I have a controller method that needs to invoke (and get the HTML result from ) some other arbitrary "child" controller action. The route for the "child" action is encoded in a URL. What I want to do is parse the URL intro a route, get a controller that can execute the child action, simulate a request to the child action (obviously with some reasonable context), and then get the resulting HTML back.
I have tried a range of things (including an hour of trolling through SO posts on route parsing, creating controllers, etc.) but I'm stumped.
For example, ...
class SomeController
{
public ActionResult Outer()
{
string exampleInnerPath = "/Other/Child/20";
string output = EvaluateChildPath(exampleInnerPath);
return Content(output, "text/xml");
}
}
class OtherController
{
public PartialViewResult Child(int arg)
{
return PartialView(arg);
}
}
How would you write EvaluateChildPath()?
Any direction would be appreciated!
Related
In ASP.NET WebForms (well, HTML to be honest) we could reference pages within folders. EG, my structure could be (in regards to folders only)
root -> MyProductsFolder -> Shoes -> Ladies
And my website would show
www.mysite.com/MyProducts/Shoes/Ladies/Page.aspx
In MVC, we use a controller and it would appear that we can only ever have 1 level (folder) deep.
Is this right?
Without using URL rewriting, is it possible to have
www.mysite.com/MyProducts/Shoes/Ladies/Page
I assume the only way to do this is in the controller, but I can't create a controller named Shoes/Ladies
You can use MVC routing to created this URL. Your routing table is usually found in your AppStart > RouteConfig.cs class. You can use the route table to create URL maps to your actions in your controllers.
Assuming that MyProducts is your controller, and Shoes, Ladies are variables you want to accept you can do something like:
routes.MapRoute("MyProducts",
"MyProducts/{category}/{subcategory}/Page",
new { controller = "MyProducts", action = "Index" });
Note that your routes should be in order of most to least specific, so add this route above the default route.
When you navigate to /MyProducts/Shoes/Ladies/Page, it will map to your index action result in your MyProducts controller, passing variables for category and subcategory, so your controller will look something like
public class MyProducts : Controller
{
public ActionResult Index(string category, string subcategory)
{
//Do something with your variables here.
return View();
}
}
If my presumption is wrong, you want a view returned just for that URL, your route will look like:
routes.MapRoute("MyProducts", "MyProducts/Shoes/Ladies/Page", new { controller = "MyProducts", action = "LadiesShoes" });
And your Controller:
public class MyProducts : Controller
{
public ActionResult LadiesShoes()
{
//Do something with your variables here.
return View();
}
}
You can safely omit the final "/page" on the URL if you want to.
If I haven't covered your exact scenario with the above examples, let me know and I will extend my answer.
UPDATE
You can still put your views in a folder structure under the views folder if you want - and then reference the view file location in the controller - in the following example, place your view file called Index.cshtml in Views/Shoes/Ladies/ folder:
public class MyProducts : Controller
{
public ActionResult LadiesShoes()
{
//Do something with your variables here.
return View("~/Views/Shoes/Ladies/Index.cshtml");
}
public ActionResult MensShoes()
{
//Do something with your variables here.
return View("~/Views/Shoes/Mens/Index.cshtml");
}
}
You can use Attribute Routing to define the url of each action like below.
public class ShoeController : Controller
{
// eg: /nike/shoes/lady
[Route("{productName}/shoes/{xxx}")]
public ActionResult View(string productName, string xxx)
{
}
}
Routing Attribute offers flexibility and better code organization. You can check the route definition in the same spot.
Is there any useful hook in ASP.NET MVC (MVC4) which can let you access the Action method parameter (View model) before the action method becomes invoked, and then also (e.g. depending on the value of something you checked in the action method parameter) let you prevent the action method from being invoked, i.e. instead either forward the view model object (action method parameter) to another action method or directly to some view (i.e. without any further processing in an action method) ?
If you do not understand the question, please see the code example below which should illustrate the kind of code I am looking for...
(though I do not know if there actually exists such kind of interface and a possibility to hook an implementation into the MVC framework)
If this is indeed possible, I would like to see an answer with code example about how to do it (and not just a response with someone claiming that e.g. "try using method 'ActionFilterAttribute.OnActionExecuting' or 'IModelBinder.BindModel' " because I have already tried those and could not make it work).
Also, please respect that I do not want this thread to become a discussion about WHY to do it, but want to see HOW to do it.
(i.e. I am not interested in getting into discussions with responses such as "What are you actually trying to achieve?" or "There are probably better things of doing what you want to do...")
The question can be split into three subquestions/code examples as my own code samples below try to illustrate:
(but would like them "refactored" into REAL code with usage of real existing types)
(obviously, every type below which includes the substring "Some" is something I have made up, and I am looking for the corresponding real thing ...)
(1) Example of how to get access to (and potentially modify) view model objects (action method parameters) in a generic place before the actual action method is invoked with the view model object parameter.
