How to route Optional URI parameters to API Controller functions

Question

I am trying to set up an Asp.Net forms site with an API. I have succeeded in adding in selective authentication, so that pages starting "\api\" do not get redirected, but instead challenge for basic authentication. I am now trying to use MS Web Api 2 to do the API routing.

The idea is to be as RESTful as possible. I have a resource, a TradableItem, and initially I would want to allow API users to use HTTP GET in one of two ways.

If the API user passes no item key, the user receives a list of possible item keys

  ["ABC","DEF"...]

If the API user passes an item key as part of the URI, eg "/api/tradables/abc", a representation of the TradableItem is returned for the one with the key=ABC. (To my understanding, this is standard REST behaviour).

In Global.ASAX's Application_Start() function I have a route map like so...

    RouteTable.Routes.MapHttpRoute(
        name: "TradableItemVerbs",
        routeTemplate: "api/tradables/{item}",
        defaults: new { item = System.Web.Http.RouteParameter.Optional, controller = "Tradable" });

The TradableController.cs file looks like this...

public class TradableController : ApiController
{
    private static CustomLog logger = new CustomLog("TradableController");

    // GET api/<controller>
    public IEnumerable<string> GetKeys()
    {
    var prefix = "GetKeys() - ";
    string msg = "";

    msg = "Function called, returning list of tradable pkeys...";
    logger.Debug(prefix + msg);

    // Get a list of tradable items
    return TradableManager.GetTradablePkeys();
    }

    // GET api/<controller>/<pkey>
    public string GetTradable(string pkey)
    {
    string msg = string.Format("Would get Tradable data for key: >{0}<", pkey);
    return msg;
    }
}

The problem is that only the GetKeys() function fires, whether I call GET to "/api/tradables" or "/api/tradables/abc".

For reference, using VS2015 Community, IIS 7.5, targeting .Net 4.6.1. I used Rick Strahl's blog as a guide on this (among other sources).

http://weblog.west-wind.com/posts/2012/Aug/21/An-Introduction-to-ASPNET-Web-API#HTTPVerbRouting

Julito Avellaneda · Accepted Answer · 2015-12-21 18:15:23Z

1

please, change the name of your param to item (because, this is the name define in the routes):

public string GetTradable(string item)
{
    ....
}

or when you call the method be explicit with the parameter name: /api/tradables?pkey=abc

answered Dec 21, 2015 at 18:15

Julito Avellaneda

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2 Comments

Steve Hibbert Over a year ago

Thanks @julito-avellaneda, this worked. I was assuming the function would use the type, not the explicit name for the variable. Do you have any good links for WebAPI2 beginner tutorials (preferrably non MVC, but whatever).

Julito Avellaneda Over a year ago

Hi @SteveHibbert you can start with asp.net/web-api and next read the apress books: apress.com/catalogsearch/result/?q=web+api&submit=Go

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