In my models I have a BIGINT (long/int64) foreign key reference to LookupCategory. In the View, I have a DropDownListFor as follows:
#Html.DropDownListFor(model => model.LookupKey.LookupCategory, new SelectList(Model.LookupCategories, "ID", "Name"))
The create/edit views display fine, but upon selecting an item submitting the ModelBinder complains "The value '1' is invalid." because it is reading it in as a string rather than a long.
Is there a way to fix this without touching the model? I'd prefer not to implement ModelBinder just to solve this little issue, but if I must, I've got this drafted:
public class LookupKeyBinder : DefaultModelBinder
{
protected override void BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext,
System.ComponentModel.PropertyDescriptor propertyDescriptor)
{
base.BindProperty(controllerContext, bindingContext, propertyDescriptor);
if (propertyDescriptor.PropertyType == typeof(LookupKey))
{
var modelState = bindingContext.ModelState[string.Format("{0}.{1}", propertyDescriptor.Name, "LookupCategory")];
propertyDescriptor.SetValue(bindingContext.Model, long.Parse(modelState.Value.AttemptedValue));
modelState.Errors.Clear();
return;
}
}
}
It's arranged like that because I want access to the ModelState, not have to know the form field names (which could change between views). So I get the long value properly, but the problem is that the DefaultModelBinder already did its work and instead of long, I need the actual LookupCategory (whose ID is the long value). I can't figure out how to use the default model binder again to use its default behavior for finding the LookupCategory from the database. Anyway, this is a lot of trickery for something that seems like it should be simple!
As I suspected, examining the model and LookupKey classes helped resolve the issue. I have had several experiences like that, where a second look at the class showed I was not using the correct model property.
When you changed your DropDownListFor to use model.LookupKey.LookupCategory.ID, that synced up with the correct property, and viola!
Congrats on spotting the problem.
Related
I have a view model sent to the edit action of my controller. The ViewModel contains references to EntityObjects. (yea i'm fine with it and don't need to want to duplicate all the entities properties in the viewmodel).
I instantiate the view model and then call UpdateModel. I get an error that a property is "null" which is fine since it is a related model. I am trying to exclude the property from being bound during model binding. On debugging it I see in the entity where the model binder is trying to set the value of the property to null.
Here is my edit action:
var model = new SimplifiedCompanyViewModel(id);
var excludeProperties = new string[] {
"Entity.RetainedEarningsAccount.AccountNo"
,"Property.DiscountEarnedAccount.ExpenseCodeValue"
,"Entity.EntityAlternate.EntityID"
,"Property.BankAccount.BankAccountID"
,"Entity.PLSummaryAccount.AccountNo"
,"Property.RefundBank.BankAccountID"
,"Company.Transmitter.TCC"
};
try
{
UpdateModel<SimplifiedCompanyViewModel>(model, String.Empty, null, excludeProperties);
if (ModelState.IsValid)
{
//db.SaveChanges();
}
return RedirectToAction("Index");
}
catch
{
return View(model);
}
I have looked at a few other issues about specifying a "prefix" but I don't think that is the issue since I am telling it to bind to the viewmodel instance not just the entity object.
Am I excluding the properties correctly? Strange thing is is only seems to happen on this item. I suspect it may be an issue with the fact that there is actually no refund bank related to my entity. But I have other related items that don't exist and don't see the same issue.
More info... since I'm told me model isn't designed well.
The Company is related to a BankAccount. The Company view shows the currently related BankAccount.BankAccountId and there is a hidden field with the BankAccount.Key. I use jQueryUI autocomplete feature to provide a dropdown of bank account displaying the BankAccount.BankAccountId and when one is selected the jQuery code changes the hidden field to have the correct Key value. So, when this is posted I don't want the current bankaccounts BankAccountID modified, hence I want it to skip binding that field.
If I exclude BankAccountId in the model then on the BankAccount edit view the user would never be able to change the BankAccountId since it won't be bound. I'm not sure how this indicates a poor model design.
Use the Exclude property of the Bind attribute:
[Bind(Exclude="Id,SomeOtherProperty")]
public class SimplifiedCompanyViewModel
{
public int Id { get; set; }
// ...
}
This is part of the System.Web.Mvc namespace. It takes a comma-separated list of property names to exclude when binding.
Also you should consider using TryUpdateModel instead of UpdateModel. You can also just have the default model binder figure it out by passing it as an argument to the constructor:
public ActionResult Create([Bind(Exclude="Id")]SimplifiedCompanyViewModel model)
{
// ...
