Run MVC controller action without the view? - asp.net-mvc

I have an ExcelResult action result that returns Microsoft Excel documents, based off the Stephen Walther tip. Basically it just writes a stream out to the Response. When debugging VS 2010 (ASP.NET Dev Server), it runs fine, but when I run it on an IIS 6 box, I get the following error:
The view 'GenerateExcel' or its master was not found. The following locations were searched:
~/Views/Home/GenerateExcel.aspx
~/Views/Home/GenerateExcel.ascx
~/Views/Shared/GenerateExcel.aspx
~/Views/Shared/GenerateExcel.ascx
There is no associated View, and therefore no file, but there shouldn't have to be. What am I doing wrong?
UPDATE
By simply returning void instead of an ActionResult, I no longer have this issue. Instead of returning the ExcelResult, I'm explicitly calling it's ExecuteResult method, which is writing to the output stream.
Before
public ActionResult GenerateExcel()
{
return this.Excel(parameters);
}
After
public void GenerateExcel()
{
ExcelResult excelResult = this.Excel(parameters);
excelResult.ExecuteResult(null);
}
After that, I had security issues with my NTLM authentication, but they 'went away' (meaning I expect them to come back). For now, though, everything is working properly.

Make sure your action method does not return a ActionResult:
public void DoSomething()

I didn't look at the code for the action result in much detail, but there must be something wrong with your action result. Did you inherit from some other action result as opposed to the ActionResult class? Did you call base.ExecuteResult? If so, that would explain why it is looking for the view. I have created several custom controller actions to return various file types and they never look for a view.
I agree with the comments on the answer saying to return void. That definitely is a hack. You should not call ExecuteResult from inside your action. You are basically writing directly to the response stream from your controller action. Obviously it works but it really doesn't fit the MVC model.

Related

A public action method '..' was not found on controller '..'

I wanted to put a random image on every viewpage of my mvc project. So i created a method that returns a partialView and call that method in the shared Layout page.
This works fine when I try to login with a correct username and password. The used is loged in and every page contains a random image. But when I give the invalid combination of username and password. The shared layout page does not find the controller I want to call with my #Html.Action and actualy the login view should be returned with an error message 'invalid combination of username and password' and ofcourse, with the random image.
InnerException:
{"A public action method 'RandomSponsor' was not found on controller 'Project.WebUI.Controllers.HomeController'."}
My Html.Action in shared layout.
#Html.Action("RandomSponsor", "Home")
Method in homecontroller.
[HttpGet]
[ChildActionOnly]
public ActionResult RandomSponsor()
{
var model = service.getRandomSponsor();
return PartialView("RandomSponsor", model);
}
The getRandomSponsor method works fine, this one always returns one random string value that is returned to the RandomSponsor.cshtml view.
RandomSponsor.schtml (only contains the image string)
<img src="~/Content/Images/Advert/#(Model)" alt="a" />
I searched the web for this problem but didn't found a solution, does anyone know the answer to this one?
Might it be something with HttpGet of HttpPost?
Regards.
If the executing request is a POST, then it will try to find a method RandomSponsor accepting HttpPost. If this makes sense, you could remove HttpGet and that should do the trick.
This can also happen if you have many layers of calls that start with a POST (I had an action returning a view returning a partial view calling RenderAction), then the call to RenderAction will still look for a POST method
Very similar to this problem that I had here - How to solve "public action method 'methodActionName' was not found on controller 'controllerNameController'"
And if you want to continue to accept the HTTP GET verb and fix the problem of cascading post request into a get request add this to your method
[AcceptVerbs(HttpVerbs.Get | HttpVerbs.Post)]
Keep in mind that [HttpGet] is the same as [AcceptVerbs(HttpVerbs.Get)]
This will happen if the request is a POST but the controller method is annotated [HttpGet]. For example, you might issue a POST that returns a view containing partial views called with #Html.Action, using controller methods annotated with [HttpGet]. If the original request is a POST, all of the controller methods subsequently called will need to support POST.
To fix it you can use the AcceptVerbs attribute to specify that your controller method accepts both POST and GET:
[AcceptVerbs(HttpVerbs.Post | HttpVerbs.Get)]
Received this error all of the sudden on several different PartialViews (not all of them) when customizing an install of MVCForum. We had not made any changes to the methods or views concerning the errors so it was really frustrating as to why they were broken.
After trying the other solutions on this post and others, went back through the changes made and what ended up stopping the errors was that we had changed the bindings in IIS to another domain that had the 'enforce lower case url' URL Rewrite rule enabled.
When we disabled the enforce lowercase rule, the errors stopped and the site worked as it was supposed to. It's not a URL Rewrite issue (I don't think) because we are able to enforce www using it with no errors. It's a lowercase rewrite issue. Didn't matter if we had the lowercase rule before or after the www rule.
This solution probably doesn't apply to many cases of this error, but it worked for us. Hopefully someone else can benefit from such a simple fix.
I just solved this issue strangely enough on my local PC, by making sure my entire request path was lower case. So give that a try.
I know this is a pretty old thread - but as it's top Google result I thought I'd add a potentially missing link for MVC.Net 5.2.6.
Scenario
I was attempting to call a child action via #Html.Action("ActionName", new { Id = 123})
and received an error much like the above, but none of the other solutions worked. I could hit the controller action externally (i.e. HttpGet), but the child action kept throwing the exception and was driving me nuts!
The solution I found
After two-ing and fro-ing for some time, I started playing with my routing attributes. I had the controller set up as:
[Route("{action}")]
[RoutePrefix("Prefix")]
[RouteArea("AreaName")]
As there was only one public action i wanted, "Index", I removed the {action} and placed an explicit route attribute on the public action and put my ChildActionOnly attribute back on the child.
After I did that, I hit the run and hey presto - the action was hit.
Might be worth a try if you're getting this error while using attribute routing. Note I did attempt to route the child action and this didn't work.
In my case, the same issue was happening randomly with the implicit :
using (Html.BeginForm())
Changing above to :
using (Html.BeginForm("Action","Controller", FormMethod.Post))
fixed this issue.
Did you give it a shot with Html.RenderAction? It is typically faster then Html.Action as it interact directly into the response stream as opposed to building a string.
You can view the following topics for more info:
What is the difference (if any) between Html.Partial(view, model) and Html.RenderPartial(view,model) in MVC2?
Html.Partial vs Html.RenderPartial & Html.Action vs Html.RenderAction
Another thing to note is that for Html.Action or Html.RenderAction, your view doesn't need to be in Shared folder, that is only required if you use Html.Partial or Html.RenderPartial

