How to invoke one controller method from another given only the uri

Question

for simplicity consider a person resource such as

{"name":"Fred Flintston",
"worksAt":
   {"href":"api/sites?cn=Slate%20Rock%20and%20Gravel%20Company"}
}

When I receive this on the POST to the PeopleController I need to get the site resource from the worksAt.href.

What I would like to do is invoke the correct GET on the SitesController leveraging the routing engine that already knows how to parse the uri and invoke the correct method.

I have seen one suggestion here which seems rather heavy handed, and I'm not at all sure how that would allow the authorization that has already happened to carry through.

Answer 1

You can try the following, but if you describe in detail what you want to achieve, we might be able to find a better solution. It is MVC based, but should work for web API too.

var baseUrl = string.Format("{0}://{1}{2}", Request.Url.Scheme, Request.Url.Authority, Url.Content("~"));
var requestUrl = new Uri(baseUrl + "Home/Index?i=42");

//get method info
var httpContext = new HttpContextWrapper(new HttpContext(new HttpRequest("/", requestUrl.AbsoluteUri, ""), new HttpResponse(new StringWriter())));
var requestContext = new RequestContext(httpContext, RouteTable.Routes.GetRouteData(httpContext));
var controllerType = Assembly.GetExecutingAssembly().GetTypes().FirstOrDefault(x => x.Name == requestContext.RouteData.Values["controller"].ToString() + "Controller");
var controllerContext = new ControllerContext(requestContext, Activator.CreateInstance(controllerType) as ControllerBase);
var controllerDescriptor = new ReflectedControllerDescriptor(controllerType);
var actionDescriptor = controllerDescriptor.FindAction(controllerContext, controllerContext.RouteData.Values["action"].ToString());
var methodInfo = (actionDescriptor as ReflectedActionDescriptor).MethodInfo;

//parse the query string
var qscoll = HttpUtility.ParseQueryString(requestUrl.Query);
//and use the only item in it as an int when calling the action
var ret = methodInfo.Invoke(Activator.CreateInstance(controllerType), new object[] { int.Parse(qscoll[0]) });

The parameter passing is now baked in, so you'd need to create a correctly ordered parameter array, based on the parameter names, and types.