I have that error
The ViewData item that has the key 'BookAttributesDDL' is of type 'System.String' but must be of type 'IEnumerable<SelectListItem>'.
in that code:
#Html.DropDownList("BookAttributesDDL", Model.BookAttributes_Items)
but the Model.BookAttributes_Items is type of the IEnumerable<SelectListItem> ! What's wrong ?
The ViewData.Keys property from the Immediate Window:
ViewData.Keys
Count = 2
[0]: "FCoookie"
[1]: "Title"
Try to avoid dynamic variables like ViewBag and ViewData. It will make your code unreadable and painful to maintain in future as it grows. ViewBag is like Magic strings !
Switch to the ViewModel approach.
Example, If you are creating a View to Create a Book, Create a Viewmodel (it is just a plain Class) for that like this
public class BookViewModel
{
public int BookId { set;get;}
public string BookName {set;get;}
public IEnumerable<SelectListItem> Attributes{ get; set; }
public int SelectedAttribute{ get; set; }
}
Now in your GET Action, Simply create an object of this class, Set the BookAttribbutes proeprties to your Dropdown items and pass this ViewModel object to the View
public ActionResult Create()
{
BookViewModel vm=new BookViewModel();
//The below code is hardcoded for demo. you mat replace with DB data.
vm.Attributes=new[]
{
new SelectListItem { Value = "1", Text = "F Cookie" },
new SelectListItem { Value = "2", Text = "Title" },
}
return View(vm);
}
Now in We will make our view strongly typed to this ViewModel class
#model BookViewModel
#using(Html.BeginForm())
{
#Html.TextBoxFor(x=>x.BookName)
#Html.DropDownListFor(x => x.SelectedAttribute,
new SelectList(Model.Attributes, "Value", "Text"), "Select Attribute")
<input type="submit" value="Save" />
}
Now you will get the Selected Dropdown value and the textbox value in your HttpPost action by accessing the corresponding properties of your ViewModel
[HttpPost]
public ActionResult Create(BookViewModel model)
{
if(ModelState.IsValid)
{
//check for model.BookName / model.SelectedAttribute
}
//validation failed.TO DO : reload dropdown here
return View(model);
}
Fully agree with View Model approach response to you (and its me who selected it as useful).
However, if you don't want to switch, but remain as is I bet your answer lays in this article.
Hope this help you.
Related
I'm working on the first MVC3 project at our company, and I've hit a block. No one can seem to figure out what's going on.
I have a complex Model that I'm using on the page:
public class SpaceModels : List<SpaceModel> {
public bool HideValidation { get; set; }
[Required(ErrorMessage=Utilities.EffectiveDate + Utilities.NotBlank)]
public DateTime EffectiveDate { get; set; }
public bool DisplayEffectiveDate { get; set; }
}
In the Controller, I create a SpaceModels object with blank SpaceModels for when Spaces get combined (this would be the destination Space).
// Need a list of the models for the View.
SpaceModels models = new SpaceModels();
models.EffectiveDate = DateTime.Now.Date;
models.DisplayEffectiveDate = true;
models.Add(new SpaceModel { StoreID = storeID, SiteID = siteID, IsActive = true });
return View("CombineSpaces", models);
Then in the View, I am using that SpaceModels object as the Model, and in the form making a TextBox for the Effective Date:
#model Data.SpaceModels
#using (Html.BeginForm("CombineSpaces", "Space")) {
<div class="EditLine">
<span class="EditLabel LongText">
New Space Open Date
</span>
#Html.TextBoxFor(m => m.EffectiveDate, new {
size = "20",
#class = "datecontrol",
// Make this as a nullable DateTime for Display purposes so we don't start the Calendar at 1/1/0000.
#Value = Utilities.ToStringOrDefault(Model.EffectiveDate == DateTime.MinValue ? null : (DateTime?)Model.EffectiveDate, "MM/dd/yyyy", string.Empty)
})
#Html.ValidationMessageFor(m => m.EffectiveDate)
</div>
<hr />
Html.RenderPartial("_SpaceEntry", Model);
}
The Partial View that gets rendered iterates through all SpaceModels, and creates a containing the Edit fields for the individual SpaceModel objects. (I'm using the List to use the same Views for when the Spaces get Subdivided as well.)