The kind of code example I am looking for would probably be similar to below but do not know what kind of interface to use and how to register it to be able to do something like below:
public class SomeClass: ISomeInterface { // How to register this kind of hook in Application_Start ?
public void SomeMethodSomewhere(SomeActionMethodContext actionMethodContext, object actionMethodParameterViewModel) {
string nameOfTheControllerAboutToBeInvoked = actionMethodContext.ControllerName;
string nameOfTheActionMethodAboutToBeInvoked = actionMethodContext.MethodName;
// the above strings are not used below but just used for illustrating that the "context object" contains information about the action method to become invoked by the MVC framework
if(typeof(IMyBaseInterfaceForAllMyViewModels).IsAssignableFrom(actionMethodParameterViewModel.GetType())) {
IMyBaseInterfaceForAllMyViewModels viewModel = (IMyBaseInterfaceForAllMyViewModels) actionMethodParameterViewModel;
// check something in the view model:
if(viewModel.MyFirstGeneralPropertyInAllViewModels == "foo") {
// modify something in the view model before it will be passed to the target action method
viewModel.MySecondGeneralPropertyInAllViewModels = "bar";
}
}
}
}
(2) Example of how to prevent the targeted action method from being executed and instead invoke another action method.
The example might be an extension of the above example, with something like below:
public void SomeMethodSomewhere(SomeActionMethodContext actionMethodContext, object actionMethodParameterViewModel) {
... same as above ...
if(viewModel.MyFirstGeneralPropertyInAllViewModels == "foo") {
actionMethodContext.ControllerName = "SomeOtherController";
actionMethodContext.MethodName = "SomeOtherActionMethod";
// The above is just one example of how I imagine this kind of thing could be implemented with changing properties, and below is another example of doing it with a method invocation:
SomeHelper.PreventCurrentlyTargetedActionMethodFromBecomingExecutedAndInsteadExecuteActionMethod("SomeOtherController", "SomeOtherActionMethod", actionMethodParameterViewModel);
// Note that I do _NOT_ want to trigger a new http request with something like the method "Controller.RedirectToAction"
}
(3) Example of how to prevent the normal action method from being executed and instead forward the view model object directly to a view without any further processing.
The example would be an extension of the first above example, with something like below:
public void SomeMethodSomewhere(SomeActionMethodContext actionMethodContext, object actionMethodParameterViewModel) {
... same as the first example above ...
if(viewModel.MyFirstGeneralPropertyInAllViewModels == "foo") {
// the below used razor view must of course be implemented with a proper type for the model (e.g. interface 'IMyBaseInterfaceForAllMyViewModels' as used in first example above)
SomeHelper.PreventCurrentlyTargetedActionMethodFromBecomingExecutedAndInsteadForwardViewModelToView("SomeViewName.cshtml", actionMethodParameterViewModel);
}
You could use an action filter and override the OnActionExecuting event:
public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
...
}
}
Now let's see what useful information you could extract from this filterContext argument that is passed to this method. The property you should be looking for is called ActionParameters and represents an IDictionary<string, object>. As its name suggests this property contains all the parameters that are passed to the controller action by name and value.
So let's suppose that you have the following controller action:
[MyActionFilter]
public ActionResult Index(MyViewModel model)
{
...
}
Here's how you could retrieve the value of the view model after model binding:
public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var model = filterContext.ActionParameters["model"] as MyViewModel;
// do something with the model
// You could change some of its properties here
}
}
Now let's see the second part of your question. How to shortcircuit the controller action and redirect to another action?
This could be done by assigning a value to the Result property:
public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
... some processing here and you decide to redirect:
var routeValues = new RouteValueDictionary(new
{
controller = "somecontroller",
action = "someaction"
});
filterContext.Result = new RedirectToRouteResult(routeValues);
}
}
or for example you decide to shortcircuit the execution of the controller action and directly render a view:
public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var viewResult = new ViewResult
{
ViewName = "~/Views/FooBar/Baz.cshtml",
};
MyViewModel someModel = ... get the model you want to pass to the view
viewResult.ViewData.Model = model;
filterContext.Result = viewResult;
}
}
or you might decide to render a JSON result:
public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
MyViewModel someModel = ... get the model you want to pass to the view
filterContext.Result = new JsonResult
{
Data = model,
JsonRequestBehavior = JsonRequestBehavior.AllowGet
};
}
}
So as you can see the possibilities are unlimited of what you can do.
I have experimented with the code in the answer provided by the user Darin Dimitrov, and the first and third parts of the answer are correct.
(Though, for others who might find this thread and be interested, I can clarify that in the first answer the "model" does not seem to
be a hardcoded keyword always used for the model but seems to have to correspond to the chosen name of the action method parameter.
In other words, if you instead have the method signature
public ActionResult Index(MyViewModel myViewModel)
then in your action filter you have to use
var model = filterContext.ActionParameters["myViewModel"] as MyViewModel;
)
Regarding the second answer, the usage of 'RedirectToRouteResult' will trigger a new http request (which was not desired as I mentioned in the second code example of mine).
