Controllers of ASP. NET MVC

The following is the definition of a controller:

    public class ProductController : Controller    {        //        // GET: /Product/        public ActionResult Index()        {            return View();        }        public ActionResult Help()        {            return View();        }        public ActionResult Details(int Id)        {            return View();        }    }

 

1. Understanding of return view () in action

That is, actionresult. Here return view () is actually to return HTML content to the page for display, while actionresult has many types:

· View ()-returns a viewresult.

· Partialview ()-returns a partialviewresult.

· Redirecttoaction ()-returns a redirecttorouteresult.

· Redirect ()-returns a redirectresult.

· Content ()-returns a contentresult.

· JSON ()-return a jsonresult.

· File ()-returns a fileresult.

· JavaScript ()-returns a javascriptresult.

· Redirecttoroute ()-returns a redirecttorouteresult.

Explanation:

· Viewresult-indicates a common ASP. net mvc view.

· Partialviewresult-indicates a piece of ASP. net mvc view.

· Redirectresult-Indicates redirecting to another controller action or URL.

return RedirectToAction("Index"); 

return RedirectToAction(“Index”, “Product”);

return RedirectToAction(“Details”, new {id=53});

 

· Contentresult-indicates to send some basic types of content to the browser. Any basic type of. Net can be string, Int, or double.

 public string SayHello()   {         return "Hello";   }

 

· Jsonresult-return a JSON type to the browser

          public ActionResult List()          {              var quotes = new List<string>              {                  "Look before you leap",                  "The early bird gets the worm",                  "All hat, no cattle"              };                            return Json(quotes);          }

 

· Fileresult-returns an object for download

        public ActionResult Download()          {                           return File("~/Content/CompanyPlans.docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "CompanyPlans.docx");          }    

 

· Emptyresult-no result is returned for an action.

· Httpunauthorizedresult-returned HTTP unauthorized status code.

· Javascriptresult-returns a Javascript file.

· Redirecttorouteresult-redirect to the action of another controller using route values

 

Ii. How to control the call of an action

1. Use acceptverbs

Check the Code:

        // GET: /Employee/Create          [AcceptVerbs(HttpVerbs.Get)]          public ActionResult Create()          {              return View();          }             // POST: /Employee/Create          [AcceptVerbs(HttpVerbs.Post)]          public ActionResult Create(Employee employeeToCreate)          {              try              {                  _repository.InsertEmployee(employeeToCreate);                  return RedirectToAction("Index");              }              catch              {                  return View();              }          }            // DELETE: /Employee/Delete/1          [AcceptVerbs(HttpVerbs.Delete)]          public ActionResult Delete(int id)          {              _repository.DeleteEmployee(id);              return Json(true);          }

 

It is used to control whether to trigger the create action during get or post operations.

Supported HTTP action types:

· Options-returns information about the communication options available.

· Get-returns whatever information is identified by the request.

· Head-performs the same operation as get without returning the message body.

· Post-posts new information or updates existing information.

· Put-posts new information or updates existing information.

· Delete-deletes information.

· Trace-performs a message loop back.

· Connect-used for SSL tunneling.

 

2. Use actionname

        [ActionName("Edit")]          [AcceptVerbs(HttpVerbs.Get)]          public ActionResult Edit_GET(Merchandise merchandiseToEdit)          {              return View(merchandiseToEdit);          }

 

3. Use actionmethodselector

namespace MvcApplication1.Selectors  {      public class AjaxMethod : ActionMethodSelectorAttribute      {          public override bool IsValidForRequest(ControllerContext controllerContext, MethodInfo methodInfo)          {              return controllerContext.HttpContext.Request.IsAjaxRequest();          }      }  } 

 

Code in controller:

        [AjaxMethod]          [ActionName("Index")]          public string Index_AJAX()          {              var selectedIndex = _rnd.Next(_news.Count);              return _news[selectedIndex];          }

3. Special processing: processing of actions not defined in the request

    public class CatalogController : Controller      {                   public ActionResult Create()          {              return View();          }            public ActionResult Delete(int id)          {              return View();          }              protected override void HandleUnknownAction(string actionName)          {              ViewData["actionName"] = actionName;              View("Unknown").ExecuteResult(this.ControllerContext);          }          }

 

Handleunkonwnaction is used. By default, the Error 404 resource not found is returned. You can reload the definition.