Then on the HttpPost, the EffectiveDate is still back at it's DateTime.MinValue default:
[HttpPost]
public ActionResult CombineSpaces(SpaceModels model, long siteID, long storeID, DateTime? effectiveDate) {
// processing code
}
I added that DateTime? effectiveDate parameter to prove that the value when it gets changed does in fact come back. I even tried moving the rendering of the TextBox into the _SpaceEntry Partial View, but nothing worked there either.
I did also try using the #Html.EditorFor(m => m.EffectiveDate) in place of the #Html.TextBoxFor(), but that still returned DateTime.MinValue. (My boss doesn't like giving up the control of rendering using the #Html.EditorForModel by the way.)
There has to be something simple that I'm missing. Please let me know if you need anything else.
Looking at the source code for DefaultModelBinder, specifically BindComplexModel(), if it detects a collection type it will bind the individual elements but will not attempt to bind properties of the list object itself.
What model binding does is attempt to match the names of things or elements in the view to properties in your model or parameters in your action method. You do not have to pass all of those parameters, all you have to do is add them to your view model, then call TryUpdateModel in your action method. I am not sure what you are trying to do with SpaceModel or List but I do not see the need to inherit from the List. Im sure you have a good reason for doing it. Here is how I would do it.
The view model
public class SpacesViewModel
{
public DateTime? EffectiveDate { get; set; }
public bool DisplayEffectiveDate { get; set; }
public List<SpaceModel> SpaceModels { get; set; }
}
The GET action method
[ActionName("_SpaceEntry")]
public PartialViewResult SpaceEntry()
{
var spaceModels = new List<SpaceModel>();
spaceModels.Add(
new SpaceModel { StoreID = storeID, SiteID = siteID, IsActive = true });
var spacesVm = new SpacesViewModel
{
EffectiveDate = DateTime.Now,
DisplayEffectiveDate = true,
SpaceModels = spaceModels
};
return PartialView("_SpaceEntry", spacesVm);
}
The POST action method
[HttpPost]
public ActionResult CombineSpaces()
{
var spacesVm = new SpacesViewModel();
// this forces model binding and calls ModelState.IsValid
// and returns true if the model is Valid
if (TryUpdateModel(spacesVm))
{
// process your data here
}
return RedirectToAction("Index", "Home");
}
And the view
<label>Effective date: </label>
#Html.TextBox("EffectiveDate", Model.EffectiveDate.HasValue ?
Model.EffectiveDate.Value.ToString("MM/dd/yyyy") : string.empty,
new { #class = "datecontrol" })
Sometimes you need to explicitly bind form data using hidden fields such as
#Html.HiddenField("EffectiveDate", Model.EfectiveDate.)
In order to bind the properties of the SpaceModel object you can add individual properties such as SiteID to the view model or add a SpaceModel property for a single SpaceModel. If you want to successfully bind a complex model, add it as a Dictionary populated with key-value pairs rather than a List. You should then add the dictionary to the view model. You can even add a dictionary of dictionaries for hierarchical data.
I hope this helps :)
I had a look at this:
ASP.NET MVC - How to pass an Array to the view?
and am struggeling with deploying my DateTime[] as a dropdownlist in the view, herewith my line but it is not correct:
<p style="color:Red"><%: Html.DropDownList("Choose a Sunday: ", (IEnumerable<SelectListItem>)ViewData["Sundays"], "--Select--")%>
</p>
In the controller i have:
[HttpGet]
public ActionResult MyAction()
{
DateTime[] allSundaysInMonth = GetDatesOfSundays(System.DateTime.Now);
ViewData["Sundays"] = allSundaysInMonth;
return View();
}
can someone help please?
thanks
Perhaps what you want to do is this:
[HttpGet]
public ActionResult MyAction()
{
IEnumerable<SelectListItem> allSundaysInMonth = GetDatesOfSundays(System.DateTime.Now).Select(day => new SelectListItem() { Text = day.ToString(), Value = day.ToString() });
ViewData["Sundays"] = allSundaysInMonth;
return View();
}
That is depending on your display format. What I'm trying to point out is that DateTime and SelectListItem may not have an implicit cast, so you get a type mismatch at runtime.