Overloading of public functions in Controller

I am new to MVC. I was going through the asp.net site and found this link where it stated that public methods (actions) cannot be overloaded in controller classes. However in the site it stated that it can be only be possible if i use [AcceptVerbs(HttpVerbs.Post)] with one function.
Can you please explain how does AcceptVerbs helps in overloading the function.What it actually does behind the scene?
And in one of my sample application i am able to overload the function by using [HttpPost] in one function.What else can be used for overloading?
Basically the rule is that you can handle this when it is responding to different types of requests, so Post/Get/Delete. (Any of the items in the HttpVerbs enumeration)
It is due to the way that it does resolution of the method to call in the controller, and specifying the method allows it to handle resolution.
In ASP.NET MVC, incoming request url should match action of controller. In MVC request processing pipeline, first the controller action is selected, and then the parameters for it are inspected and populated. Imagine what happened if controller had two methods with same name but different signature (overloaded).The c# compiler does not complain, as it understands the code, because it can distinguish between methods based on its parameter signature. But ASP.NET MVC request matching mechanism, as mentioned above, cannot - it first does search for action and only after action is selected, it takes look at its parameters. Because of this, "Public actions in controllers cannot be overloaded" - if there're no difference between methods(actions) other than parameters, action selection in MVC will fail to unambiguously select one. This's where ActionMethodSelectorAttribute comes into play. This is the base mechanism for developers to affect the way MVC searches for valid action in specified controller. It has the method IsValidForRequest() that tells MVC wether action can be selected for usage or not. All of [AcceptVerbs], [HttpGet], [HttpPost], [HttpPut], [HttpDelete] and [HttpNonAction] derive from this attribute. And bingo - now the method overloading is possible - although actions have got the same name, one of the attributes above (or your custom attribute derived from ActionMethodSelectorAttribute) can tell MVC wchich action to select and which one to not. And MVC now unambigously knows wchich action is valid for request. Consider example
[HttpGet]
public ActionResult Index()
{
// The above HttpGet.IsValidForRequest() called internally
by mvc will return true only if request is made via HTTP GET
}
[HttpPost]
public ActionResult Index(MyModel model)
{
// The above HttpPost.IsValidForRequest() called internally
by mvc will return true only if request is made via HTTP POST
}
// And so forth with other ActionMethodSelectorAttibute s. As you see, only one action from same named ones is valid for single request when decorated with any of builtin ActionMethodSelectorAttibute

ASP.NET MVC - Wrong redirecting, how to debug?

I am stuck with redirecting problem in ASP.NET MVC project. I have mapped tables via LINQtoSQL and each has unique ID as primary key.
I am implementing functionallity of 'CREATE'. Basically, after new value is added into SQL table (which means I pressed Save button), I want to be redirected to Details of this freshly added item.
Here's little code how I am doing it :
[AcceptVerbs(HttpVerbs.Post), Authorize]
public ActionResult Create(Item item) {
....
return RedirectToAction("Details", new { id = item.ItemID });
Trouble is, I am never redirected to Details view (I have Details.aspx view for items).
When I check CallHierarchy in Visual Studio (2010 pro) the hierarchy is indeed little strange, like this :
RedirectToAction(string,object)
Calls To 'RedirectToAction'
Create
Calls To Create (no results)
Calls From Create (methods of created instance. From there I'll get back to 'RedirectToAction' and to 'Calls to Create' and 'Calls From Create' etc. etc. - loop
Edit
Calls From 'RedirectToAction'
Not supported
I am looking for some tools or more specifically 'know how' (since VS probably has some tools) to debug this kind of situations.
PS: rooting is default :"{controller}/{action}/{id}",
Thanks
Checck your routes with Phil Haack's Route Debugger. Make sure that the correct route is being used, and the correct controller method is being called.
Use the debugger to step to the line where RedirectToAction is called. Confirm that the line is realy hit. Press F5 to continue after it.
Once the code is executed check in Firebug under network if a 302 is emitted.
See what is in the details for the request.
If no 302 is emitted I would try return RedirectToAction("Index") just to know if the call to details is wrong or there is another error.
You would need in the same controller
public ActionResult Details(int id)
{
return View();
}
in additon to the Details.aspx view.

