I cannot come up with a solution to a problem that's best described verbally and with a little code. I am using VS 2013, MVC 5, and EF6 code-first; I am also using the MvcControllerWithContext scaffold, which generates a controller and views that support CRUD operations.
Simply, I have a simple model that contains a CreatedDate value:
public class WarrantyModel
{
[Key]
public int Id { get; set; }
public string Description { get; set; }
DateTime CreatedDate { get; set; }
DateTime LastModifiedDate { get; set; }
}
The included MVC scaffold uses the same model for its index, create, delete, details, and edit views. I want the CreatedDate in the 'create' view; I do not want it in the 'edit' view because I do not want its value to change when the edit view is posted back to the server and I don't want anyone to be able to tamper with the value during a form-post.
Ideally, I don't want the CreatedDate to ever get to the Edit view. I have found a few attributes I can place on the model's CreatedDate property (for example, [ScaffoldColumn(false)]) that prevent it from appearing on the Edit view, but then I'm getting binding errors on postback because the CreatedDate ends up with a value of 1/1/0001 12:00:00 AM. That's because the Edit view is not passing a value back to the controller for the CreatedDate field.
I don't want to implement a solution that requires any SQL Server changes, such as adding a trigger on the table that holds the CreatedDate value. If I wanted to do a quick-fix, I would store the CreatedDate (server-side, of course) before the Edit view is presented and then restore the CreatedDate on postback--that would let me change the 1/1/0001 date to the CreatedDate EF6 pulled from the database before rendering the view. That way, I could send CreatedDate as a hidden form field and then overwrite its value in the controller after postback, but I don't have a good strategy for storing server-side values (I don't want to use Session variable or the ViewBag).
I looked at using [Bind(Exclude="CreatedDate")], but that doesn't help.
The code in my controller's Edit post-back function looks like this:
public ActionResult Edit([Bind(Include="Id,Description,CreatedDate,LastModifiedDate")] WarrantyModel warrantymodel)
{
if (ModelState.IsValid)
{
db.Entry(warrantymodel).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(warrantymodel);
}
I thought I might be able to examine the db.Entry(warrantymodel) object within the if block above and examine at the OriginalValue for CreatedDate, but when I try to access that value (as shown next), I get an exception of type 'System.InvalidOperationException':
var originalCreatedDate = db.Entry(warrantymodel).Property("CreatedDate").OriginalValue;
If I could successfully examine the original CreatedDate value (i.e., the one that is already in the database) I could just overwrite whatever the CurrentValue is. But since the above line of code generates an exception, I don't know what else to do. (I thought about querying the database for the value but that's just silly since the database was already queried for the value before the Edit view was rendered).
Another idea I had was to change the IsModified value to false for the CreatedDate value but when I debug then I discover that it is already is set to false in my 'if' block shown earlier:
bool createdDateIsModified = db.Entry(warrantymodel).Property("CreatedDate").IsModified;
I am out of ideas on how to handle this seemingly simple problem. In summary, I do not want to pass a model field to an Edit view and I want that field (CreatedDate, in this example) to maintain its original value when the other Edit fields from the view are posted back and persisted to the database using db.SaveChanges().
Any help/thoughts would be most appreciated.
Thank you.
You should leverage ViewModels:
public class WarrantyModelCreateViewModel
{
public int Id { get; set; }
public string Description { get; set; }
DateTime CreatedDate { get; set; }
DateTime LastModifiedDate { get; set; }
}
public class WarrantyModelEditViewModel
{
public int Id { get; set; }
public string Description { get; set; }
DateTime LastModifiedDate { get; set; }
}
The intention of a ViewModel is a bit different than that of a domain model. It provides the view with just enough information it needs to render properly.
ViewModels can also retain information that doesn't pertain to your domain at all. It could hold a reference to the sorting property on a table, or a search filter. Those certainly wouldn't make sense to put on your domain model!
