Anyone have an example of RESTful URL's in ASP.NET MVC 2 RC that works?

Question

I have tried the code here:

http://dotnetslackers.com/articles/aspnet/Implementing-RESTful-Routes-and-Controllers-in-ASP-NET-MVC-2-0.aspx#s-reststyle-routes--controllers

But I just cannot get this to work with ASP.NET MVC 2.0 RC - the PUT and DELETE verbs do not get used. The output seems right, but the route handler seems to ignore the HttpMethodOverride.

I disabled the default route and now when I try to submit a form with the override set to PUT, the error "The HTTP verb POST used to access path '/contacts/2' is not allowed." is coming up. So it seems it is ignore the MethodOverride.

Answer 1

I found out why - the HttpMethodConstraint does not check the X-HTTP-Method-Override field and so, for example, in that article, the HttpMethodConstraint was set to only allow "PUT", but of couurse "POST" was being returned by HttpContext, so it failed.

I wrote my own RouteConstraint and have posted it here so others may learn from my trouble.

    public class HttpVerbConstraint : IRouteConstraint {

    public HttpVerbConstraint(params string[] allowedMethods) {
        if (allowedMethods == null) {
            throw new ArgumentNullException("allowedMethods");
        }
        this.AllowedMethods = allowedMethods.ToList<string>().AsReadOnly();
    }

    protected virtual bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection) {
        if (httpContext == null) {
            throw new ArgumentNullException("httpContext");
        }
        if (route == null) {
            throw new ArgumentNullException("route");
        }
        if (parameterName == null) {
            throw new ArgumentNullException("parameterName");
        }
        if (values == null) {
            throw new ArgumentNullException("values");
        }

        string method = httpContext.Request["X-HTTP-Method-Override"] ?? httpContext.Request.HttpMethod;

        switch (routeDirection) {
            case RouteDirection.IncomingRequest:
                return AllowedMethods.Any(v =>
                v.Equals(method, StringComparison.OrdinalIgnoreCase));
            case RouteDirection.UrlGeneration:
                string verb = "GET";
                if (values.ContainsKey(parameterName))
                    verb = values[parameterName].ToString();
                return AllowedMethods.Any(v =>
                    v.Equals(verb, StringComparison.OrdinalIgnoreCase));
        }
        return true;
    }

    bool IRouteConstraint.Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection) {
        return this.Match(httpContext, route, parameterName, values, routeDirection);
    }

    public ICollection<string> AllowedMethods { get; set; }

}