API Documentation

Adding documentation is often the final, pivotal step in making your versioned services available to clients and fosters their utilization. While there are many approaches to documenting your services, OpenAPI (formerly Swagger) has quickly become the de facto method for describing REST services.

The ASP.NET API versioning project provides several new API explorer implementations that make it easy to add versioning into your OpenAPI configurations. Each of these API explorers do all of the heavy lifting to discover and collate your REST services by API version. They do not directly rely on nor use any external OpenAPI libraries so that you can use them for other scenarios as well.

Any OpenAPI generator such as NSwag or Swashbuckle that uses the API Explorer can be used; however, most examples use Swashbuckle for historical reasons.

ASP.NET Web API

Everything you need to add versioned documentation to your API controllers.

config.AddApiVersioning();

// format the version as "'v'major[.minor][-status]"
var apiExplorer = config.AddVersionedApiExplorer( o => o.GroupNameFormat = "'v'VVV" );

config.EnableSwagger(
    "{apiVersion}/swagger",
    swagger =>
    {
        swagger.MultipleApiVersions(
            ( apiDescription, version ) => apiDescription.GetGroupName() == version,
            info =>
            {
                foreach ( var group in apiExplorer.ApiDescriptions )
                {
                    info.Version( group.Name, $"Example API {group.ApiVersion}" );
                }
            } );
    } )
 .EnableSwaggerUi( swagger => swagger.EnableDiscoveryUrlSelector() );

Review the example project for additional setup and configuration options.

ASP.NET Web API with OData

Everything you need to add versioned documentation to your OData controllers.

configuration.AddApiVersioning();

var modelBuilder = new VersionedODataModelBuilder( configuration )
{
    ModelConfigurations = { new MyModelConfiguration() }
};

configuration.MapVersionedODataRoutes( "odata", "api", modelBuilder );

// format the version as "'v'major[.minor][-status]"
var apiExplorer = configuration.AddODataApiExplorer( o => o.GroupNameFormat = "'v'VVV" );

configuration.EnableSwagger(
    "{apiVersion}/swagger",
    swagger =>
    {
        swagger.MultipleApiVersions(
            ( apiDescription, version ) => apiDescription.GetGroupName() == version,
            info =>
            {
                foreach ( var group in apiExplorer.ApiDescriptions )
                {
                    info.Version( group.Name, $"Example API {group.ApiVersion}" );
                }
            } );
    } )
 .EnableSwaggerUi( swagger => swagger.EnableDiscoveryUrlSelector() );

Review the following example projects for additional setup and configuration options:

• OData OpenAPI Example
• Partial OData OpenAPI Example

Note: This API explorer does not directly tie into Swashbuckle with OData because that project also prescribes how API versioning is performed, which is incompatible with this project.

ASP.NET Core

Everything you need to add versioned documentation to your Minimal and controller-based APIs.

public class ConfigureSwaggerOptions : IConfigureOptions<SwaggerGenOptions>
{
  readonly IApiVersionDescriptionProvider provider;

  public ConfigureSwaggerOptions( IApiVersionDescriptionProvider provider ) =>
    this.provider = provider;

  public void Configure( SwaggerGenOptions options )
  {
    foreach ( var description in provider.ApiVersionDescriptions )
    {
      options.SwaggerDoc(
        description.GroupName,
          new OpenApiInfo()
          {
            Title = $"Example API {description.ApiVersion}",
            Version = description.ApiVersion.ToString(),
          } );
    }
  }
}

var builder = WebApplication.CreateBuilder( args );

builder.Services.AddControllers();
builder.Services.AddProblemDetails();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddApiVersioning()
                .AddMvc() // ← bring in MVC (Core); not required for Minimal APIs
                .AddApiExplorer(
                     // format the version as "'v'major[.minor][-status]"
                     options => options.GroupNameFormat = "'v'VVV" );

services.AddTransient<IConfigureOptions<SwaggerGenOptions>, ConfigureSwaggerOptions>();
services.AddSwaggerGen();

var app = builder.Build();

app.UseSwagger();
app.UseSwaggerUI(
    options =>
    {
        foreach ( var description in app.DescribeApiVersions() )
        {
            var url = $"/swagger/{description.GroupName}/swagger.json";
            var name = description.GroupName.ToUpperInvariant();
            options.SwaggerEndpoint( url, name );
        }
    } );
app.MapControllers();
app.Run();

Review the following example projects for additional setup and configuration options:

• OpenAPI Example
• Minimal OpenAPI Example

ASP.NET Core with OData

Everything you need to add versioned documentation to your OData controllers.

public class ConfigureSwaggerOptions : IConfigureOptions<SwaggerGenOptions>
{
  readonly IApiVersionDescriptionProvider provider;

  public ConfigureSwaggerOptions( IApiVersionDescriptionProvider provider ) =>
    this.provider = provider;

  public void Configure( SwaggerGenOptions options )
  {
    foreach ( var description in provider.ApiVersionDescriptions )
    {
      options.SwaggerDoc(
        description.GroupName,
          new OpenApiInfo()
          {
            Title = $"Example API {description.ApiVersion}",
            Version = description.ApiVersion.ToString(),
          } );
    }
  }
}

var builder = WebApplication.CreateBuilder( args );

builder.Services.AddControllers().AddOData();
builder.Services.AddProblemDetails();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddApiVersioning()
                .AddOData( options => options.AddRouteComponents() )
                .AddODataApiExplorer(
                     // format the version as "'v'major[.minor][-status]"
                     options => options.GroupNameFormat = "'v'VVV" );

services.AddTransient<IConfigureOptions<SwaggerGenOptions>, ConfigureSwaggerOptions>();
services.AddSwaggerGen();

var app = builder.Build();

app.UseSwagger();
app.UseSwaggerUI(
    options =>
    {
        foreach ( var description in app.DescribeApiVersions() )
        {
            var url = $"/swagger/{description.GroupName}/swagger.json";
            var name = description.GroupName.ToUpperInvariant();
            options.SwaggerEndpoint( url, name );
        }
    } );
app.MapControllers();
app.Run();

Review the following example projects for additional setup and configuration options:

• OData OpenAPI Example
• Partial OData OpenAPI Example