}
A very simple solution that I figured out.
try
{
UpdateModel<SimplifiedCompanyViewModel>(model, String.Empty, null, excludeProperties);
ModelState.Remove("Entity.RetainedEarningsAccount.AccountNo");
ModelState.Remove("Property.DiscountEarnedAccount.ExpenseCodeValue");
ModelState.Remove("Entity.EntityAlternate.EntityID");
ModelState.Remove("Property.BankAccount.BankAccountID");
ModelState.Remove("Entity.PLSummaryAccount.AccountNo");
ModelState.Remove("Property.RefundBank.BankAccountID");
ModelState.Remove("ompany.Transmitter.TCC");
if (ModelState.IsValid)
{
//db.SaveChanges();
}
return RedirectToAction("Index");
}
catch
{
return View(model);
}
Another option here is simply don't include this attribute in your view and it won't be bound. Yes - you are still open to model injection then if someone creates it on the page but it is another alternative. The default templates in MVC will create your EditorFor, etc as separate items so you can just remove them. This prevents you from using a single line view editor with EditorForModel, but the templates don't generate it that way for you anyways.
EDIT (adding above comment)
DRY generally applies to logic, not to view models. One view = one view model. Use automapper to easily map between them. Jimmy Bogard has a great attribute for this that makes it almost automatic - ie you create the view model, load up your Customer entity for example, and return it in the action method. The AutpMap attribute will then convert it to a ViewModel. See lostechies.com/jimmybogard/2009/06/30/how-we-do-mvc-view-models
Try the Exclude attribute.
I admit that I haven't ever used it.
[Exclude]
public Entity Name {get; set;}
This is a follow on from the following question:
MVC 3 + $.ajax - response seems to be caching output from partial view
There is a detailed description of the problem over there. However, I have now managed to narrow down the problem, that seems to be with the Html.EditorFor helpers, hence the new question.
The issue:
I post data to the server using $.ajax, then return the html of the partial view that holds the input controls. The problem is that, despite passing a newly created object to the Partial Views model, the various #Html.EditorFor and #Html.DropDownListFor helpers return the OLD DATA!.
I can prove that the model has correctly passed in a new object to the helpers, by printing the value out beside the Html helper. Ie:
#Html.EditorFor(model => model.Transaction.TransactionDate)
#Model.Transaction.TransactionDate.ToString()
As the following image shows, the #Html.EditorFor is returning the wrong data:
[Note that the value beside the Comentario text box is a date time, because I was testing replacing the default values with a value that would change with each post, ie, a DateTime.]
If I replace the #Html.EditorFor for TransactionDate with a plain old #Html.TextBox():
#Html.TextBox("Transaction_TransactionDate", Model.Transaction.TransactionDate)
Then it renders the correct TransactionDate value for a new Transaction object, ie, DateTime.MinValue (01/01/0001...).
Therefore...
The problem is with the #Html.EditorFor helpers. The problem also happens with TextBoxFor and DropDownListFor.
The problem being that these helpers seem to cache the old value.
What am I doing wrong??!
EDIT:
I have just tried debugging in the custom Editor template for dates, and in there, ViewData.TemplateInfo.FormattedModelValue shows the correct value, ie, "01/01/0001". However, once it gets to Fiddler, the response is showing the old date, eg, "01/09/2011" in the image above.
As a result, I just think that there is some caching going on here, but I have none set up, so nothing makes any sense.
There is no caching involved here. It's just how HTML helper work. They first look at the ModelState when binding their values and then in the model. So if you intend to modify any of the POSTed values inside your controller action make sure you remove them from the model state first:
[HttpPost]
public virtual ActionResult AjaxCreate(Transaction transaction)
{
if (ModelState.IsValid)
{
service.InsertOrUpdate(transaction);
service.Save();
}
service.ChosenCostCentreId = transaction.IdCostCentre;
TransactionViewModel viewModel = new TransactionViewModel();
ModelState.Remove("Transaction");
viewModel.Transaction = new Transaction();
ModelState.Remove("CostCentre");
viewModel.CostCentre = service.ChosenCostCentre;
...
return PartialView("_Create", viewModel);
}
Even if you do not specify caching, it sometimes can occur. For my controllers which handle AJAX and JSON requests, I decorate them as follows:
[OutputCache(Location = OutputCacheLocation.None, NoStore = true)]
This specifically declares no caching should occur.
