I'm trying to figure out how to pass a model across views
Here is what I'm doing, I have a Register, RegisterConfirm, RegisterComplete views.
User starts at Register, fills info, clicks continue and posts to RegisterConfirm where they click checkbox to agree to privacy policy then post to RegisterComplete which creates the user based on the model in the first Register view.
Code:
[GET("Account/Register")]
public ActionResult Register()
{
return View();
}
[POST("Account/Register/Confirm")]
public ActionResult RegisterConfirm(RegisterModel model)
{
if (ModelState.IsValid)
{
return View(model);
}
else { return View("Register", model); }
}
[POST("Account/Register/Complete")]
public ActionResult RegisterComplete(RegisterModel model, bool agree)
{
if (agree) {
// Create User
}
return View("Register", model);
}
View Form
Register:
#using (Html.BeginForm("RegisterConfirm", "Account", FormMethod.Post, new { #id = "create" }))
{
Register Confirm:
#using (Html.BeginForm("RegisterComplete", "Account", FormMethod.Post, new { #id = "create" }))
{
Problem is, when I'm getting to RegisterComplete, model values are empty... any ideas or is this not possible? Or should this work and I need to double check my registercomplete?
Is your RegisterConfirm view using display-only elements to show the registration information? If so, MVC won't be able to bind the data to populate the model.
You need to render the model as Input elements, even if they're hidden, so that the model binder can populate RegisterModel (you can render the properties as both hidden elements for 'data retention' and output elements for display).
If you are using Input elements, check that the names of those elements match the property names of RegisterModel, otherwise, again, the model binder won't be able to populate RegisterModel.
If you can't, for whatever reason, put the data in Input elements in your RegisterConfirm view, you'll need to store the data somewhere server-side, either in Session State (or TempData, which uses Session State anyway) or in a database of some description.
The advantage with storing the model server-side is that you can be sure that the data hasn't been tampered with between sending it to the client and receiving it back.
You can use TempData and store your model inside it and receive your model back from it
[POST("Account/Register/Confirm")]
public ActionResult RegisterConfirm(RegisterModel model)
{
if (ModelState.IsValid)
{
//store data for any other request
TempData["newUser"]=model;
return View();
}
else { return View("Register", model); }
}
[POST("Account/Register/Complete")]
public ActionResult RegisterComplete(RegisterModel model, bool agree)
{
//retrieve data back irrespective of use choice
//to clear memory
RegisterModel newUser= TempData["newUser"];
if (agree) {
// Create User
//use newUser
}
return View("Register", model);
}
Related
Could any body explain, when to use
TempData
ViewBag
ViewData
I have a requirement, where I need to set a value in a controller one, that controller will redirect to Controller Two and Controller Two will render the View.
I have tried to use ViewBag, the value gets lost by the time I reach Controller Two.
Can I know when to use and advantages or disadvantages?
Thanks
1)TempData
Allows you to store data that will survive for a redirect. Internally it uses the Session as backing store, after the redirect is made the data is automatically evicted. The pattern is the following:
public ActionResult Foo()
{
// store something into the tempdata that will be available during a single redirect
TempData["foo"] = "bar";
// you should always redirect if you store something into TempData to
// a controller action that will consume this data
return RedirectToAction("bar");
}
public ActionResult Bar()
{
var foo = TempData["foo"];
...
}
2)ViewBag, ViewData
Allows you to store data in a controller action that will be used in the corresponding view. This assumes that the action returns a view and doesn't redirect. Lives only during the current request.
The pattern is the following:
public ActionResult Foo()
{
ViewBag.Foo = "bar";
return View();
}
and in the view:
#ViewBag.Foo
or with ViewData:
public ActionResult Foo()
{
ViewData["Foo"] = "bar";
return View();
}
and in the view:
#ViewData["Foo"]
ViewBag is just a dynamic wrapper around ViewData and exists only in ASP.NET MVC 3.
This being said, none of those two constructs should ever be used. You should use view models and strongly typed views. So the correct pattern is the following:
View model:
public class MyViewModel
{
public string Foo { get; set; }
}
Action:
public Action Foo()
{
var model = new MyViewModel { Foo = "bar" };
return View(model);
}
Strongly typed view:
#model MyViewModel
#Model.Foo
After this brief introduction let's answer your question:
My requirement is I want to set a value in a controller one, that
controller will redirect to ControllerTwo and Controller2 will render
the View.
public class OneController: Controller
{
public ActionResult Index()
{
TempData["foo"] = "bar";
return RedirectToAction("index", "two");
}
}
public class TwoController: Controller
{
public ActionResult Index()
{
var model = new MyViewModel
{
Foo = TempData["foo"] as string
};
return View(model);
}
}
and the corresponding view (~/Views/Two/Index.cshtml):
#model MyViewModel
#Html.DisplayFor(x => x.Foo)
There are drawbacks of using TempData as well: if the user hits F5 on the target page the data will be lost.