If you ever think (realize) dynamic magic variables like ViewData/ ViewBag is an evil and thinking about using strongly typed ViewModel for your view, you can do like this
create a ViewModel specific for your View (UI).
public class EventViewModel
{
public IEnumerable<SelectListItem> AllSundays { set;get;}
public string SelectedSunday { set;get;}
}
In your action method, set the value and send it to the view
public ActionResult MyAction()
{
var vm=new EventViewModel();
vm.AllSundays = GetDatesOfSundays(System.DateTime.Now).
Select(d => new SelectListItem() {
Text = d.ToString(), Value = d.ToString() }).ToList();
return View(vm);
}
Change your view like this
#model EventViewModel
#Html.DropDownListFor(x => x.SelectedSunday, Model.AllSundays, "--Select One--")
ViewBag/ViewData is bad. It makes your code ugly. Stick to strongly typed.
You cast the list to IEnumerable<SelectListItem>, but its a list of DateTimes. Casting the list to IEnumerable<DateTime> should fix it.
Or you might want to put list of SelectListItem on the ViewData instead!
I am trying to work out the best way of using a viewmodel in the case of creating a new object.
I have a very simple view model that contains a contact object and a select list of companies.
private ICompanyService _Service;
public SelectList ContactCompanyList { get; private set; }
public Contact contact { get; private set; }
public ContactCompanyViewModel(Contact _Contact)
{
_Service = new CompanyService();
contact = _Contact;
ContactCompanyList = GetCompanyList();
}
private SelectList GetCompanyList()
{
IEnumerable<Company> _CompanyList = _Service.GetAll();
return new SelectList(_CompanyList, "id", "name");
}
I then have contact controller that uses this viewmodel and enable me to select a related company for my contact.
[Authorize]
public ActionResult Create()
{
return View(new ContactCompanyViewModel(new Contact()));
}
My issue is with the create method on the controller.
[Authorize]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(Contact _Contact)
{
try
{
_Service.Save(_Contact);
return RedirectToAction("Index");
}
catch
{
return View();
}
}
The problem is that the view returns an empty contact object, but! the company id is populated, this is because the dropdown list explicitly declares its field name.
#Html.DropDownList("parent_company_id",Model.ContactCompanyList)
The standard html form fields pass the objects values back in the format of contact.forename when using the HTML.EditorFor helper...
#Html.EditorFor(model => model.contact.forename)
I can access them if I use a FormCollection as my create action method paremeter and then explicitly search for contact.value but I cannot use a Contact object as a parameter to keep my code nice and clean and not have to build a new contact object each time.
I tried passing the actual view model object back as a parameter but that simply blows up with a constructor error (Which is confusing seeing as the view is bound to the view model not the contact object).
Is there a way that I can define the name of the Html.EditFor field so that the value maps correctly back to the contact object when passed back to the create action method on my controller? Or Have I made some FUBAR mistake somewhere (that is the most likely explanation seeing as this is a learning exercise!).
Your view model seems wrong. View models should not reference any services. View models should not reference any domain models. View models should have parameterless constructors so that they could be used as POST action parameters.
So here's a more realistic view model for your scenario:
public class ContactCompanyViewModel
{
public string SelectedCompanyId { get; set; }
public IEnumerable<SelectListItem> CompanyList { get; set; }
... other properties that the view requires
}
and then you could have a GET action that will prepare and populate this view model:
public ActionResult Create()
{
var model = new ContactCompanyViewModel();
model.CompanyList = _Service.GetAll().ToList().Select(x => new SelectListItem
{
Value = x.id.ToString(),
Text = x.name
});
return View(model);
}
and a POST action:
[HttpPost]
public ActionResult Create(ContactCompanyViewModel model)
{
try
{
// TODO: to avoid this manual mapping you could use a mapper tool
// such as AutoMapper
var contact = new Contact
{
... map the contact domain model properties from the view model
};
_Service.Save(contact);
return RedirectToAction("Index");
}
catch
{
model.CompanyList = _Service.GetAll().ToList().Select(x => new SelectListItem
{
Value = x.id.ToString(),
Text = x.name
});
return View(model);
}
}
and now in your view you work with your view model:
#model ContactCompanyViewModel
#using (Html.BeginForm())
{
#Html.DropDownListFor(x => x.SelectedCompanyId, Model.CompanyList)
... other input fields for other properties
<button type="submit">Create</button>
}
This page works in two steps,
Step 1 - The user hits Index() and the SelectList is populated with the applications from the databse.
