CODEWITHSUNDEEP
c#.net-coreapi-versioning
Binary Worrier
Binary Worrier

Reputation: 51719

Microsoft.AspNetCore.Mvc.Versioning how to default to the "latest" version

Other than changing startup.cs whenever a new version is built, 

services.AddApiVersioning(config =>
{
    config.DefaultApiVersion = new ApiVersion(1, 0);
});

is there a way of specifying that the "default version" is the latest version, without specifying what that version is? e.g. some way of saying

config.DefaultApiVersion = new ApiVersionLatest();

. . . or does this fly in the face of all that is considered holy by the RESTApi gods?

Thanks

Upvotes: 4

Views: 2086

Answers (1)

Chris Martinez
Chris Martinez

Reputation: 4418

The correct answer depends a little bit about what you expect to achieve. The DefaultApiVersion only comes into play when no other API version is available. API versioning does not have a concept of "no API version". API version-neutral means that an API accepts any and all API versions, including none at all. The default API version can also be thought of as the initial API version.

Here's a few scenarios where the DefaultAPiVersion comes into play:

  • A controller has no attribution or conventions applied
  • Selection of possible API versions yields no results

It sounds like you are interested in configuring the most current API version in a single place. You can use the DefaultApiVersion to do this, but only if the controller has no other attribution or conventions. If an API doesn't carry forward, you will have to explicitly decorate the controller with an attribute or convention that indicates the legacy API version to exclude it from the latest version. While this is possible, it's hard to follow IMO.

A better approach would probably to use an extension that that describes the behavior you want. For example:

[AttributeUsage( AttributeTargets.Class, AllowMultiple = false )]
public sealed class LatestApiVersionAttribute : ApiVersionAttribute, IApiVersionProvider
{
  public LatestApiVersionAttribute() : base( new ApiVersion( 2, 0 ) ) { }
}

Now you can apply this to all your controllers a la:

[LatestApiVersion]
public class MyController : ControllerBase
{
  // ommitted
}

This gives you the chance to manage the latest API version is single place. You might also consider using conventions so you don't even need the custom attribute. Attributes and conventions can be combined.

@spender does mention using a custom IApiVersionSelector; however, selection currently only comes into play when no API version has been specified. To enable this type of configuration, set things up as:

services.AddApiVersioning( options =>
{
   options.ApiVersionSelector = new CurrentImplementationApiVersionSelector( options );
   options.AssumeDefaultVersionWhenUnspecified = true;
}

This will enable clients that do not specify an API version to always forward to the most recent version of the requested API. A client can still explicitly ask for a specific version, including the latest.

I hope that helps.

Upvotes: 2

Related Questions