I'm developing a small app in order to better understand how MVC3 anda Razor works. I'm using MVC3, all code was generated automatically (dbContext via T4, Controller via Add Controller, Databese from EDMX model...).
In my model I have this simple model:
http://i.stack.imgur.com/nyqu4.png
public partial class Application
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ApplicationType ApplicationType { get; set; }
}
public partial class ApplicationType
{
public int Id { get; set; }
public string Type { get; set; }
}
As you can see, ApplicationType is basically an enum (shame that EF 4 has no support for enums). So, in my ApplicationController I have this:
public ActionResult Create()
{
ViewBag.AppTypes = new SelectList(db.ApplicationTypes.OrderBy(c => c.Type), "Id", "Type");
return View();
}
[HttpPost]
public ActionResult Create(Application application)
{
if (ModelState.IsValid)
{
db.Applications.Add(application);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(application);
}
And in my view:
#Html.DropDownListFor(model => model.ApplicationType.Id, (SelectList)ViewBag.AppTypes, "Choose...")
Now I'm facing two problems:
1) ApplicationType not being populated:
As #Html.DropDownListFor renders only a simple select, it fills the ID, but does not fill Type property as you can see below (sorry, I can't post images as I'm new here):
http://i.stack.imgur.com/96IR1.png
In the picture you can see that the ID is ok, but Type is empty.
What I'm doing wrong?
2) Duplicated Data
The second problem is that if I fill the Type property manually during debug (simulating a correct workflow scenario), ApplicationType is being duplicated in the database, instead of only referring to an old registry.
So, how can I make #Html.DropDownListFor refer to a previous existing item instead of creating a new one?
Thanks for your help!
I believe the mistake you're making is using your domain models in the view and assuming that on post the entire model should be completely binded and ready to store in the database. While it is possible to use domain models in the view, it's better practice to create separate View Models.
For example :
public class ApplicationViewModel
{
public int Id { get; set; }
public string Name { get; set; }
public SelectList ApplicationTypeList { get; set; }
public string ApplicationTypeId { get; set; }
}
In your view:
#Html.DropDownListFor(model => model.ApplicationTypeId, Model.ApplicationTypeList , "Choose...")
In your controller
[HttpPost]
public ActionResult Create(ApplicationViewModel model)
{
if (ModelState.IsValid)
{
Application application = new Application()
{
Id = model.Id,
Name = model.Name,
ApplicationType = db.ApplicationTypes
.First(a => a.Id == model.ApplicationTypeId);
};
db.Applications.Add(application);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(model);
}
You can then make verifying that your View Model's ApplicationTypeId corresponds to a real application type part of your modelstate's verification. You can use AutoMapper to speed up the process of converting view models to domain models.
Have you tried:
#Html.DropDownListFor(model => model.ApplicationType.Id, m => m.ApplicationType.Type, "Choose...")
Note the second parameter change.
Related
I'm building an MVC 3 website. I have a model looking like this:
public class Survey
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public DateTime DateStart { get; set; }
public DateTime DateEnd { get; set; }
// Not in view
public DateTime DateCreated { get; set; }
// Not in view
public DateTime DateModified { get; set; }
}
Based on this I also have a View Model to edit the survey information:
public class SurveyEditViewModel
{
public Guid Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public DateTime DateStart { get; set; }
public DateTime DateEnd { get; set; }
}
When the user finishes editing I would like to persist the changes. Here's my controller post action:
[HttpPost]
public ActionResult Edit(SurveyEditViewModel model)
{
// Map the view model to a domain model using AutoMapper
Survey survey = Mapper.Map<SurveyEditViewModel, Survey>(model);
// Update the changes
_repository.Update(survey);
// Return to the overview page
return RedirectToAction("Index");
}
In my repository (it's a generic one for now) I have the following code:
public void Update(E entity)
{
using (ABCDataContext context = new ABCDataContext())
{
context.Entry(entity).State = System.Data.EntityState.Modified;
context.SaveChanges();
}
}
When this executes I get the following error: "Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries."
I guess this was to be expected. Mapping from the view model to the model doesn't give me a complete Survey object.
I could modify my controller to look like this. And then it works:
[HttpPost]
public ActionResult Edit(SurveyEditViewModel model)
{
// Map the model to a real survey
survey = _repository.Find(model.Id);
survey.Name = model.Name;
survey.Description = model.Description;
survey.DateStart = model.DateStart;
survey.DateEnd = model.DateEnd;
// Update the changes
_repository.Update(survey);
// Return to the overview page
return RedirectToAction("Index");
}
But I was wondering if a better way is available?