UPDATE
Based on an answer Darin Dimitrov gave here, try adding the following line to your controller action:
ModelState.Clear();
i have never seen this but basically if you are using ajax to request this data, you need to set nochache: i am assuming you using jQuery.ajax here so will show the code:
$.ajax({
url: "somecontroller/someAction,
cache: false, // this is key to make sure JQUERY does not cache your request
success: function( data ) {
alert( data );
}
});
just a stab in the dark, i assume you have probably already covered this already. have you tried to create a new model first and then populate that new instance of the model with your data, and then send this to your view!
Finally not sure what DB server your using but have you check to see that DB results are not cached and that you are not just requesting SQL results from the DB cache... i dont use MsSQL but i hear that it has outputCaching until something is change on the DB server itself?? anyway just a few thoughts
This was unexpected behavior for me, and although I understand the reason why it's necessary to give ModelState precedence, I needed a way to remove that entry so that the value from Model is used instead.
Here are a couple methods I came up with to assist with this. The RemoveStateFor method will take a ModelStateDictionary, a Model, and an expression for the desired property, and remove it.
HiddenForModel can be used in your View to create a hidden input field using only the value from the Model, by first removing its ModelState entry. (This could easily be expanded for the other helper extension methods).
/// <summary>
/// Returns a hidden input field for the specified property. The corresponding value will first be removed from
/// the ModelState to ensure that the current Model value is shown.
/// </summary>
public static MvcHtmlString HiddenForModel<TModel, TProperty>(this HtmlHelper<TModel> helper,
Expression<Func<TModel, TProperty>> expression)
{
RemoveStateFor(helper.ViewData.ModelState, helper.ViewData.Model, expression);
return helper.HiddenFor(expression);
}
/// <summary>
/// Removes the ModelState entry corresponding to the specified property on the model. Call this when changing
/// Model values on the server after a postback, to prevent ModelState entries from taking precedence.
/// </summary>
public static void RemoveStateFor<TModel, TProperty>(this ModelStateDictionary modelState, TModel model,
Expression<Func<TModel, TProperty>> expression)
{
var key = ExpressionHelper.GetExpressionText(expression);
modelState.Remove(key);
}
Call from a controller like this:
ModelState.RemoveStateFor(model, m => m.MySubProperty.MySubValue);
or from a view like this:
#Html.HiddenForModel(m => m.MySubProperty.MySubValue)
It uses System.Web.Mvc.ExpressionHelper to get the name of the ModelState property. This is especially useful when you have "Nested" models since the key name isn't obvious.
Make sure you're not doing this:
#Html.EditorFor(model => model.Transaction.TransactionDate.Date)
I did this, and the model never got the value back. It worked perfectly once I remove the .Date.
I'n new at this, so apologies if this isn't explanatory enough. I want to prepopulate a field in a form in asp.net mvc 3. This works;
#Html.TextBox("CompName", null, new { #value = ViewBag.CompName })
But when I want to prepopulate it with a value and send that value to my model, like this;
#Html.TextBoxFor(model => model.Comps.CompName, null, new { #value = ViewBag.CompName })
It won't work. Any ideas?
Thanks in advance!
So, I would suggest is to move to using viewmodels rather than the ViewBag. I made a folder in my project called ViewModels and then under there make some subfolders as appropriate where I put my various viewmodels.
If you create a viewmodel class like so:
public class MyViewModel
{
public string CompName { get; set; }
}
then in your controller action you can create one of those and populate it, maybe from some existing model pulled from a database. By setting that CompName property in the viewmodel, it'll have that value in your view. And then your view can look something like this:
#model MyNamespace.ViewModels.MyViewModel
#Html.EditorFor(model => model.CompName)
or #Html.TextBoxFor would work too.
Then back in your controller action on the post, you've got something like this:
[HttpPost]
public ActionResult MyAction(MyViewModel viewModel)
{
...
// do whatever you want with viewModel.CompName here, like persist it back
// to the DB
...
}
Might be that you use something like automapper to map your models and viewmodels but you could certainly do that manually as well, though the whole lefthand/righthand thing gets quite tedious.
Makes things much easier if you do it this way and isn't much work at all.
Update
But, if you really want to pass that value in view the ViewBag, you could do this:
In your controller action:
ViewBag.CompName = "Some Name";
Then in your view:
#Html.TextBoxFor(model =>model.Comps.CompName, new {#Value = ViewBag.CompName})
And that'll pre-populate the textbox with "Some Name".
I'd still go with the viewmodel approach, but this seems to work well enough. Hope that helps!
From your controller, if you pass a model initialized with default values using one of the View(...) method overloads that accepts a model object, these values will be used by the view when rendered. You won't need to use the #value = ... syntax.