Step 2 - they select an applicaiton from the list, which posts the page back, which reloads the page with the application Details added
Error: When I run this and get to step 2, I get an error back saying:
The ViewData item that has the key 'ApplicationId' is of type 'System.Int32' but must be of type 'IEnumerable'.
This appears to be because the Model.ApplicationList is now null as it hasn't bound back to the model when the form was posted, can I make it do this?
View:
#using (Html.BeginForm())
{
#Html.DropDownListFor(x => x.ApplicationId, Model.ApplicationList, "Select an Application" , new { #onchange = "this.form.submit();" })
}
Model:
public class IndexModel
{
public int ApplicationId { get; set; }
public List<SelectListItem> ApplicationList { get; set; }
public string Detail { get; set}
}
Controller:
public ActionResult Index()
{
using (var dc = new Entities())
{
var model = new IndexModel();
model.ApplicationList = new List<SelectListItem>();
var applications = dc.Applications.OrderBy(a => a.Name).ToList();
foreach (var application in applications)
{
model.ApplicationList.Add(new SelectListItem
{
Selected = false,
Text = application.Name,
Value = application.Id.ToString()
});
}
model.ApplicationId = 1;
return View(model);
}
}
[HttpPost]
public ActionResult Index(IndexModel model)
{
model.Detail = GetDetail(model.ApplicationId);
return View(model);
}
I was struggling with the same problem. It doesn't look like .net mvc3 lets you do this without the help of jquery. Drop down lists will get their selected item bound to the model when posting but not all the items in the combo box. You would have to rebuild it each time you pass the viewmodel back to the view.
Another way around losing the dropdown list is to use ajax.
I am using strongly typed views in an MVC3 web app. I've noticed that when a form is submitted, the ViewModel that is passed to the controller only has values for properties that have form elements associated with them. For instance, the example below shows a simple confirmation View with a checkbox and a phone number that the user must confirm before proceeding. When the form is submitted to the controller action, the UserConfirmed property contains a value, but the PhoneNumber property is null.
Is there any way for the ViewModel to retain all of its values or do I have to repopulate the ViewModel properties that do not have form elements associated with them?
The View
#model WebMeterReplacement.ViewModels.Appointment.ScheduleConfirmationViewModel
#using (Html.BeginForm()) {
#Html.ValidationSummary(false)
#Html.CheckBoxFor(model => model.UserConfirmed)
<span>Please confirm before proceeding</span>
<div>
Phone Number: #Model.PhoneNumber
</div>
<input type="submit" value="Confirm"/>
The Controller
[HttpPost]
public ActionResult ScheduleConfirmation(ScheduleConfirmationViewModel model)
{
if (model.UserConfirmed)
{
// add ViewModel data to repository
}
else
{
ModelState.AddModelError("ERROR", WebResources.strERROR_ConfirmSchedule);
}
return View(model);
}
Since your writing the phonenumber as output to the page it won't be automatically posted back (you've found out that part) What you can do is populate an hidden or read-only field with the phonenumber so that it will be posted back to your controller. An second option is to make a new call to your datasource and repopulate your object before saving it back to your datasource.
I generally POST back information like this in a hidden input. I personally use this heavily to pass data needed to return the user exactly where they where before pressing edit.
In your case it's as simple as
#model WebMeterReplacement.ViewModels.Appointment.ScheduleConfirmationViewModel
#using (Html.BeginForm()) {
#Html.ValidationSummary(false)
#Html.CheckBoxFor(model => model.UserConfirmed)
<span>Please confirm before proceeding</span>
<div>
#Html.HiddenFor(m => m.PhoneNumber)
Phone Number: #Model.PhoneNumber
</div>
<input type="submit" value="Confirm"/>
For future reference:
If your passing complex objects back you need one hidden field per attribute (Hiddenfor does NOT iterate)
View
WRONG
#Html.HiddenFor(m => m.PagingData)
RIGHT
#Html.HiddenFor(m => m.PagingData.Count)
#Html.HiddenFor(m => m.PagingData.Skip)
#Html.HiddenFor(m => m.PagingData.PageSize)
Action
public HomeController(AViewModel Model)
{
PagingData PagingData = Model.PagingData;
Skip = PagingData.Skip;
}
If your passing Arrays you can do it like this
View
#if (Model.HiddenFields != null)
{
foreach (string HiddenField in Model.HiddenFields)
{
#Html.Hidden("HiddenFields", HiddenField)
}
}
Action
public HomeController(AViewModel Model)
{
String[] HiddenFields = Model.HiddenFields;
}
Well, the form will only POST elements that you have created. As you found out, simply writing the phone number out to the page will not suffice. The model binder can only bind those properties which exist in the posted data.
