Develop Reference

ViewModel Properties in Query String are not bound when arriving at Controller

I'm working in an ASP.net MVC application, and I have a table of products as shown in the screenshot:
I would like the ability to filter that table of products, and I'd like the filtering to happen via the query string params (as a GET) so that the URL can be shared.
The ViewModel for the page is like this:
public class InventoryReportViewModel
{
public SearchViewModel Search { get; set; } // 2 string props [Type and Term]
public IEnumerable<ProductViewModel> Products { get; set; }
public PaginationViewModel Pagination { get; set; } // 3 int props [currentPage, recordsPerPage, totalRecords]
}
I'm using Razor helpers to draw the filter inputs, like this:
#Html.EditorFor(m => m.Search.Term, new { htmlAttributes = new { #class = "form-control" } })
And also I've set up my form to use GET like so:
#using (Html.BeginForm("Inventory", "Report", FormMethod.Get))
{
// form elements
}
My ReportController.cs has the following method that is relevant to my question here:
public ActionResult Inventory(string SearchTerm, string SearchType, int page = 1)
{
var viewModel = _reportService.GetProducts(page, SearchTerm, SearchType);
return View(viewModel);
}
When I pass a Search term, and click the Filter Results button, I do arrive at my Controller method above, but the SearchTerm and SearchType are null.
I know how to "hack" this to work, for example, if I do this:
<input type="text" name="SearchTerm" class="form-control"/>
Then the search term I input would be picked up by the Controller, but is there no other way?

since you already made a viewmodel for Search
public SearchViewModel Search { get; set; }
you just need to pass it to the controller like this
public ActionResult Inventory(SearchViewModel Search, int page = 1
{
var viewModel = _reportService.GetProducts(page, Search.Term, Search.Type);
return View(viewModel);
}
you were getting null because the textboxes were named as Search.Term that is why it was not matching the parameters.

The form should be post
#using (Html.BeginForm("Inventory", "Report", FormMethod.Post))
{
// form elements
}
This can also be cleaner:
#Html.EditorFor(m => m.Search.Term, new { htmlAttributes = new { #class = "form-control" } })
to
#Html.EditorFor(m => m.Search.Term, new { #class = "form-control" } )
Another question,
In the razor view, do you have a model specified on the first line?

Set selected index of dropdown to zero after form submit in ASP.NET MVC

I am bit to new asp.net mvc and using aps.net mvc 5. I have create the below dropdown using html helpers in aps.net mvc. When i submit(post back) the form i want to set the selected index to zero. Here i am using a optionLabel "--select--". I want to set the selected value to that one ("--select--") after post back. How to achieve this. Please help. Thank you.
#Html.DropDownListFor(model => model.TestCategory, new SelectList(#ViewBag.TestCategories, "value", "text"), "-- Select --", new { #class = "form-control input-sm"})
Controller Code
[HttpGet]
public ActionResult Index()
{
var model = new LaboratoryViewModel {
medicaltestlist = new List<MedicalTest>()
};
PopTestCategory();
PopEmptyDropdown();
return View(model);
}
[HttpPost]
public ActionResult Index(LaboratoryViewModel labvm)
{
var test = PopMedicalTests().Where(x => x.TestSerial == Convert.ToInt32(labvm.TestCode)).FirstOrDefault();
if (labvm.medicaltestlist == null)
labvm.medicaltestlist = new List<MedicalTest>();
if(!labvm.medicaltestlist.Any(x=> x.TestSerial == test.TestSerial))
labvm.medicaltestlist.Add(test);
labvm.TestCategory = "";
PopTestCategory();
return View(labvm);
}
public void PopTestCategory()
{
var categorylist = new List<DropDownItem>
{
new DropDownItem{value="Medical",text="Medical"},
new DropDownItem{value="Animal",text="Animal"},
new DropDownItem{value="Food",text="Food"},
new DropDownItem{value="Water",text="Water"}
};
ViewBag.TestCategories = categorylist;
}
public class DropDownItem
{
public int id { get; set; }
public string value { get; set; }
public string text { get; set; }
}

You return the view in you post method so if you selected (say) Animal then that value will be selected when you return the view because the html helpers use the values from ModelState, not the model property. Setting labvm.TestCategory = ""; has no effect. The correct approach is to follow the PRG pattern and redirect to the GET method, however you can make this work by calling ModelState.Clear(); before setting resetting the value of TestCategory although this will clear all ModelState properties and errors and may have other side effects.
Side note: You DropDownItem class seems unnecessary. MVC already has a SelectListItem class designed to work with dropdownlists, and in any case you can replace all the code in your PopEmptyDropdown() method with
ViewBag.TestCategories = new SelectList(new List<string>() { "Medical", "Animal", "Food", "Water" });
and in the view
#Html.DropDownListFor(m => m.TestCategory, (SelectList)#ViewBag.TestCategories, "-- Select --", new { #class = "form-control input-sm"})

If you set the "value" attribute of the top item in the drop down list to something and then pass back a model containing that for the bound property it should work?