[HttpPost]
public ActionResult Edit(SurveyEditViewModel model)
{
// Fetch the domain model to update
var survey = _repository.Find(model.Id);
// Map only the properties that are present in the view model
// and keep the other domain properties intact
Mapper.Map<SurveyEditViewModel, Survey>(model, survey);
// Update the changes
_repository.Update(survey);
// Return to the overview page
return RedirectToAction("Index");
}
I am developing an ASP.Net MVC 3 Web application and I recently posted a question about how to display a checkboxlist
ASP.Net MVC 3 Retrieve Checkbox List Values
and thanks to the help from RubbleFord and Darin Dimitrov I was able to get this working.
This works nicely for one checkboxlist, however, I now need to be able to display several checkboxlists on the same View, ie, see image attached.
The ViewModels I use to currently display one list are as follows;
public class ViewModelShiftSubSpecialties
{
public ListItem specialtyName { get; set; }
public IEnumerable<ViewModelCheckBox> SubSpecialityList { get; set; }
}
public class ViewModelCheckBox
{
public string Id { get; set; }
public string Name { get; set; }
public bool Checked { get; set; }
}
And within my Controller I populate ViewModelShiftSubSpecialties like so:
var subSpecialties = GetSubSpecialtiesForSpecialty(5);
ViewModelShiftSubSpecialties viewModel = new ViewModelShiftSubSpecialties();
var checkBoxList = new List<ViewModelCheckBox>();
viewModel.specialtyName = _listService.GetListItemByID(5); //Medicine Specialty
foreach (var item in subSpecialties)
{
ViewModelCheckBox chkBox = new ViewModelCheckBox { Id = item.subID.ToString(), Name = item.ListSub.description, Checked = false };
checkBoxList.Add(chkBox);
}
viewModel.SubSpecialityList = checkBoxList;
In my View, I display the list name and also use an Editor template to display the checkboxlist
<h3>#Model.specialtyName.description</h3>
#Html.EditorFor(m => m.SubSpecialityList)
However, I am totally stumped as how to get the above code to work with multiple checkboxlists on one View. Is this even possible?
I would really appreciate if someone could please help me with this.
Thanks.
It looks like you've done all the work already. You already have an Editor Template that works correctly with a ViewModelCheckBox IEnumerable. Editor templates wouldn't be useful if you couldn't reuse them for the same datatype. You just need to use it three times. Just extend your ViewModel
public class ViewModelShiftSubSpecialties
{
public ListItem specialtyName { get; set; } //Might need 3 of these
public IEnumerable<ViewModelCheckBox> SubSpecialityList1 { get; set; }
public IEnumerable<ViewModelCheckBox> SubSpecialityList2 { get; set; }
public IEnumerable<ViewModelCheckBox> SubSpecialityList3 { get; set; }
}
Create all three in your controller (and give them better names then I did).
And then in your View
#Html.EditorFor(m => m.SubSpecialityList1)
#Html.EditorFor(m => m.SubSpecialityList2)
#Html.EditorFor(m => m.SubSpecialityList3)
Alternatively you could create a class that contains a single specialty name and IEnumerable ViewModelCheckBox, and have your ViewModel have an IEnumerable of this new class. Then create a new Editor Template for this new class. I think this is worth it if your list size is variable/ might change. Otherwise I'd use the earlier solution for a simple fix.
public class ViewModelShiftSubSpecialties
{
public class IEnumerable<SubSpecialty> { get; set; }
}
public class SubSpecialty
{
public ListItem specialtyName { get; set; }
public IEnumerable<ViewModelCheckBox> SubSpecialityList
}
I have a class Article:
public class Article
{
public int Id { get; set; }
public string Text { get; set; }
public Title Title { get; set; }
}
And Title:
public class Title
{
public int Id { get; set; }
public string Name { get; set; }
public int MaxChar { get; set; }
}
Before you can write an Article, you have to choose your Title from a list, so your StringLength for Article.Text can be determined. Meaning, this article can only have a certain amount of chars, deppending on what 'Title' the writer has. Example: Title.Name "Title1" can only write an article with 1000 chars (MaxChar), and Title.Name "Title2" can write an article with 3000 chars. So. Thats means the the string length for Article.Text has to come from Title.MaxChar.
The Title entity is prefixed data that will be stored in the db.
Here's what ive done sone far:
The titles from the db are listed in a view, with a link to create action of the ArticleController with a "title" querystring:
#Models.Title
#foreach (var item in Model) {
#Html.ActionLink(item.Name, "Create", "Article", new { title = item.Id}, new FormMethod())
}
You fill the form, and post it. The HttpPost Create action:
[HttpPost]
public ActionResult Create(Article article)
{
if (article.Text.Length > article.Title.MaxChar)
{
ModelState.AddModelError("Text",
string.Format("The text must be less than {0} chars bla bla", article.Title.MaxChar));
}
if (ModelState.IsValid)
{
db.Article.Add(article);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(hb);
}
Here's the issue. The controller also adds a new Title entity. So the next time I navigate to the view where I have to choose Title, there's a duplicate of the last entity I used to write an article.