Generally you have a couple of options here:
1) You can create Input elements for all of the properties in your model, using visible elements (like a textbox) for those properties you want to edit, and hidden elements which should be posted back but have no UI
2) Post back a partial representation of your model (as you are doing now), read the entity back in from it's data source (I assume you're using some kind of data source, EF maybe) and then alter the properties of that entity with the ones from your form.
Both scenarios are common but it really depends on the complexity of your model.
I know this thread is a bit old, but thought I'd resurrect it to get feed back on my solution to this.
I'm in a similar situation where my objects are passed to a view, and the view may only display part of that object for editing. Obviously, when the controller receives the model back from the default model binder, and values not posted back become null.. and saving this means that a DB value becomes null just because it wasn't displayed/returned from a view.
I didn't like the idea of creating a model for each view. I know it's probably the right way... but I was looking for a reusable pattern that can be implemented fairly quickly.
See the "MergeWith" method... as this would be used to take a copy of the object from the database and merge it with the one returned from the view (posted back)
namespace SIP.Models
{
[Table("agents")]
public class Agent
{
[Key]
public int id { get; set; }
[Searchable]
[DisplayName("Name")]
[Column("name")]
[Required]
[StringLength(50, MinimumLength = 4)]
public string AgentName { get; set; }
[Searchable]
[DisplayName("Address")]
[Column("address")]
[DataType(DataType.MultilineText)]
public string Address { get; set; }
[DisplayName("Region")]
[Searchable]
[Column("region")]
[StringLength(50, MinimumLength = 3)]
public string Region { get; set; }
[DisplayName("Phone")]
[Column("phone")]
[StringLength(50, MinimumLength = 4)]
public string Phone { get; set; }
[DisplayName("Fax")]
[Column("fax")]
[StringLength(50, MinimumLength = 4)]
public string Fax { get; set; }
[DisplayName("Email")]
[RegularExpression(#"(\S)+", ErrorMessage = "White space is not allowed")]
[Column("email")]
[StringLength(50, MinimumLength = 4)]
public string Email { get; set; }
[DisplayName("Notes")]
[Column("notes")]
[DataType(DataType.MultilineText)]
public string Notes{ get; set; }
[DisplayName("Active")]
[Column("active")]
public bool Active { get; set; }
public override string ToString()
{
return AgentName;
}
public bool MergeWith(Agent a, string[] fields)
{
try
{
foreach (PropertyInfo pi in this.GetType().GetProperties())
{
foreach (string f in fields)
{
if (pi.Name == f && pi.Name.ToLower() != "id")
{
var newVal = a.GetType().GetProperty(f).GetValue(a,null);
pi.SetValue(this, newVal, null);
}
}
}
}
catch (Exception ex)
{
return false;
//todo: Log output to file...
}
return true;
}
}
}
And to use this in the controller.. you'd have something like..
[HttpPost]
public ActionResult Edit(Agent agent)
{
if (ModelState.IsValid)
{
Agent ag = db.Agents.Where(a => a.id == agent.id).ToList<Agent>().First<Agent>();
ag.MergeWith(agent, Request.Params.AllKeys);
db.Entry(ag).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(agent);
}
This way, during post back, it takes the object from the database, and updates it with object from view... but only updates the values that were posted back.. So if you have a field like "address" or something that doesn't appear in the view.. it doesn't get touched during the update.
I've tested this so far and i works for my purposes, tho i welcome any feedback as I'm keen to see how others have overcome this situation. It's a first version and i'm sure it can be implemented better like through an extension method or something.. but for now the MergeWith can be copy/pasted to each model object.
Yes, Just place hidden fields in the form for those values which you are not using and want to return to server control.
Thanks