All Dropdown Items have ZERO index MVC3

I have populated a dropdown list with values from Database Table. The list gets populated with correct table data but all values have ZERO index in the list. Here is the code to fill dropdown list:
//Get
public ActionResult NewBooking()
{
var db = new VirtualTicketsDBEntities2();
IEnumerable<SelectListItem> items = db.Attractions
.ToList()
.Select(c => new SelectListItem
{
Value = c.A_ID.ToString(),
Text = c.Name
});
ViewBag.Attractions = items;
return View();
}
And on Dropdown View Page:
<div class="editor-label">
#Html.LabelFor(model => model.Attraction)
</div>
<div class="editor-field">
#Html.DropDownList("Attractions")
</div>
For example if table have 3 values A,B, and C. These values are appearing in dropdown list but when I get its selected index in POST request function, it always returns ZERO. Here is the POST submit function:
//Post
[HttpPost]
public ActionResult NewBooking(BookingView booking)
{
try
{
BookingManager bookingManagerObj = new BookingManager();
bookingManagerObj.Add(booking);
ViewBag.BookingSavedSucess = "Booking saved!";
return View("WelcomeConsumer","Home");
}
catch
{
return View(booking);
}
}
booking.Attraction is always ZERO even user selected greater than ZERO index item.
Any suggestions?

I would guess that it is because you are getting a collection of SelectListItems back and not an actual SelectList. Try something like:
<div class="editor-field">
#Html.DropDownListFor(model => model.Attraction, new SelectList(ViewBag.Attractions, "Value", "Text");

It's best not to use ViewBag, you should always use a ViewModel.
Say you have a ViewModel like this:
public class AttractionViewModel
{
public int AttractionId { get; set; }
public SelectList Attractions { get; set; }
}
and modify your view like this - I presume you already have a form in there, the relevant bit is the #Html.DropDownListFor(...) and making sure you have the full namespace to the ViewModel if you haven't already included it in the Views web.config file:
#model AttractionViewModel
#using(Html.BeginForm("NewBooking", "ControllerName"))
{
<div class="editor-label">
#Html.LabelFor(model => model.AttractionId)
</div>
<div class="editor-field">
#Html.DropDownListFor(model => model.AttractionId, Model.Attractions)
</div>
<input type="submit" value="Submit">
}
and modify your HttpGet like this:
//Get
public ActionResult NewBooking()
{
var db = new VirtualTicketsDBEntities2();
var items = db.Attractions.ToList();
var attractionIdDefault = 0;// default value if you have one
var vm = new AttractionViewModel {
AttractionId = attractionIdDefault,// set this if you have a default value
Attractions = new SelectList(items, "A_ID", "Name", attractionIdDefault)
}
return View(vm);
}
and create an HttpPost ActionResult like this:
// Post
public ActionResult NewBooking(AttractionViewModel vm)
{
var attractionId = vm.AttractionId; // You have passed back your selected attraction Id.
return View();
}
Then it should work.

I know that you have already selected your answer but here is an alternative way of doing what you did. When I started off with ASP.NET MVC I struggled with SelectListItem and found another way of populating my drop down list. I have stuck to this way ever since.
I always have a view model that I bind to my view. I never send through a domain model, always a view model. A view model is just a scaled down version of your domain model and can contain data from multiple domain models.
I have made some modifications to your code and tips, but like I mentioned, it's just an alternative to what you already have.
Your domain model could look like this. Try and give your property names some meaningful descriptions:
public class Attraction
{
public int Id { get; set; }
public string Name { get; set; }
}
You view model could look something like this:
public class BookingViewModel
{
public int AttractionId { get; set; }
public IEnumerable<Attraction> Attractions { get; set; }
// Add your other properties here
}
Do not have your data access methods in your controllers, rather have a service layer or repository expose this functionality:
public class BookingController : Controller
{
private readonly IAttractionRepository attractionRepository;
public BookingController(IAttractionRepository attractionRepository)
{
this.attractionRepository = attractionRepository;
}
public ActionResult NewBooking()
{
BookingViewModel viewModel = new BookingViewModel
{
Attractions = attractionRepository.GetAll()
};
return View(viewModel);
}
[HttpPost]
public ActionResult NewBooking(BookingViewModel viewModel)
{
// Check for null viewModel
if (!ModelState.IsValid)
{
viewModel.Attractions = attractionRepository.GetAll();
return View(viewModel);
}
// Do whatever else you need to do here
}
}
And then your view will populate your drop down like this:
#model YourProject.ViewModels.Attractionss.BookingViewModel
#Html.DropDownListFor(
x => x.AttractionId,
new SelectList(Model.Attractions, "Id", "Name", Model.AttractionId),
"-- Select --"
)
#Html.ValidationMessageFor(x => x.AttractionId)
I hope this helps.