Should I do this in an entirly new way, or is there a small tweak. Only other thing I can think of, is just sending the MaxChar as a querystring, and have no relations between the models at all. Just seems a bit silly/webforms kindda.
Cheers
UPDATE #1:
Maybe im doing this the wrong way?
Get Create action
public ActionResult Create(int title)
{
var model = new Article
{
Title = db.Title.Find(title)
};
return View(model);
}
Or maybe its in the Model? Like, do I have to set foreign keys? Something like:
[ForeignKey("Title")]
public int MaxChar { get; set; }
public virtual Title Title { get; set; }
But im pretty sure I read some where that it isnt necesary, that EF takes care of that.
Easiest way would probably be to attach the title to the context in your Create action:
// ...
if (ModelState.IsValid)
{
db.Titles.Attach(article.Title);
db.Article.Add(article);
db.SaveChanges();
return RedirectToAction("Index");
}
// ...
Attach tells EF that article.Title already exists in the database, thereby avoiding that a new Title is inserted when you add the article to the context.
You need to have a distinction between your MVC model and your Entities model. Your MVC Article model should look something like this (bear in mind there are some religious debates about what goes into a model):
public class Article
{
public int Id { get; set; }
public string Text { get; set; }
public int TitleID { get; set; }
public IEnumerable<Title> AvailableTitles {get;set;}
}
In your view, you can create a dropdown based off the available titles, and bind it to the TitleID property. The list of available titles would be populated in the parameterless controller method (and the model-bound method as well).
When your model-bound method brings back the TitleID, instantiate the Title object from the Entities framework based off the ID. Create your Entities Article object using that Title object, and save your changes. This should get you where you want to be.
I have a multi select list in my View to send to controller a list of Users. My View receives the users, but is not sending back to controller. What am I missing?
My controller is:
// GET:
public ActionResult Create(User user)
{
ViewModel model = new ViewModel();
Interaction interact = new Interaction();
model.Users= Repository.GetUsers();
model.Interacao = interact;
return View( model );
}
In my view, the listBox is:
#Html.ListBoxFor( model => model.Users, new MultiSelectList( Model.Users, "Id", "Name" ) )
Can Anyone tell me where I am wrong?
You shouldn't be binding with model.Users as first argument as this represents a list. The first argument need to be an array of string/integer which will contain the selected values:
Example:
public class MyViewModel
{
pubilc string[] SelectedUserIds { get; set; }
public IEnumerable<UserViewModel> Users { get; set; }
}
public class UserViewModel
{
public string Id { get; set; }
public string Name { get; set; }
}
and then:
#Html.ListBoxFor(
model => model.SelectedUserIds,
new MultiSelectList(Model.Users, "Id", "Name")
)
which will successfully bind to:
[HttpPost]
public ActionResult Index(string[] selectedUserIds) { ... }
or:
[HttpPost]
public ActionResult Index(MyViewModel model) { ... }
but of course in the second case you will only get the SelectedUserIds property populated as that's the only thing sent from the view. If you need to redisplay the same view (due to model errors for example) you will need to repopulate the Users collection property of the vie model as it won't be persisted.
I have created MVC3 application using Entity Framework Code First method. My model is very simple:
public class Employee
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public int YearsAtCompany { get; set; }
}
and context class is
public class EmployeeDB : DbContext
{
public DbSet<Employee> Employees { get; set; }
}
and controller looks like this:
EmployeeDB context = new EmployeeDB();
public ActionResult Index()
{
return View(context.Employees);
}
}
I have created EmployeesDb.mdf and Employee table.
but I get this error:
The model item passed into the dictionary is of type 'System.Data.Entity.DbSet`1[DFEmployees.Models.Employee]', but this dictionary requires a model item of type 'DFEmployees.Models.Employee'.
[Updated]
#model DFEmployees.Models.Employee
#{
ViewBag.Title = "Index";
}
<h2>Index</h2>
Please suggest solution.
It's looks like your view are waiting for a single employee, and you are triying to fill the view with a DBSet of employees.
To solve it, you can set the #model of the view to an IEnumerable of employees, or send only one employee to the view, depending of what are you showing in the view.
EDIT: I think this problem is not related with the previous one. Check this link, I hope it helps you: LINK
Your controller action returns a list of employees so adapt your model respectively in the view:
#model IEnumerable<DFEmployees.Models.Employee>
Or if you wanted to use a single employee make sure you pass a single employee to the view:
public ActionResult Index()
{
return View(context.Employees.FirstOrDefault());
}
and then you can have:
#model DFEmployees.Models.Employee