Personally I don't use TempData neither. It's because internally it uses Session and I disable session in my applications. I prefer a more RESTful way to achieve this. Which is: in the first controller action that performs the redirect store the object in your data store and user the generated unique id when redirecting. Then on the target action use this id to fetch back the initially stored object:
public class OneController: Controller
{
public ActionResult Index()
{
var id = Repository.SaveData("foo");
return RedirectToAction("index", "two", new { id = id });
}
}
public class TwoController: Controller
{
public ActionResult Index(string id)
{
var model = new MyViewModel
{
Foo = Repository.GetData(id)
};
return View(model);
}
}
The view stays the same.
TempData
Basically it's like a DataReader, once read, data will be lost.
Check this Video
Example
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "Welcome to ASP.NET MVC!";
TempData["T"] = "T";
return RedirectToAction("About");
}
public ActionResult About()
{
return RedirectToAction("Test1");
}
public ActionResult Test1()
{
String str = TempData["T"]; //Output - T
return View();
}
}
If you pay attention to the above code, RedirectToAction has no impact over the TempData until TempData is read. So, once TempData is read, values will be lost.
How can i keep the TempData after reading?
Check the output in Action Method Test 1 and Test 2
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "Welcome to ASP.NET MVC!";
TempData["T"] = "T";
return RedirectToAction("About");
}
public ActionResult About()
{
return RedirectToAction("Test1");
}
public ActionResult Test1()
{
string Str = Convert.ToString(TempData["T"]);
TempData.Keep(); // Keep TempData
return RedirectToAction("Test2");
}
public ActionResult Test2()
{
string Str = Convert.ToString(TempData["T"]); //OutPut - T
return View();
}
}
If you pay attention to the above code, data is not lost after RedirectToAction as well as after Reading the Data and the reason is, We are using TempData.Keep(). is that
In this way you can make it persist as long as you wish in other controllers also.
ViewBag/ViewData
The Data will persist to the corresponding View
ViewBag, ViewData, TempData and View State in MVC
http://royalarun.blogspot.in/2013/08/viewbag-viewdata-tempdata-and-view.html
ASP.NET MVC offers us three options ViewData, VieBag and TempData for passing data from controller to view and in next request. ViewData and ViewBag are almost similar and TempData performs additional responsibility.
Similarities between ViewBag & ViewData :
Helps to maintain data when you move from controller to view. Used to
pass data from controller to corresponding view. Short life means
value becomes null when redirection occurs. This is because their goal
is to provide a way to communicate between controllers and views. It’s
a communication mechanism within the server call.
Difference between ViewBag & ViewData:
ViewData is a dictionary of objects that is derived from
ViewDataDictionary class and accessible using strings as keys. ViewBag
is a dynamic property that takes advantage of the new dynamic features
in C# 4.0. ViewData requires typecasting for complex data type and
check for null values to avoid error. ViewBag doesn’t require
typecasting for complex data type.
ViewBag & ViewData Example:
public ActionResult Index()
{
ViewBag.Name = "Arun Prakash";
return View();
}
public ActionResult Index()
{
ViewData["Name"] = "Arun Prakash";
return View();
}
In View, we call like below:
#ViewBag.Name
#ViewData["Name"]
TempData:
Helps to maintain data when you move from one controller to other
controller or from one action to other action. In other words when you
redirect, “Tempdata” helps to maintain data between those redirects.
It internally uses session variables. TempData is meant to be a very
short-lived instance, and you should only use it during the current
and the subsequent requests only
The only scenario where using TempData will reliably work is when you are redirecting. This is because a redirect kills the current request (and sends HTTP status code 302 Object Moved to the client), then creates a new request on the server to serve the redirected view.
It requires typecasting for complex data type and check for null values to avoid error.
public ActionResult Index()
{
var model = new Review()
{
Body = "Start",
Rating=5
};
TempData["ModelName"] = model;
return RedirectToAction("About");
}
public ActionResult About()
{
var model= TempData["ModelName"];
return View(model);
}
void Keep()
Calling this method with in the current action ensures that all the items in TempData are not removed at the end of the current request.
#model MyProject.Models.EmpModel;
#{
Layout = "~/Views/Shared/_Layout.cshtml";
ViewBag.Title = "About";
var tempDataEmployeet = TempData["emp"] as Employee; //need typcasting
TempData.Keep(); // retains all strings values
}
void Keep(string key)
Calling this method with in the current action ensures that specific item in TempData is not removed at the end of the current request.
