Defaulting to the Latest API Version on Swagger UI - asp.net-core

Question

I have implemented Swashbuckle.AspNetCore.SwaggerUI (version 6.1.4) in my API. The API also configures Microsoft.AspNetCore.Mvc.Versioning (version 5.0.0).
This is now working, and I can set the API version at the top of the page to resolve to the various exposed endpoints.
My question is, can I configure the Swagger UI to default the version drop-down list at the top-right of the Swagger page to the highest API version. Currently, this is displayed as follows:
Select a definition - V1.0 (default)
V1.1
V2.0
I would like the UI to default, in this case to the latest published version (V2.0)
Here is my code:
services.AddTransient<IConfigureOptions<SwaggerGenOptions>, SwaggerOptions>();
services.AddSwaggerGen(
options =>
{
options.EnableAnnotations();
var xmlCommentsPath = GetXmlCommentsFilePath();
if (File.Exists(xmlCommentsPath))
{
options.IncludeXmlComments(xmlCommentsPath);
}
options.AddSecurityDefinition(
"Bearer", new OpenApiSecurityScheme
{
Name = "Authorization",
Type = SecuritySchemeType.ApiKey,
Scheme = "Bearer",
BearerFormat = "JWT",
In = ParameterLocation.Header,
Description = "JWT Authorization header using the Bearer scheme."
});
options.AddSecurityRequirement(
new OpenApiSecurityRequirement
{
{
new OpenApiSecurityScheme
{
Reference = new OpenApiReference
{
Type = ReferenceType.SecurityScheme,
Id = "Bearer"
}
},
Array.Empty<string>()
}
});
});
public class SwaggerOptions : IConfigureOptions<SwaggerGenOptions>
{
private readonly IApiVersionDescriptionProvider provider;
/// <summary>
/// Initializes a new instance of the <see cref="SwaggerOptions"/> class.
/// </summary>
/// <param name="provider">The <see cref="IApiVersionDescriptionProvider">provider</see> used to generate Swagger documents.</param>
public SwaggerOptions(
IApiVersionDescriptionProvider provider)
{
this.provider = provider;
}
/// <inheritdoc />
public void Configure(
SwaggerGenOptions options)
{
// add a swagger document for each discovered API version
// note: you might choose to skip or document deprecated API versions differently
foreach (var description in provider.ApiVersionDescriptions)
{
options.SwaggerDoc(description.GroupName, CreateInfoForApiVersion(description));
}
}
private static OpenApiInfo CreateInfoForApiVersion(
ApiVersionDescription description)
{
var info = new OpenApiInfo
{
Title = "Demo API",
Version = description.ApiVersion.ToString(),
Description = "A sample application with Swagger, Swashbuckle, and API versioning.",
Contact = new OpenApiContact {Name = "DemoApi"},
License = new OpenApiLicense {Name = "MIT", Url = new Uri("https://opensource.org/licenses/MIT")}
};
if (description.IsDeprecated)
{
info.Description += " This API version has been deprecated.";
}
return info;
}
}
public static class SwaggerConfigExtension
{
public static IApplicationBuilder
ConfigureSwaggerUi(
this IApplicationBuilder app,
IApiVersionDescriptionProvider apiVersionProvider)
{
return app.UseSwaggerUI(
options =>
{
options.DocExpansion(Swashbuckle.AspNetCore.SwaggerUI.DocExpansion.Full);
foreach (var description in apiVersionProvider.ApiVersionDescriptions)
{
options.SwaggerEndpoint(
$"/swagger/{description.GroupName}/swagger.json",
description.GroupName.ToUpperInvariant());
}
}
);
}
}
Any help/direction would be appreciated.

Answer 1

Install nuget Microsoft.AspNetCore.Mvc.Versioning.ApiExplorer
Then in Startup.cs
public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IApiVersionDescriptionProvider apiVersionDescriptionProvider)
{
.....
app.UseSwaggerUI(c =>
{
foreach (var description in apiVersionDescriptionProvider.ApiVersionDescriptions.Reverse())
{
// Create the Swagger endpoints for each version
c.SwaggerEndpoint($"/swagger/" +
$"LibraryOpenAPISpecification{description.GroupName}/swagger.json",
description.GroupName.ToUpperInvariant());
}
c.RoutePrefix = ""; // swagger UI at the root index.html
});
....
}
see this answer: click here

Answer 2

In my case, I simply needed to sort the values in my SwaggerConfigExtension method returned from the IApiVersionDescriptionProvider. Here is my code with the Swagger drop-down list presenting versions in descending (latest to oldest) order.
public static class SwaggerConfigExtension
{
public static IApplicationBuilder
ConfigureSwaggerUi(
this IApplicationBuilder app,
IApiVersionDescriptionProvider apiVersionProvider)
{
return app.UseSwaggerUI(
options =>
{
options.DocExpansion(
Swashbuckle.AspNetCore.SwaggerUI.DocExpansion.List);
// Present API version in descending order
var versionDescriptions = apiVersionProvider
.ApiVersionDescriptions
.OrderByDescending(desc => desc.ApiVersion)
.ToList();
foreach (var description in versionDescriptions)
{
options.SwaggerEndpoint(
$"/swagger/{description.GroupName}/swagger.json",
description.GroupName.ToUpperInvariant());
}
}
);
}
}