Now, in your controllers, you map properties from the ViewModels to your domain models and persist your changes:
public ActionResult Edit(WarrantyModelEditViewModel vm)
{
if (ModelState.IsValid)
{
var warrant = db.Warranties.Find(vm.Id);
warrant.Description = vm.Description;
warrant.LastModifiedDate = vm.LastModifiedDate;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(warrantymodel);
}
Furthermore, ViewModels are great for amalgamating data from multiple models. What if you had a details view for your warranties, but you also wanted to see all servicing done under that warranty? You could simply use a ViewModel like this:
public class WarrantyModelDetailsViewModel
{
public int Id { get; set; }
public string Description { get; set; }
DateTime CreatedDate { get; set; }
DateTime LastModifiedDate { get; set; }
List<Services> Services { get; set; }
}
ViewModels are simple, flexible, and very popular to use. Here is a good explantion of them: http://lostechies.com/jimmybogard/2009/06/30/how-we-do-mvc-view-models/
You're going to end up writing a lot of mapping code. Automapper is awesome and will do most of the heavy lifting: http://automapper.codeplex.com/
This is not an answer for the questions, but it might be critical for those who is using Bind() and facing different problems. When I was searching "why Bind() clears out all pre-existing but not-bound values", I found this:
(in the HttpPost Edit()) The scaffolder generated a Bind attribute and added the entity created by the model binder to the entity set with a Modified flag. That code is no longer recommended because the Bind attribute clears out any pre-existing data in fields not listed in the Include parameter. In the future, the MVC controller scaffolder will be updated so that it doesn't generate Bind attributes for Edit methods.
from a official page (last updated in 2015, March):
http://www.asp.net/mvc/overview/getting-started/getting-started-with-ef-using-mvc/implementing-basic-crud-functionality-with-the-entity-framework-in-asp-net-mvc-application#overpost
According to the topic:
Bind is not recommended and will be removed in the future from the auto-generated codes.
TryUpdateModel() is now the official solution.
You can search "TryUpdateModel" in the topic for details.
It may solve your problem
In Model:
Use ?
public class WarrantyModel
{
[Key]
public int Id { get; set; }
public string Description { get; set; }
DateTime? CreatedDate { get; set; }
DateTime? LastModifiedDate { get; set; }
}
After form submit:
public ActionResult Edit([Bind(Include = "Id,Description,CreatedDate,LastModifiedDate")] WarrantyModel warrantymodel)
{
if (ModelState.IsValid)
{
db.Entry(warrantymodel).State = EntityState.Modified;
db.Entry(warrantymodel).Property("CreatedDate").IsModified=false
db.SaveChanges();
return RedirectToAction("Index");
}
return View(warrantymodel);
}
+1 for cheny's answer. Use TryUpdateModel instead of Bind.
public ActionResult Edit(int id)
{
var warrantymodel = db.Warranties.Find(id);
if (TryUpdateModel(warrantymodel, "", new string[] { "Id", "Description", "LastModifiedDate" }))
{
db.SaveChanges();
return RedirectToAction("Index");
}
return View(warrantymodel);
}
If you want to use View Model, you can use Automapper and configure it to skip null values so the existing data still exists in the domain model.
Example:
Model:
public class WarrantyModel
{
public int Id { get; set; }
public string Description { get; set; }
DateTime CreatedDate { get; set; }
DateTime? LastModifiedDate { get; set; }
}
ViewModel:
public class WarrantyViewModel
{
public int Id { get; set; }
public string Description { get; set; }
DateTime? CreatedDate { get; set; }
DateTime? LastModifiedDate { get; set; }
}
Controller:
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include="Id,Description,LastModifiedDate")] WarrantyViewModel warrantyViewModel)
{
var warrantyModel = db.Warranties.Find(warrantyViewModel.Id);
Mapper.Map(warrantyViewModel, warrantyModel);
if (ModelState.IsValid)
{
db.Entry(warrantyModel).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(warrantyModel);
}
Automapper:
Mapper.CreateMap<WarrantyViewModel, WarrantyModel>()
.ForAllMembers(opt => opt.Condition(srs => !srs.IsSourceValueNull));
try to remove the Create date prompt text box in the Edit view. In my application, the scaffold generated Edit and Create Views contain the Primary key which is generated in the database.
Controller:
...
warrantymodel.CreatedDate = DateTime.Parse(Request.Form["CreatedDate"]);
...
Related
I try to add a new Country which has a link to continent. When I press the "Create" button, it doesn't add a new record. I debugged my project and I think it's because the ValidState is false. The reason because of this is that the property "Continent" is null, but the Continent_Id isn't.
