Hi Everyone , I am new to MVC but have programmed before. I have setup an error controller
which can be called when an error occurs in the main controller. My aim is to have one error view , which I can pass in the relevant error messages.
In the code below I am calling the error controller to displays the index view when there no record is returned from the product list
Here is my main controller
public ActionResult Details(int ProductID)
{
var model = db.Get(ProductID);
if (model == null)
{
//return RedirectToAction("Index", "ErrorController");
return errorController.Index("Record not Found", "The Product you are looking for is no longer available");
}
return View(model);
}
And this is my Error Controller that it calls successfully
public ActionResult Index(string errorTitle, string errorMessage)
{
ViewBag.ErrorTitle = errorTitle;
ViewBag.ErrorMessage = errorMessage;
return View();
}
At the moment the Index Action Result is called and the view returned but the details view from the original controller is also called, which causes an error as there is no records .
So my Error view is not being displayed .
How can I stop the original details view from being called ?
Any help would be great
Thanks
Try this-
return RedirectToAction("Index", "Error", new {
ErrorTitle = "Record not Found",
ErrorMessage = "The Product you are looking for is no longer available"
});
You basically need to redirect to the error controller and pass in the params as part of the route. RedirectToAction takes a parameter of RouteValues
Also you do not need "ErrorController", you can just use "Error"
Okay so generally in .net you don't want to pass along errors with redirects like that, instead you should use a library like Vereyon.Web FlashMessageCore which will help you with redirecting errors to the user in an easy and concise way.
However, if you want to do it that way (totally fine) you still need to pass the error title and error message like so in the redirect to action call:
return RedirectToAction("Index", "Error", new {errorTitle="error", errorMessage="message"});
Related
I have a controller with an Index method that has several optional parameters for filtering results that are returned to the view.
public ActionResult Index(string searchString, string location, string status) {
...
product = repository.GetProducts(string searchString, string location, string status);
return View(product);
}
I would like to implement the PRG Pattern like below but I'm not sure how to go about it.
[HttpPost]
public ActionResult Index(ViewModel model) {
...
if (ModelState.IsValid) {
product = repository.GetProducts(model);
return RedirectToAction(); // Not sure how to handle the redirect
}
return View(model);
}
My understanding is that you should not use this pattern if:
You do not need to use this pattern unless you have actually stored some data (I'm not)
You would not use this pattern to avoid the "Are you sure you want to resubmit" message from IE when refreshing the page (guilty)
Should I be trying to use this pattern? If so, how would I go about this?
Thanks!
PRG Stands for Post-Redirect-Get. that means when you post some data to the server back, you should redirect to a GET Action.
Why do we need to do this ?
Imagine you have Form where you enter the customer registration information and clicking on submit where it posts to an HttpPost action method. You are reading the data from the Form and Saving it to a database and you are not doing the redirect. Instead you are staying on the same page. Now if you refresh your browser ( just press F5 button) The browser will again do a similar form posting and your HttpPost Action method will again do the same thing. ie; It will save the same form data again. This is a problem. To avoid this problem, We use PRG pattern.
In PRG, You click on submit and The HttpPost Action method will save your data (or whatever it has to do) and Then do a Redirect to a Get Request. So the browser will send a Get Request to that Action
RedirectToAction method returns an HTTP 302 response to the browser, which causes the browser to make a GET request to the specified action.
[HttpPost]
public ActionResult SaveCustemer(string name,string age)
{
//Save the customer here
return RedirectToAction("CustomerList");
}
The above code will save data and the redirect to the Customer List action method. So your browser url will be now http://yourdomain/yourcontroller/CustomerList. Now if you refresh the browser. IT will not save the duplicate data. it will simply load the CustomerList page.
In your search Action method, You dont need to do a Redirect to a Get Action. You have the search results in the products variable. Just Pass that to the required view to show the results. You dont need to worry about duplicate form posting . So you are good with that.
[HttpPost]
public ActionResult Index(ViewModel model) {
if (ModelState.IsValid) {
var products = repository.GetProducts(model);
return View(products)
}
return View(model);
}
A redirect is just an ActionResult that is another action. So if you had an action called SearchResults you would simply say
return RedirectToAction("SearchResults");
If the action is in another controller...
return RedirectToAction("SearchResults", "ControllerName");
With parameter...
return RedirectToAction("SearchResults", "ControllerName", new { parameterName = model.PropertyName });
Update
It occurred to me that you might also want the option to send a complex object to the next action, in which case you have limited options, TempData is the preferred method
Using your method
[HttpPost]
public ActionResult Index(ViewModel model) {
...
if (ModelState.IsValid) {
product = repository.GetProducts(model);
TempData["Product"] = product;
return RedirectToAction("NextAction");
}
return View(model);
}
public ActionResult NextAction() {
var model = new Product();
if(TempData["Product"] != null)
model = (Product)TempData["Product"];
Return View(model);
}
In a controller a error with Create/Edit ActionResult can be handled with a try-catch block with the error being displayed on the view (via ModelState.AddModelError).
Now I am trying something similar with the DeleteConfirmed ActionResult but there is no error appearing on the view page. The table I am trying to delete from should be complaining about deleting a foreign-key field value.
Should I RedirectToAction differently or add something else?
