I\'m implementing a prototype of a RESTful API using ASP.NET MVC and apart from the odd bug here and there I\'ve achieve all the requirements I set out at the start, apart f
You could create an ActionFilter that implements OnActionExecuting
, which fires before the controller action is invoked. You could then interrogate the request headers, and redirect based on the value of the X-HTTP-Method-Override
header, when present.
You won't be able to use the [AcceptVerbs] attribute as-is since it's tied to the request's actual HTTP verb. Fortunately the [AcceptVerbs] attribute is very simple; you can see the source for yourself at http://www.codeplex.com/aspnet/SourceControl/changeset/view/21528#266431.
In short, subclass AcceptsVerbsAttribute and override the IsValidForRequest() method. The implementation would be something like the following:
string incomingVerb = controllerContext.HttpContext.Request.Headers["X-HTTP-Method-Override"] ?? controllerContext.HttpContext.Request.Method;
return Verbs.Contains(incomingVerb, StringComparer.OrdinalIgnoreCase);
Have you looked at Simply Restful Routing? It already does this.
Edited Feb 2010 to add: Method overrides are built into MVC 2.
I'm surprised that this hasn't been mentioned yet, but ASP.NET MVC natively supports X-HTTP-Method-Override and has been doing so from at least version 2. There's no need to write custom code to handle this.
It work in the following way:
Inside AcceptVerbsAttribute (also proxied by [HttpPut], [HttpPost], etc), there's an IsValidForRequest method. Inside that method, it checks with Request.GetHttpMethodOverride(), which returns the proper overriden HTTP method with the following conditions:
If you're really curious, here's how GetHttpMethodOverride() looks (from MVC 3's source code):
public static class HttpRequestExtensions {
internal const string XHttpMethodOverrideKey = "X-HTTP-Method-Override";
public static string GetHttpMethodOverride(this HttpRequestBase request) {
if (request == null) {
throw new ArgumentNullException("request");
}
string incomingVerb = request.HttpMethod;
if (!String.Equals(incomingVerb, "POST", StringComparison.OrdinalIgnoreCase)) {
return incomingVerb;
}
string verbOverride = null;
string headerOverrideValue = request.Headers[XHttpMethodOverrideKey];
if (!String.IsNullOrEmpty(headerOverrideValue)) {
verbOverride = headerOverrideValue;
}
else {
string formOverrideValue = request.Form[XHttpMethodOverrideKey];
if (!String.IsNullOrEmpty(formOverrideValue)) {
verbOverride = formOverrideValue;
}
else {
string queryStringOverrideValue = request.QueryString[XHttpMethodOverrideKey];
if (!String.IsNullOrEmpty(queryStringOverrideValue)) {
verbOverride = queryStringOverrideValue;
}
}
}
if (verbOverride != null) {
if (!String.Equals(verbOverride, "GET", StringComparison.OrdinalIgnoreCase) &&
!String.Equals(verbOverride, "POST", StringComparison.OrdinalIgnoreCase)) {
incomingVerb = verbOverride;
}
}
return incomingVerb;
}
}
Levi's answer is great. Additionally, I added a check in the custom AcceptsVerbsAttribute that also examines the FORM collection, so you can simply put a hidden input to trigger the DELETE (similar to MVC 2's Html.HttpMethodOverride(HttpVerbs.Delete)
).
<input name="X-HTTP-Method-Override" type="hidden" value="DELETE" />
Change the incomingVerb assignment to:
string incomingVerb = controllerContext.HttpContext.Request.Headers["X-HTTP-Method-Override"] ?? controllerContext.HttpContext.Request.Form["X-HTTP-Method-Override"] ??controllerContext.HttpContext.Request.HttpMethod;
Be careful with this approach! See a related post by Stephen Walther.
Hopefully this helps someone.
This conversation is a bit old, but I wanted to share what I have found using mvc 2:
Browsers support two HTTP verbs: GET and POST, but ASP.NET MVC 2 allows you to simulate Put, Get, and Delete using Html.HttpMethodOverride helper method. Internally, this works by sending the verb in an X-HTTP-Method-Override form field. The behavior of HttpMethodOverride is used by the [AcceptVerbs] attribute as well as the new shorter verb attributes:
For example, the action declaration:
[ActionName("someresource")]
[HttpDelete]
public ActionResult DeleteSomeResource()
should take responsibility for your get request that has the X-HTTP-Method-Override set to Delete.