I have the same problem when I try to edit an existing Country. (I have populated my database with an SQL script in SQL Management Studio)
Can someone help me please?
Continent class:
public class Continent
{
public int Id { get; set; }
[Required, MaxLength(25)]
public string Name { get; set; }
//Navigation
public virtual List<Country> Countries { get; set; }
}
Country class
public class Country
{
public int Id { get; set; }
[Required, MaxLength(25)]
public string Name { get; set; }
[MaxLength(5)]
public string Abbreviation { get; set; }
public int Continent_Id { get; set; }
//Navigation
[Required, ForeignKey("Continent_Id")]
public virtual Continent Continent { get; set; }
}
Controller class ( create function )
//
// GET: /Countries/Create
public ActionResult Create()
{
ViewBag.Continent_Id = new SelectList(db.Continents, "Id", "Name");
return View();
}
//
// POST: /Countries/Create
[HttpPost]
public ActionResult Create(Country country)
{
var errors = ModelState.Values.SelectMany(v => v.Errors); //to check the errors
if (ModelState.IsValid)
{
db.Countries.Add(country);
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.Continent_Id = new SelectList(db.Continents, "Id", "Name", country.Continent_Id);
return View(country);
Just before the line if (ModelState.IsValid) put this
ModelState.Remove("v_id");
Where v_id is your primarykey column name in your case
I fixed this issue by putting the Required validation off of Continent, and set it only at the Continent_Id. Now the ID property is required, but the Continent isn't.
public class Country
{
public int Id { get; set; }
[Required, MaxLength(25)]
public string Name { get; set; }
[MaxLength(5)]
public string Abbreviation { get; set; }
[Required] //added Required
public int Continent_Id { get; set; }
//Navigation
[ForeignKey("Continent_Id")] //removed Required
public virtual Continent Continent { get; set; }
}
Thanks for the responses !
I'm not sure, but I believe your issue is timing. Model validation happens automatically during binding; at that time, the Continent property is null. You set the property later but the model state is not re-evaluated when you check IsValid. I see three options:
Quick and dirty: Take the Required validation off of Continent and validate Continent_Id instead, adding a check in the controller to ensure a valid Continent is retrieved from Find().
Most work: Create a custom model binder to actually use the Continent_Id to retrieve and populate the Continent. You are almost there on this one since having both Continent_Id and Continent as properties of Country is redundant and an opportunity for inconsistencies.
Probably best option: Make your controller accept a view model that only has the data you expect to come back from the form and populate a Country object from it.
The reason the ModelState isn't valid is because you have marked the Continent property as required but in i guess in your view you don't have form fields the will bind to some properties of the Continent object.
So either don't mark the Continent object as required or provide a hidden field with a name of Continent.Id or Continent.Name so that the model binder will populate the Continent property:
#Html.HiddenFor(m => m.Continent.Id)
But that will lead to the next problem: You habe marked the Name property of the Continent class as required so you will have to provide a form field for that property too.
The base problem is, that you try to reuse your repository classes as viewmodel classes.
A better approach would be to use separate classes as viewmodels to pass your data between the controller and the view:
class CountryViewModel {
public int Id { get; set; }
[Required, MaxLength(25)]
public string Name { get; set; }
[MaxLength(5)]
public string Abbreviation { get; set; }
public int Continent_Id { get; set; }
}
To map between your Country and CountryViewModel object use a mapper like AutoMapper.
I have a DbDataController which delivers a List of Equipment.
public IQueryable<BettrFit.Models.Equipment> GetEquipment() {
var q= DbContext.EquipmentSet.OrderBy(e => e.Name);
return q;
}
In my scaffolded view everything looks ok.
But the Equipment contains a HashSet member of EquipmentType. I want to show this type in my view and also be able to add data to the EquipmentType collection of Equipment (via a multiselect list).
But if I try to include the "EquipmentType" in my linq query it fails during serialisation.
public IQueryable<BettrFit.Models.Equipment> GetEquipment() {
var q= DbContext.EquipmentSet.Include("EquipmentType").OrderBy(e => e.Name);
return q;
}
"Object Graph for Type EquipmentType Contains Cycles and Cannot be Serialized if Reference Tracking is Disabled"
How can I switch on the "backtracking of references"?
