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Passing Data from View to Model in MVC in c#

I am new to ASP.NET MVC. Is it possible to pass data from view to model in mvc? this question was asked in interview.Please anyone give me right answer.
Thanks in Advance

To pass data to controller through model you should wrap all the inputs (checkboxes, textboxes, radio etc.) with <form ...> tag. You could do it using HTML tag or with help of ASP.NET MVC helper #Html.BeginForm(...). Once you submit your form, all the input data will be sent to a controller action and mapped to a targeted model. Please see an example:
Model:
public class UserModel
{
public string FirstName { get; set; }
public string LastName { get; set; }
}
View:
#model UserModel
#using (Html.BeginForm("Search", "Events"))
{
#Html.TextBoxFor(m => m.FirstName)
#Html.TextBoxFor(m => m.LastName)
<input type="submit" value="Search" />
}
Controller:
public class EventsController: Controller
{
public ActionResult Search(UserModel model)
{
//do something
return View(); //return "Search" view to the user
//return View(model); //You can also return view with the model to the user
//return View("SpecificView"); //You can specify a concrete view name as well
}
}

No, we do not pass any information from view to model directly, both the view and model are different module. we can pass data, value or any information from view to model via controller.

Let textboxfor display the value it updates

I got this textbox in my view inside a beginform:
#Html.TextBoxFor(m => m.Page.logoUrl)
When i submit, the value i put in the textbox updates the db..
I would like the textbox to display the value from the db when the
page loads.

I often use a viewmodel class for this type of thing:
public class IndexViewModel
{
public string LogoUrl { get; set; }
}
I use that viewmodel in the controller's action method like so.
public ActionResult Index()
{
var viewModel = new IndexViewModel();
viewModel.LogoUrl = // Get this from DB.
return View(viewModel);
}
Finally, I can use the LogoUrl in the view:
#using IndexViewModel
#Html.TextBoxFor(m => m.LogoUrl)
This way, you can display the LogoUrl when the page loads (note, you will likely have different action method named to Index, I was just making an assumption).

MVC4 model binding - Passing Custom View Models & values from view to controller

I have a strongly typed view with the following model.
public class ProductViewModel
{
public Product Product { get; set; }
public List<ProductOptionWithValues> ProductOptionsWithValues { get; set; }
}
public class ProductOptionWithValues
{
public ProductOption ProductOption;
public List<AllowedOptionValue> AllowedOptionValues;
}
I'm using this Model To populate a form where a user can select the options they want for a product.
This is the view.
#model AsoRock.Entities.ViewModels.ProductViewModel
#{
ViewBag.Title = "Details";
}
#using (Html.BeginForm(new { ReturnUrl = ViewBag.ReturnUrl }))
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
<h3>
#Html.DisplayFor(model => model.Product.ProductName)
----> #Html.DisplayFor(model => model.Product.Price)
</h3>
<br/>
foreach (var item in Model.ProductOptionsWithValues)
{
<b>#Html.DisplayFor(modelItem => item.ProductOption.Option.OptionName)</b>
<br/>
#Html.DropDownListFor(m => m.ProductOptionsWithValues,
new SelectList(item.AllowedOptionValues,
"Id", "DisplayString",
item.AllowedOptionValues.First().Id))
<br/>
}
<input type="submit" value="Add to cart" />
}
In my controller I am trying to pass the model back. When I set a break point in the controller it hits it but the Product view model is empty, any ideas how I can get the values that are selected in the view back in to my controller?
[HttpPost]
public ActionResult Details(ProductViewModel ProductViewModel)
{
return View();
//return View();
}

As mentioned in the comments, you need to change the name of the viewmodel parameter from ProductViewModel to something else e.g.
[HttpPost]
public ActionResult Details(ProductViewModel viewModel)
{
}
Now it's very odd that the viewModel param is not set to an instance of the class. The MVC model binder will still create an instance of ProductViewModel even if none of it's properties are set to anything. You're not using a custom model binder by any chance?
Also I would very strongly suggest that your viewmodel class does not have a Product property. Instead, create properties in the viewmodel specifically for the Product properties you intend to use e.g.
public class ProductViewModel
{
public string ProductName { get; set; }
public decimal ProductPrice { get; set; }
public List<ProductOptionWithValues> ProductOptionsWithValues { get; set; }
}
Using Product in the viewmodel sort of defeats the point of having a viewmodel. The viewmodel should contain only the bare minimum that the view needs. Including Product means the viewmodel is now bloated with extra data it does not use/need.
EDIT:
In your shoes, I would strip down the view itself, using only little bits of the viewmodel, and POST to the controller to see what happens. If the viewmodel calss is not NULL, go back to the view and add another bit back. Keep doing this until the viewmodel is NULL again. Doing this bit by bit should help.

