Routing based on query string parameter name

问题:

I'm trying to configure routing in my MVC4 WebAPI project.

I want to be able to search for products based on their name or their type like so:

/api/products?name=WidgetX - returns all products named WidgetX /api/products?type=gadget - returns all products of type gadget

The routes are configured like this:

config.Routes.MapHttpRoute(
    name: "Get by name",
    routeTemplate: "api/products/{name}",
    defaults: new { controller = "ProductSearchApi", action = "GetProductsByName", name = string.Empty }
);

config.Routes.MapHttpRoute(
    name: "Get by type",
    routeTemplate: "api/products/{type}",
    defaults: new { controller = "ProductSearchApi", action = "GetProductsByType", type = string.Empty }
);

The problem is that the name of the query string parameter seems to be ignored so the first route is always the one used, regardless the name of the query string parameter. How can I modify my route to get it right?

回答1:

What you need is just only one route below because query string is not used as routing parameters:

config.Routes.MapHttpRoute(
    name: "Get Products",
    routeTemplate: "api/products",
    defaults: new { controller = "ProductSearchApi" }
);

And, then define two methods like below:

GetProductsByName(string name)
{}

GetProductsByType(string type)
{}

Routing mechanism is smart enough to route your url to your correct action based on the name of query string whether the same with input parameters. Of course on all methods with prefix are Get

You might need to read this: http://www.asp.net/web-api/overview/web-api-routing-and-actions/routing-and-action-selection

回答2:

You don't need to include your query parameters in the route. There should only be one simple route map to cover the Http Methods on all of your ApiControllers:

routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

The only time you need to adjust the routes is if you want to move a parameter into the actual path, which you don't seem to be doing. Then your GET http method to search by two fields would be:

public IEnumerable<Product> Get(string name, string type){
    //..your code will have to deal with nulls of each parameter
}

If you want to explicitly search by one field at a time then you should think about using different controllers for different purposes. Ie, a SearchProductByTypeController that has a single Get(string type) method. The route would then be /api/SearchProductByTypeController?type=gadget

回答3:

try changing string.Empty for RouteParameter.Optional

回答4:

Are you sure that the controllers are ok? I mean, the name of the params.

    public string GetProductsByName(string name)
    {
        return "Requested name: " + name;
    }

    public string GetProductsByType(string type)
    {
        return "Requested type: " + type;
    }