2.0")]
   [HttpGet,Route("GetLast12MonthBalances")]
   public async Task<ApiResponse> GetLast12MonthBalances()
   {

Any idea what is missing?

Answer 1

You need to configure SwaggerGenOptions using options pattern.

1st- Create a class as follows:

namespace MyApi
{
    public class ConfigureSwaggerOptions
        : IConfigureNamedOptions<SwaggerGenOptions>
    {
        private readonly IApiVersionDescriptionProvider provider;

        public ConfigureSwaggerOptions(
            IApiVersionDescriptionProvider provider)
        {
            this.provider = provider;
        }

        public void Configure(SwaggerGenOptions options)
        {
            // add swagger document for every API version discovered
            foreach (var description in provider.ApiVersionDescriptions)
            {
                options.SwaggerDoc(
                    description.GroupName, 
                    CreateVersionInfo(description));
            }
        }

        public void Configure(string name, SwaggerGenOptions options)
        {
            Configure(options);
        }

        private OpenApiInfo CreateVersionInfo(
                ApiVersionDescription description)
        {
            var info = new OpenApiInfo()
            {
                Title = "My API",
                Version = description.ApiVersion.ToString()
            };

            if (description.IsDeprecated)
            {
                info.Description += " deprecated API.";
            }

            return info;
        }
    }
}

2-wire up the options with the service collection

public void ConfigureServices(IServiceCollection services)
{
    services.AddScoped<ITestsRepository, TestssRepository>();
    services.AddControllers();

    services.AddApiVersioning(setup =>
    {
        setup.DefaultApiVersion = new ApiVersion(1, 0);
        setup.AssumeDefaultVersionWhenUnspecified = true;
        setup.ReportApiVersions = true;
    });

    services.AddVersionedApiExplorer(setup =>
    {
        setup.GroupNameFormat = "'v'VVV";
        setup.SubstituteApiVersionInUrl = true;
    });

    services.AddSwaggerGen();
    services.ConfigureOptions<ConfigureSwaggerOptions>();
}