Maybe the problem is that the EquipmentType is back-linking through a HashSet? But I do not .include("EquipmentType.Equipment") in my query. So that should be ok.
How is Upshot generating the model? I only find the EquipmentViewModel.js file but this does not contain any model members.
Here are my model classes:
public class Equipment
{
public Equipment()
{
this.Exercise = new HashSet<Exercise>();
this.EquipmentType = new HashSet<EquipmentType>();
this.UserDetails = new HashSet<UserDetails>();
}
public int ID { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public string Picture { get; set; }
public string Link { get; set; }
public string Producer { get; set; }
public string Video { get; set; }
public virtual ICollection<EquipmentType> EquipmentType { get; set; }
public virtual ICollection<UserDetails> UserDetails { get; set; }
}
public class EquipmentType
{
public EquipmentType()
{
this.Equipment = new HashSet<Equipment>();
this.UserDetails = new HashSet<UserDetails>();
}
public int ID { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public virtual ICollection<Equipment> Equipment { get; set; }
public virtual ICollection<UserDetails> UserDetails { get; set; }
}
try decorating one of the navigation properties with [IgnoreDataMember]
[IgnoreDataMember]
public virtual ICollection<Equipment> Equipment { get; set; }
The model generated by upshot can be found on the page itself. In your Index view you will see the UpshotContext HTML helper being used (given that you are using the latest SPA version), in which the dataSource and model type are specified.
When the page is then rendered in the browser, this helper code is replaced with the actual model definition. To see that, view the source code of your page in the browser and search for a <script> tag that starts with upshot.dataSources = upshot.dataSources || {};
Check here for more info about how upshot generates the client side model.
As for the "backtracking of references", I don't know :)
I figured out - partially how to solve the circular reference problem.
I just iterated over my queried collection (with Include() ) and set the backreferences to the parent to NULL. That worked for the serialisation issue which otherwise already breaks on the server.
The only problem now is the update of a data entity - its failing because the arrays of the referenced entitycollection are static...
To solve the cyclic backreference, you can use the IgnoreDataMember attribute. Or you can set the back reference to NULL before returning the data from the DbDataController
I posted a working solution to your problem in a different question, but using Entity Framework Code First.
https://stackoverflow.com/a/10010695/1226140
Here I show how to generate your client-side model manually, allowing to you to map the data however you please
I have a class, which has 8 properties / 8 columns in DB. In the Edit page, I want to exclude the AddedDate and UserID fields. When a user edits a voucher, he can't overwrite the AddedDate or UserID values in the DB.
public class Voucher
{
public int ID { get; set; }
public string Title { get; set; }
public string SiteName { get; set; }
public string DealURL { get; set; }
public DateTime AddedDate { get; set; }
public DateTime? ExpirationDate { get; set; }
public string VoucherFileURL { get; set; }
public Guid UserID { get; set; }
}
Here is what I have for Edit controller:
// POST: /Voucher/Edit/5
[HttpPost]
public ActionResult Edit([Bind(Exclude = "AddedDate")]Voucher voucher)
{
if (ModelState.IsValid)
{
db.Entry(voucher).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(voucher);
}
On Edit page, when I click on submit, I got the following error:
System.Data.SqlServerCe.SqlCeException: An overflow occurred while converting to datetime.
Seems like the AddedDate didn't get excluded from the voucher object and triggered the error.
Would you please let me know how to fix it? Thanks!
(it is an updated version of asp.net mvc3 UpdateModel exclude properties is not working, I will go with another approach)
Never use your domain entities as action arguments and never pass your domain entities to your views. I would recommend you to use view models. In the view model you will include only the properties that you want to be bound from the view. The view model is a class that's specifically tailored to the requirements of a given view.
public class VoucherViewModel
{
public int ID { get; set; }
public string Title { get; set; }
public string SiteName { get; set; }
public string DealURL { get; set; }
public DateTime? ExpirationDate { get; set; }
public string VoucherFileURL { get; set; }
}
and then:
[HttpPost]
public ActionResult Edit(VoucherViewModel model)
{
// TODO: if the view model is valid map it to a model
// and pass the model to your DAL
// To ease the mapping between your models and view models
// you could use a tool such as AutoMapper: http://automapper.org/
...