Tag Model in a mvc form [duplicate]

This question already has answers here:
NullReferenceException after POST
(2 answers)
Closed 9 years ago.
I've got a form that has a dropDownlist using the Model to fill the list, the view is rendered. The issue is that when i press the submit button, a null pointer exception for Model is thrown. I want to receive the value selected in the Post Action.
Here is my code:
Model:
public class BillViewModel
{
public List<SelectListItem> ClientList { get; set; }
public int SelectedClient { get; set; }
}
Controller:
public ActionResult Index()
{
var billRepo = new BillRepo();
var bill = new BillViewModel {ListProducts = billRepo.GetAllProducts()};
bill.ClientList = new List<SelectListItem>();
List<Client> allClientList = billRepo.GetAllClients();
foreach (Client client in allClientList)
{
var item = new SelectListItem() { Value = client.ClientId.ToString(), Text = client.Name };
bill.ClientList.Add(item);
}
ViewBag.ClientSelect = new SelectList(billRepo.GetAllClients(), "value", "text", bill.SelectedClient);
bill.SelectedClient = 1;
return View(bill);
}
[HttpPost]
public ActionResult Index(BillViewModel billViewModel)
{
return View();
}
View: The Model
#using (Html.BeginForm())
{
#Html.DropDownListFor(item => item.SelectedClient, Model.ClientList, "Select Client")
<input type="submit" value="Aceptar"/>
}

In your POST action you are returning the same Index view as in your GET action. But you are not passing any model to this view. That's why you are getting a NRE. Your view must render a dropdown and you need to populate its values, the same way you did in your GET action:
[HttpPost]
public ActionResult Index(BillViewModel billViewModel)
{
bill.ClientList = billRepo
.GetAllClients()
.ToList()
.Select(x => new SelectListItem
{
Value = client.ClientId.ToString(),
Text = client.Name
})
.ToList();
return View(billViewModel);
}
Notice how the view model is passed to the view and how the ClientList property (to which your dropdown is bound) is filed with values.

How simplify my request code?

I use this part of code to get informations from my database, using Entity Framework, and add all of it in a IEnumerable property for, at the end, a DropDownListFor display.
I need to use that kind a code many time so I would like to make it the most powerfull at the begenning.
public IEnumerable<SelectListItem> Functions { get
{
List<SelectListItem> result = new List<SelectListItem>();
using (followupconsultantEntities dataModel = new followupconsultantEntities())
{
var myEvents = from e in dataModel.functions
select e;
foreach (var function in myEvents)
{
SelectListItem myList = new SelectListItem
{
Value = function.ID_Function.ToString(CultureInfo.InvariantCulture),
Text = function.FU_Name
};
result.Add(myList);
}
}
return result;
} }
Thanks for help
The view:
<div class="editor-field">
<%: Html.DropDownListFor(m => m.SelectedFunction,Model.Functions) %>
</div>
For information, my controller:
public ActionResult Register()
{
ViewData["PasswordLength"] = MembershipService.MinPasswordLength;
return View(new RegisterModel());
}

Start using System.Web.Mvc.SelectList.
public IEnumerable<SelectListItem> Functions { get
{
using (followupconsultantEntities dataModel = new followupconsultantEntities())
{
return new SelectList(dataModel.functions.ToArray(), "ID_Function", "FU_Name");
}
}
Also consider AutoMapper.

Try this. In this code you will not get from database data that you not need.
public IEnumerable<SelectListItem> Functions { get
{
using (followupconsultantEntities dataModel = new followupconsultantEntities())
{
return new SelectList(dataModel.functions.Select(f=>
new
{
Value = function.ID_Function.ToString(CultureInfo.InvariantCulture),
Text = function.FU_Name
})
.ToArray(), "Value", "Text");
}
}