#model MyProject.Models.EmpModel;
#{
Layout = "~/Views/Shared/_Layout.cshtml";
ViewBag.Title = "About";
var tempDataEmployeet = TempData["emp"] as Employee; //need typcasting
TempData.Keep("emp"); // retains only "emp" string values
}
TempData
will be always available until first read, once you read it its not available any more can be useful to pass quick message also to view that will be gone after first read.
ViewBag
Its more useful when passing quickly piece of data to the view, normally you should pass all data to the view through model , but there is cases when you model coming direct from class that is map into database like entity framework
in that case you don't what to change you model to pass a new piece of data, you can stick that into the viewbag
ViewData is just indexed version of ViewBag and was used before MVC3
Also the scope is different between viewbag and temptdata. viewbag is based on first view (not shared between action methods) but temptdata can be shared between an action method and just one another.
In asp.net mvc3 how to keep dropdown list selected item after postback.
Do something Like this :
[HttpPost]
public ActionResult Create(FormCollection collection)
{ if (TryUpdateModel(yourmodel))
{ //your logic
return RedirectToAction("Index");
}
int selectedvalue = Convert.ToInt32(collection["selectedValue"]);
ViewData["dropdownlist"] = new SelectList(getAllEvents.ToList(), "EventID", "Name", selectedvalue);// your dropdownlist
return View();
}
And in the View:
<%: Html.DropDownListFor(model => model.ProductID, (SelectList)ViewData["dropdownlist"])%>
Even easier, you can include the name(s) of your dropdowns in your ActionResult input parameters. Your dropdowns should be in form tags. When the ActionResult is posted to, ASP.Net will iterate through querystrings, form values and cookies. As long as you include your dropdown names, the selected values will be preserved.
Here I have a form with 3 dropdowns that posts to an ActionResult. The dropdown names are (non-case sensitive): ReportName, Year, and Month.
//MAKE SURE TO ACCEPT THE VALUES FOR REPORTNAME, YEAR, AND MONTH SO THAT THEY PERSIST IN THE DROPDOWNS EVEN AFTER POST!!!!
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult ReportSelection(string reportName, string year, string month)
{
PopulateFilterDrowdowns();
return View("NameOfMyView");
}
MVC does not use ViewState, which means you will need to manage the value persistence yourself. Typically this is done through your model. So, given that you have a view model, e.g.:
public class MyViewModel { }
And your controller:
public class MyController : Controller
{
public ActionResult Something()
{
return View(new MyViewModel());
}
public ActionResult Something(MyViewModel model)
{
if (!ModelState.IsValid)
return View(model);
return RedirectToAction("Index");
}
}
Now, when you pass the model back to the view with data (probably incorrect - failed validation), when you use your DropDownListFor method, just pass in the value:
#Model.DropDownListFor(m => m.Whatever, new SelectList(...))
... etc.
MVC's model binding will take care of the reading of the data into your model, you just need to ensure you pass that back to the view to show the same value again.
Assuming the selected item is part of the post, the controller now knows what it is. Simply have an entry in the ViewData dictionary indicating which item should be selected (null on get or if nothing was selected). In the view, check the value and if it's not null, select the appropriate option.
Use HttpRequestBase object.
In the view, this should work:
#Html.DropDownList("mydropdown", ViewBag.Itens as IEnumerable<SelectListItem>, new { value = Request["mydropdown"] })
If you are building the drop down list data source in the controller Action Method you can send the selected value to it
Controller:
public ActionResult Index( int serviceid=0)
{
// build the drop down list data source
List<Service> services = db.Service.ToList();
services.Insert(0, new Service() { ServiceID = 0, ServiceName = "All" });
// serviceid is the selected value you want to maintain
ViewBag.ServicesList = new SelectList(services, "ServiceID", "ServiceName",serviceid);
if (serviceid == 0)
{
//do something
}
else
{
// do another thing
}
return View();
}
View:
//ServiceList is coming from ViewBag
#Html.DropDownList("ServicesList", null, htmlAttributes: new { #class = "form-control" })
I have a registration form in the side bar of my web application. When the user submits the entered data, the user should be redirected to another page with a more complete registration form when he can fill the rest of the data. The data that was entered by the user in the first form should be already there in the second form, but that's not happening... I checked to see the value of the view model I'm passing to the second action method and it was null and in the browser's address bar I get:
http://localhost:2732/User/RegisterPage?model=Sharwe.MVC.ViewModels.RegisterPageViewModel
Here's the code:
public ActionResult Register()
{
return PartialView(new RegisterViewModel());
}
[HttpPost]
public ActionResult Register(RegisterViewModel dto)
{
var model = Mapper.Map<RegisterViewModel, RegisterPageViewModel>(dto);
return RedirectToAction("RegisterPage", "User", new { viewModel = model });
}
public ActionResult RegisterPage(RegisterPageViewModel viewModel)
{
return View(viewModel);
}
Isn't that the way to do this? Or am I missing something here...?