I was researching something and came across this blog post at buildstarted.com about model binders. It actually works pretty darn well for my purposes but I am not sure exactly whats going on behind the scenes. What I did was create a custom ModelBinder called USerModelBinder:
public class UserModelBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
ValueProviderResult value = bindingContext.ValueProvider.GetValue("id");
MyEntities db = new MyEntities();
User user = db.Users.SingleOrDefault(u => u.UserName == value.AttemptedValue);
return user;
}
}
Then in my Global.asax.cs I have:
ModelBinders.Binders.Add(typeof(User), new UserModelBinder());
My understanding is that using the model binder allows me to NOT have to use the following lines in every controller action that involves a "User". So instead of passing in an "id" to the action, the modelbinder intercepts the id, fetches the correct "item"(User in my case) and forwards it to the action for processing.
MyEntities db = new MyEntities();
User user = db.Users.SingleOrDefault(u => u.UserName == value.AttemptedValue);
I also tried using an annotation on my User class instead of using the line in Global.asax.cs:
[ModelBinder(typeof(UserModelBinder))]
public partial class User
{
}
I'm not looking for a 30 page white paper but I have no idea how the model binder does what it does. I just want to understand what happens from when a request is made to the time it is served. All this stuff "just working" is not acceptable to me, lol. Also, is there any difference between using the annotation versus adding it in Global.asax.cs? They seem to work the same in my testing but are there any gotchas?
Usually the Model Binder (in MVC) looks at you Action method and sees what it requires (as in, the objects types). It then tries to find the values from the HTTP Request (values in the HTTP Form, QueryString, Json and maybe other places such as cookies etc. using ValueProviders). It then creates a new object with the parameters that it retrieves.
IMO What you've done is not really "model binding". In the sense that you've just read the id and fetched the object from the DB.
example of usual model binding:
// class
public class SomeClass
{
public int PropA {get;set;}
public string PropB {get;set;}
}
// action
public ActionResult AddSomeClass(SomeClass classToBind)
{
// implementation
}
// pseudo html
<form action="">
<input name="PropA" type="text" />
<input name="PropB" type="text" />
</form>
if you post a form that contains the correct values (lets say you post a form with PropA and PropB ) the model binder can identify that you've sent those values in the form and build a SomeClass object.
If you really want to create a real working example you should use a strongly typed View and use HtmlHelper's EditorFor (or EditorForModel) to create all the correct names that MVC needs.
--
for reference MVC's default binder is the DefaultModelBinder, and some (there are more, you can look around in the System.Web.Mvc namespace) ValueProviders that it uses by default are the FormValueProvider and the QueryStringValueProvider
So, as I already said, how this basically works is that the default model binder reads the model that the action is recieving (say SomeClass in the example) reads what are the values that it can read (say PropA and PropB) and asks the ValueProviders for the correct values for the properties.
Also, if I recall correctly, you can also see the value providers in runtime using the ValueProviderFactories static class.
A ModelBinder looks at the arguments of the selected Controller action's method signature, then converts the values from the ValueProviders into those arguments.
This happens when the ControllerActionInvoker invokes the action associated with the ControllerContext, because the Controller's Execute() method told it to.
For more about the ASP.NET MVC execution process, see Understanding the MVC Application Execution Process
I have an action method that takes in a string as its only parameter. The action method transforms it, and returns the result back to the client (this is done on an ajax call). I need to allow markup in the string value. In the past, I've done this by decorating the property on my model with [AllowHtml], but that attribute cannot be used on a parameter and the AllowHtmlAttribute class is sealed, so I cannot inherit from it. I currently have a work around where I've created a model with just one property and decorated it with the aforementioned attribute, and this is working.
I don't think I should have to jump through that hoop. Is there something I'm missing, or should I make a request to the MVC team to allow this attribute to be used on method parameters?
If you need to allow html input for a particular parameter (opposed to "model property") there's no built-in way to do that because [AllowHtml] only works with models. But you can easily achieve this using a custom model binder:
public ActionResult AddBlogPost(int id, [ModelBinder(typeof(AllowHtmlBinder))] string html)
{
//...
}
The AllowHtmlBinder code:
public class AllowHtmlBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
var request = controllerContext.HttpContext.Request;
var name = bindingContext.ModelName;
return request.Unvalidated[name]; //magic happens here
}
}
Find the complete source code and the explanation in my blog post: https://www.jitbit.com/alexblog/273-aspnet-mvc-allowing-html-for-particular-action-parameters/
Have you looked at ValidateInputAttribute? More info here: http://blogs.msdn.com/b/marcinon/archive/2010/11/09/mvc3-granular-request-validation-update.aspx.