Controller equivalent of HttpContext.Current in ASP.NET MVC

I'd like to get access to the current executing Controller so I can offload the return of the appropriate ActionResult onto a helper method. To this end, I'm looking for the equivalent of what I would have thought would be ControllerContext.Current but isn't. Thanks!
Edit for clarification: I've got a generic form control which is JavaScript-based but I'd like to add an option so that it works with noscript. At the moment my Controller sets the ViewData.Model to a JSON-ified Models.FormResponse<T>.
This FormReponse is set up with the status of the post and any error messages that were generated, so I'd like a GetActionResult() method which does the script/noscript check (a hidden form input) and either:
Sets the Model to the JSONed FormResponse and returns a View(), or
Serializes the FormResponse to the Session and returns a Redirect().
As this obviously changes the return value and I don't want to do the check myself every time, I need to call View or Redirect from the FormResponse's GetActionResult method in order to call this as:
return formResponse.GetActionResult();
I know with a more astronautical design this could be made even more robust but as the noscript option is not a major feature at the moment, I just need to get a quick solution working that doesn't break other things.
Update #2
The following, implemented in an ActionResult class, does the job for me. Thanks CVertex!
public override void ExecuteResult(ControllerContext context)
{
if (CMSEnvironment.NoScript)
{
Oracle.Response.Redirect(Oracle.Request.UrlReferrer.ToString(), true);
}
context.Controller.ViewData.Model = _model.ToJSON();
new ViewResult()
{
ViewName = Areas.Site.Helpers.SharedView.Service,
ViewData = context.Controller.ViewData
}.ExecuteResult(context);
}
Statics are bad for testability, and very much discouraged in MVC.
Why do you want to access the current controller and action method?
The best way to do this is to implement your own ActionFilter.
This gives you a means of intercepting requests before or after actions methods execute.
EDIT:
By intercepting the result inside OnActionExecuted of a filter, you can do your noscript/script checks and modify your ViewData accordingly for consumption by the View.
Inside OnActionExecuted, you can also do the noscript check and have complete control over the final ActionResult or the ViewData, as you please.
Or, you can write your own ActionResult that makes all these decisions.
So, your controller action ultimately does
return new MyActionResult(format_and_view_agnostic_model_object);
There doesn't appear to be a way to navigate to the current Controller from a thread. That is you could get the ControllerBuilder and you can get the MvcHttpHandler but neither then lets you access the controller instance that the handler is using.

What's the point of ActionResult return type?

What is the point of an action returning ActionResult?
Returning an ActionResult instead of "just doing whatever the ActionResult is doing" (i.e. using Response.Redirect directly or trying to render out a View through the Response OutputStream directly) gives you one really nice advantage: Unit Testing is really easy on that, especially since you normally do not need a web server to unit test MVC Projects.
Addendum: As an example for a redirect:
If you do
return Redirect(newUrl);
in your controller, your Unit Test can now
Verify that the return value is of Type "RedirectResult"
Look at the URL that is being redirected to by checking result.Url after casting it to RedirectResult
All without having to spin up IIS or trying to "clevery" intercept the Response.Redirect call
At the end of the day, RedirectResult calls Response.Redirect in it's ExecuteResult function, but your Controller Unit Test sits in front of that
Addendum 2: And while I am on it, here is an example of a Custom ActionResult:
http://www.stum.de/2008/10/22/permanentredirectresult/
This is just to show that they are not "Black Magic". They are actually pretty simple: Your Controller returns an Action Result, and the MVC Runtime will eventually call the ExecuteResult function on it, passing in a ControllerContext that your ActionResult can interact with. The whole point again is to separate the parts of M-V-C, to make Code Reusable, and to make Unit testing easier, or in short: To give a very clean Framework.
Since it is the base class, it allows you to return any of the ActionResult subclasses, such as ViewResult or JsonResult. I typically return ViewResult as the default, but override that behavior if I am dealing with Ajax to return a JsonResult object.
This allows me to add Ajax as a progressive enhancement and keep the application working without JavaScript and without the need for separate controller actions.
ActionResult is the base class for many different types of controller results. By returning the base class, the controller action can return different types of results depending on the outcome of the method -- a ViewResult, a RedirectToActionResult, etc. ActionResult contains all of the data needed by the View or new Action that is the result of the current controller action.

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