}
UPDATE:
In the comments section #Rick.Anderson-at-Microsoft.com points out that while I have answered your question I haven't explained where the problem comes from.
The thing is that DateTime is a value type meaning it will always have a value. The [Bind(Exclude = "AddedDate")] works perfectly fine and it does what it is supposed to do => it doesn't bind the AddedDate property from the request. As a consequence the property will have its default value which for a DateTime field is 1/1/0001 12:00:00 AM and when he attempts to save this in SQL Server it blows because SQL Server doesn't support such format.
I have an object like this
public class ParentEntityInfo
{
public long? ParentId { get; set; }
public string EntityName { get; set; }
public string ParentProperty { get; set; }
}
and view for this object is:
<%=Html.Hidden("parentInfo.ParentId", parentInfo.ParentId)%>
<%=Html.Hidden("parentInfo.ParentProperty", parentInfo.ParentProperty)%>
<%=Html.Hidden("parentInfo.EntityName", parentInfo.EntityName)%>
I have the case where parentInfo is null and I post this form to controller. On the controller action
public ActionResult SomeAction(..., ParentEntityInfo parentInfo)
I receive constructed object parentInfo but all properties are null. In this case I would rather prefer to have whole parentInfo to be null. I there any possibility to tell default model binder do not pass such object? Or probably I can modify something in this code to make it work this way. I think in mvc 2.0 it worked this way.
Use the HiddenFor(...) helper instead.
I think the default model binder will always use Activator.CreateInstance to bind complex action parameters. What you can do is use ModelState.IsValid to assess whether the parameter was bound successfully. I think in your case this will be false by default, but if not you could add the necessary attribute to ensure this behaviour e.g.
public class ParentEntityInfo
{
[Required(ErrorMessage = "Parent required")]
public long? ParentId { get; set; }
public string EntityName { get; set; }
public string ParentProperty { get; set; }
}
In my MVC application I have a problem with passing data from view to controller. I have fairly complex domain classes:
public class TaskBase : PersistableObject
{
public virtual TaskCategory Category { get; set; }
public virtual IList<TaskNote> Notes { get; set; }
public virtual string TaskTitle { get; set; }
public virtual string TaskBody { get; set; }
public virtual DateTime? CreationTime { get; set; }
public virtual User CreatedBy { get; set; }
public virtual int CompletionRatio { get; set; }
}
public class MainTask : TaskBase
{
public virtual IList<TaskBase> ChildTasks { get; set; }
public virtual User AssignedTo { get; set; }
public virtual IList<TaskHistory> History { get; set; }
}
public class TaskFormModel : ViewDomainBase
{
public MainTask Task { get; set; }
public LoginForm LoginInfo { get; set; }
}
And in my view I want to pass an instance of TaskFormModel to the controller.
<%= Html.ActionLink<TaskController>("Edit Task", (x) => x.Edit(new TaskFormModel() { Task = item, LoginInfo = Model.LoginInfo }))%>
And here is the controller action:
public ActionResult Edit (TaskFormModel taskInfo)
{
return View(ViewPageName.TaskDetailsForm, task.Task);
}
In this action method taskInfo comes null even if I pass non-null instance from view. I think I have a binding problem here. I think, writing custom model binder requires every property to be converted and also when new fields added then binder class should also be changed, so I don't want custom model binder to do this. Is there any other way to pass data to controller in this scenario? Or could custom model binder can be coded so that less code written and also when new properies are added binder class will not need to be changed?
Edit After Comments: What I am trying to achieve is basically to pass an instance from one view to another view, without querying repository/db in my controller's action.
First version of answer:
Your GET edit method should be like:
public ActionResult Edit (int id)
{
var model = taskRepository.GetTaskEditModel(id);
return View(ViewPageName.TaskDetailsForm, model);
}
and ActionLink:
<%= Html.ActionLink("Edit Task", "Edit", "Task", new { model.Task.id })%>
If you want to pass complex objects to controller, you should wrap them up in html form and pass to POST action.
In my opinion you are doing something wrong.
As I understand: you are trying to instantiate a new object, pass it to browser and get it back.
well you cant.
If object you want to edit exists already in your storage, then you should alter your ActionLink to reference it by id, and instantiate it inside your Edit action.
Take a look at default strongly typed index views created by tooling.