I found another way of "changing" action method by actually invoking it explicitly:
var controller = new SomeController();
ActionResult result = controller.SomeAction(model);
filterContext.Result = result;
The above code actually seems to prevent the originally targeted action method from becoming invoked, i.e. when I put a breakpoint in the method annotated with '[MyActionFilter]' the execution never got into that method.
Typically, it is probably not desired to hardcode a controller like above, but instead reflection might be used, for example as below with the thirdpart library "fasterflect":
string nameOfController = ...
string nameOfActionMethod = ...
// both above variables might for example be derived by using some naming convention and parsing the refering url, depending on what you want to do ...
var theController = this.GetType().Assembly.CreateInstance(nameOfController);
ActionResult result = (ActionResult)theController.CallMethod(nameOfActionMethod, model);
filterContext.Result = result;
(for those who want to extract the names of the current target controller and action method, when implementing logic to determine the controller you want to invoke, you can use this code in the filter:
var routeValueDictionary = filterContext.RouteData.Values;
string nameOfTargetedController = routeValueDictionary["controller"].ToString();
string nameOfTargetedActionMethod = routeValueDictionary["action"].ToString();
)
I think it feels a bit awkward to instantiate and invoke controllers like above, and would prefer to change the target controller and action method in another way if possible ?
So, the remaining question is if there is still (in MVC 4 final version) no way of redirecting/forwarding execution "internally" (without a new http request being fired as with 'RedirectToAction') at the server ?
Basically, I think I am here just looking for something like "Server.Transfer" which was used with ASP.NET Web Forms (and also the old classic ASP I believe could use the same thing).
I have seen older question/answers on this issue with people implementing this behaviour themselves with some "TransferResult" class of their own, but it seems to tend to become broken i different MVC versions.
(for example, see here for MVC 4 beta: How to redirect MVC action without returning 301? (using MVC 4 beta) ).
Is there really still not a simple standard solution (implemented in MVC 4 final) about how to do an "internal redirect" without a new http request (as RedirectToAction does) ?
I am writing an application wherein I need to send a System.Collections.ArrayList data as a parameter from one controller action to another.
I am using
return RedirectToAction("action1","controller1", new { arrList = arrListInFirstAction});
But since the ArrayList goes out of scope in the first action, the parameter in the redirected to action receives a null parameter.
Can someone please help me find an answer to this problem.
Thanks.
you can not send complex types as route parameters. you can, however, use TempData collection to keep that object for one request and on next request it will be automatically removed from collection
publci ActionResutl action()
{
TempData["arr"] = new int[]{1,2,3};
return RedirectToAction("action1");
}
Public ActionResult action1()
{
int[] arr = TempData["arr"];
return View();
}
I have the following controller:
class FooController : Controller
{
public ActionResult SomeAction(id)
{
Type t = Type.GetType(id);
object o = Activator.CreateInstance(t);
((MyModel)o).ParseParamaters(PostParameters); // I need to pass the post parameters here
//...
}
}
I would like to fetch all the POST parameters that were submitted.
How can it be done?
You do that with
[HttpPost]
public ActionResult SomeAction(id, FormCollection form)
{
//do what you want with the collection
}
I believe Request.Querystring is just a collection of strings, so you could pass it as a parameter to ParseParameters. Or you could just pass the whole Request object.
But I'm wondering why you'd want to, when there's perfectly good model binding built into MVC to do all the heavy lifting for you. http://weblogs.asp.net/nmarun/archive/2010/02/25/asp-net-mvc-model-binding.aspx
Is there a way to inject the referrer action from an action filter?
Lets say I have a view that comes from action X. In dies view I call action Y and I want to redirect again to action X. (There are multiple X actions that call action Y). I thought that it could be nice if I had a parameter call referrerAction and an action filter that filled it with the previous action. Is it possible?
Thanks.
Here's how I do:
public class ReturnPointAttribute : Attribute
{
}
public class BaseController: Controller
{
private string returnPointUrl = null;
protected override void OnActionExecuted(ActionExecutedContext filterContext)
{
base.OnActionExecuted(filterContext);
if (filterContext.ActionDescriptor.IsDefined(typeof(ReturnPointAttribute), true))
returnPointUrl = filterContext.HttpContext.Request.Url.ToString();
}
public ActionResult RedirectOrReturn<T>(Expression<Action<T>> action) where T : BaseController
{
return returnPointUrl.IsNullOrEmpty()
? MyControllerExtensions.RedirectToAction(this, action)
: (ActionResult)Redirect(returnPointUrl);
}
}
Now, you mark you X actions with [ReturnPoint] and call RedirectOrReturn() if you want to return back.
I do not use UrlReferrer because it can be wrong and I have no control over its value. With ReturnPoint, you can also have groups, e.g. [ReturnPoint("Orders")] and RedirectOrReturn("Orders").
Of course, you can have more automatic behaviour in OnActionExecuted - e.g. it can check if returned result is Redirect, and automatically go to ReturnPoint if it has value. Or you can control this with [ReturnPoint(Automatic=true)], and so on.