The Dictionary passed to RedirectToAction() is the Route Value not the View Model. And RedirectToAction() is basically telling the browser to go to a certain URL. Browser by default makes the GET request and obviously you lose your data.
For this, you need to use TempData dictionary. You can store view model in TempData and then RedirectToAction() to RegisterPage. TempData saves the data for only 1 request span and would delete it automatically. It's ideal for this scenario.
See this for more details > The value for a object inside a viewmodel lost on redirect to action in asp.net mvc 2.0?
In this particular case you don't need to use RedirectToAction, you can simply call the RegisterPage action directly:
[HttpPost]
public ActionResult Register(RegisterViewModel dto)
{
var model = Mapper.Map<RegisterViewModel, RegisterPageViewModel>(dto);
return RegisterPage(model);
}
public ActionResult RegisterPage(RegisterPageViewModel viewModel)
{
return View(viewModel);
}
In this code in an Edit view, the correct vendor name text appears but it is not validated when I blank its textbox and push Save. The Vendor is a property of the Order model, and VendorName is a property in the Vendor model. They relate referentially. My form does not all input into a single table, but on satellite tables as well.
<%= Html.TextBox("Vendor.VendorName")%>
<%= Html.ValidationMessage("Vendor.VendorName")%>
Why is validation not occuring?
This seems to work, but it seems like a hack to me:
using M = HelloUranus.Models
//...
namespace HelloUranus.Controllers
{
public class OrderDetailController : Controller
{
//...
private M.DBProxy db = new M.DBProxy();
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(int id, FormCollection collection)
{
//...
var orderDetail = db.GetOrderDetail(id);
//...
try
{
if (string.IsNullOrEmpty(Request.Form["Vendor.VendorName"]))
{
throw new Exception();
}
UpdateModel(orderDetail);
db.Save();
return RedirectToAction("Details", new {id = orderDetail.odID } );
}
catch
{
ModelState.AddRuleViolations(orderDetail.GetRuleViolations());
return View(orderDetail);
}
//...
}
//...
}
Did you write any validation code? You have to manually validate it in your controller. If you:
ModelState.IsValid = false;
in the controller, for example, you will see some validation. That will trigger the ValidationSummary on the View to be shown. To actually add a validation to a single form element, use:
ModelState.AddModelError("Vendor.VendorName", string.Format("Vendor name must be at least {0} characters.",10));
Note that this will also set the ModelState to an invalid state and thus trigger the ValidationSummary as well.
I'm passing data between my controller and my view using a ViewModel class. When there are validation errors, I return the ViewModel back to the view so the user can see the errors.
I'm having trouble figuring out the best way to deal with the data that is only passed from the controller to the view, which isn't passed back to the controller, such as the contents of dropdown lists.
Here's a simplified example from the project I'm working on:
I have a Widget object in my domain model that has an Employee property. I have a view that allows the user to edit this employee property by selecting their name from a drop down list.
public class WidgetFormViewModel {
// Used for a drop down list in the view
public SelectList EmployeeList { get; set; }
// This will contain the employee the user selected from the list
public int EmployeeID { get; set; }
public Widget Widget { get; set; }
}
And the controller:
// GET: /Widget/Edit/1
public ActionResult Edit(int id) {
var widget = _widgetService.GetWidgetByID(id);
var employees = _widgetService.GetAllEmployees();
var viewModel = new WidgetFormViewModel()
{
EmployeeList =
new SelectList(employees, "ID", "Name", widget.Employee),
Widget = widget,
WidgetID = widget.ID
};
return View("Edit", viewModel);
}
// POST: /Widget/Edit
public ActionResult Edit(WidgetFormViewModel viewModel) {
var existingWidget = _widgetService.GetWidgetByWidgetID(viewModel.WidgetID);
existingWidget.Employee = _widgetService.GetEmployeeByID(viewModel.EmployeeID);
// try { /* Save widget to DB */ } catch { /* Validation errors */ }
return ModelState.IsValid
// Update was successful
? (ActionResult) RedirectToAction("List")
// Model state is invalid, send the viewModel back to the view
: View("Edit", viewModel)
}
Now, here's the problem: When the ModelState is invalid and viewModel gets passed back to the view, its EmployeeList property is blank. What is the best way to deal with this?
Should I just repopulate it before returning to the view? This method seems difficult to maintain. (What if I add PageTitle and HeaderText to the view model as well? Suddenly there are more things to keep track of.) Is there another approach?
Inside of the catch block of the controller action handling the post, extract your error messages and add it to this.ModelState, then have it return this.Edit(viewModel.widgetID);.
You already have all the logic you need built up to display the view appropriately, you just want to use ModelState to make sure that errors make it back to the view.