ASP.NET Web API 更改请求 URI（重定向到另一种方法）

Question

I have an ASP.NET project in which API versioning has been implemented via URL versioning. eg:

api/v1/Resource
api/v2/Resource

Now the requirement is that if a user requests a resource which is not available in that version, then it should fallback to previous version. Let's say user wants to access api/v2/SomeResource but the same is not available, then request should be forwarded to api/v1/SomeResource .

Can we intercept every incoming request and change the RequestURI before Route is decided?

I have tried using a DelegatingHandler to change the Request URI, but seems like route is decided before DelegatingHandler is executed.

protected override Task<HttpResponseMessage> SendAsync
    (HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
{
    request.RequestUri = new Uri(getNewURI(request.RequestUri.AbsoluteUri), UriKind.Absolute);
    return base.SendAsync(request, cancellationToken);
}

Is there anyway we can change the ReqestURI before Routing is finalized by Web API or any other way to accomplish this kind of redirection?

Answer 1

If you already know ahead of time that the route no longer exists (you would have to if you knew which route you wanted to redirect to) then you could just add multiple routes to the same method. Otherwise you would have to call the route to see if it existed, if it gave a 404 you would then have to attempt again with the next one and so on.

[HttpGet, Route("api/v2/resource")]
[HttpGet, Route("api/v1/resource")]
public IHttpActionResult YourMethod()
{

}