How do I keep the clicked state of a checkbox in asp.net

I'm really having problems with keeping the state of my checkbox in my mvc4 application. I'm trying to send its value down to my controller logic, and refresh a list in my model based on the given value, before I send the model back up to the view with the new values. Given that my checkbox is a "show disabled elements in list" type function, I need it to be able to switch on and off. I've seen so many different solutions to this, but I can't seem to get them to work :(
Here's a part of my view:
#model MyProject.Models.HomeViewModel
<div class="row-fluid">
<div class="span12">
<div class="k-block">
<form action="~/Home/Index" name="refreshForm" method="POST">
<p>Include disabled units: #Html.CheckBoxFor(m => m.Refresh)</p>
<input type="submit" class="k-button" value="Refresh" />
#* KendoUI Grid code *#
</div>
</div>
HomeViewModel:
public class HomeViewModel
{
public List<UnitService.UnitType> UnitTypes { get; set; }
public bool Refresh { get; set; }
}
The HomeViewController will need some refactoring, but that will be a new task
[HttpPost]
public ActionResult Index(FormCollection formCollection, HomeViewModel model)
{
bool showDisabled = model.Refresh;
FilteredList = new List<UnitType>();
Model = new HomeViewModel();
var client = new UnitServiceClient();
var listOfUnitsFromService = client.GetListOfUnits(showDisabled);
if (!showDisabled)
{
FilteredList = listOfUnitsFromService.Where(unit => !unit.Disabled).ToList();
Model.UnitTypes = FilteredList;
return View(Model);
}
FilteredList = listOfUnitsFromService.ToList();
Model.UnitTypes = FilteredList;
return View(Model);
}

You return your Model to your view, so your Model properties will be populated, but your checkbox value is not part of your model! The solution is to do away with the FormCollection entirely and add the checkbox to your view model:
public class HomeViewModel
{
... // HomeViewModel's current properties go here
public bool Refresh { get; set; }
}
In your view:
#Html.CheckBoxFor(m => m.Refresh)
In your controller:
[HttpPost]
public ActionResult Index(HomeViewModel model)
{
/* Some logic here about model.Refresh */
return View(model);
}
As an aside, I can't see any reason why you'd want to add this value to the session as you do now (unless there's something that isn't evident in the code you've posted.

How to use multiple form elements in ASP.NET MVC

So I am new to ASP.NET MVC and I would like to create a view with a text box for each item in a collection. How do I do this, and how do I capture the information when it POSTs back? I have used forms and form elements to build static forms for a model, but never dynamically generated form elements based on a variable size collection.
I want to do something like this in mvc 3:
#foreach (Guest guest in Model.Guests)
{
<div>
First Name:<br />
#Html.TextBoxFor(???) #* I can't do x => x.FirstName here because
the model is of custom type Invite, and the
lambda wants to expose properties for that
type, and not the Guest in the foreach loop. *#
</div>
}
How do I do a text box for each guest? And how do I capture them in the action method that it posts back to?
Thanks for any help.

Definitely a job for an editor template. So in your view you put this single line:
#Html.EditorFor(x => x.Guests)
and inside the corresponding editor template (~/Views/Shared/EditorTemplates/Guest.cshtml)
#model AppName.Models.Guest
<div>
First Name:<br />
#Html.TextBoxFor(x => x.FirstName)
</div>
And that's about all.
Now the following actions will work out of the box:
public ActionResult Index(int id)
{
SomeViewModel model = ...
return View(model);
}
[HttpPost]
public ActionResult Index(SomeViewModel model)
{
if (!ModelState.IsValid)
{
return View(model);
}
// TODO: do something with the model your got from the view
return RedirectToAction("Success");
}
Note that the name of the editor template is important. If the property in your view model is:
public IEnumerable<Guest> Guests { get; set; }
the editor template should be called Guest.cshtml. It will automatically be invoked for each element of the Guests collection and it will take care of properly generating ids and names of your inputs so that when you POST back everything works automatically.
Conclusion: everytime you write a loop (for or foreach) inside an ASP.NET MVC view you should know that you are doing it wrong and that there is a better way.

You can do this:
#for (int i = 0; i < Model.Guests.Count; i++) {
#Html.TextBoxFor(m => m.Guests.ToList()[i].FirstName)
}
There are more examples and details on this post by Haacked.
UPDATE: The controller post action should look like this:
[HttpPost]
public ActionResult Index(Room room)
{
return View();
}
In this example I'm considering that you have a Room class like this:
public class Room
{
public List<Guest> Guests { get; set; }
}
That's all, on the post action, you should have the Guests list correctly populated.