[HttpPost, ActionName("Delete")]
public ActionResult DeleteConfirmed(int id)
{
try
{
StatusList statuslist = db.Status.Find(id);
db.Status.Remove(statuslist);
db.SaveChanges();
}
catch (DataException dex)
{
ModelState.AddModelError("", dex.Message);
return RedirectToAction("Delete");
}
return RedirectToAction("Index");
}
If you do a redirect, you lost the ModelState.
So you can do two things imo.
Setting the error message in TempData["myerrorkey"] = dex.Message, so the message will "survive" for one redirect
Change your method and, in case of error, return a View so that the model state is not wiped out during the redirect
Personally I will choose the first. so you can think also to implement TempData in case of a delete telling the user, in the index page, that everything went smooth.
I got an action List
//[HttpGet] (will come back to that!)
public ViewResult List(int page = 1)
{
//blah blah blah
return View(viewModel);
}
In its view we render action:
#{
Html.RenderAction("UpdateSearch");
}
Action definitions:
[ChildActionOnly]
[HttpGet]
public PartialViewResult UpdateSearch()
{
// do something and display a form in view
return PartialView(so);
}
[HttpPost]
public RedirectToRouteResult UpdateSearch(Options searchOptions)
{
// do something and redirect to List
return RedirectToAction("List");
}
and I'm getting: Child actions are not allowed to perform redirect actions exception every time someone submits the form. I'm new to MVC3, but it looks like the redirection is also a POST, because if [HttpGet] above List method is uncommented "the resource cannot be found" happens.
How do I change Http method on redirection or am I doing something wrong? I did try to Bing it, but no success.
The redirect info is stored in response header. However, the response is already being sent when child action is run so headers can't be written.
In short, there's no way of performing a redirect from child action other than through the use of javascript on client side.
I have an Account controller which have:
LoginForm (get action)
Login (post action)
RegisterForm (get action)
Register (post action)
In another controller's index action i use render them as:
Html.RenderAction("RegistrationForm", "Acount");
Html.RenderAction("LoginForm ", "Acount");
Everything works ok and I can register a new user, login and validate with unobtrusive validation.
The problem is when do some back-end validation in Register/Login action and if there is an error I don't know how to transfer the error to be rendered.
I've tried with PRG pattern and it works ok. I get the error displayed on the form with the preserved data, but PRG is not the way to do it.
What is an alternative solution to this problem without using ajax to validate or move those methods in the controller where the RegistrationForm/LoginForms are used?
I want to skip using TempData due to session usage in the background.
EDIT CODE SAMPLE:
class AccountController : SomeBaseController{
[HttpGet]
public PartialViewResult RegistrationForm()
{
return PartialView(new RegisterUser());
}
[HttpPost]
public ActionResult RegisterUser(RegisterUser user)
{
if (ModelState.IsValid)
{
var _user;// create domain user from Register user Model;
var _validationOutput = _userService.DoSomeAwsomeServerSideValidation(_user);// do some custom validation
if (_validationOutput.IsFault)
{
// we preseve tempdata in base controller OnActionExecuted
_validationOutput.ErrorMessages.ForEach(x => ModelState.AddModelError(_validationOutput.ErrorCode, _validationOutput));
// redirect to home controller custom error occured
return RedirectToAction("Index", "Home", user);
}
return RedirectToAction("RegistrationInfo");
}
return RedirectToAction("SomeUserInfoAction");
}
}
class HomeController : SomeBaseController {
Index(){
return View();
}}
HomeControllerMarkup {
#{Html.RenderAction("RegistrationForm", "Acount");}
#{Html.RenderAction("LoginForm", "Acount");}
}
You can manually add errors to your ModelState within your post controller using:
ModelState.AddModelError("", #"You didn't perform task XYZ");
You should then be able to return the view and display the errors in a validation summary:
#Html.ValidationSummary(false, "Login was unsuccessful because...")
I am trying to pass a random string from my Controller to the View.
Here is my Controller code:
[HttpPost]
public ActionResult DisplayForm(UserView user)
{
//some data processing over here
ViewData["choice"] = "Apple";
return RedirectToAction("Next", "Account");
}
Now I want to pass that data value "Apple" to my view Next.cshtml which is created as follows:
//View: Next.cshtml
#{
ViewBag.Title = "Thanks for registering";
Layout = "~/Content/orangeflower/_layout.cshtml";
}
<p>Your favorite fruit is:</p>#ViewData["choice"]
But I am not able to see my data in the browser when the project runs.
Here is the snapshot:
1) On debug, the controller showing the value:
2) The browser view doesn't show the value "Apple"
3) On further debug to my Next.cshtml View:
Why is the value not getting passed to the View correctly. Both my controllers for Next and DisplayForm are within the same Controller AccountController.cs , still value not getting displayed.
Can someone help me solve this ?
You are not rendering a view, you are redirecting. If you wanted to pass some information tyo the view you need to return this view after adding it to ViewData:
[HttpPost]
public ActionResult DisplayForm(UserView user)
{
//some data processing over here
ViewData["choice"] = "Apple";
return View();
}
If you want to pass a message that will survive after a redirect you could use TempData instead of ViewData.
[HttpPost]
public ActionResult DisplayForm(UserView user)
{
//some data processing over here
TempData["choice"] = "Apple";
return RedirectToAction("Next", "Account");
}
then inside the Next action you could fetch the data from TempData and store it inside ViewData so that the view can read it.
You are performing a post - redirect - get. The ViewData is being set for this request, which returns a redirect, clearing the ViewData, then another request happens which does not have the data. Use TempData instead and it will be added to the ViewData automatically on the next request.