Help with displaying master detail data into mvc3 view - asp.net-mvc

Question

I have the following models:
public class Page
{
public int PageID { get; set; }
public string Name { get; set; }
public string Content { get; set; }
public DateTime? DateCreated { get; set; }
public bool IsPublished { get; set; }
public string ModifiedBy { get; set; }
public DateTime? DateModified { get; set; }
public int UserID { get; set; }
public int CategoryID { get; set; }
public virtual User User { get; set; }
public virtual Category Category { get; set; }
}
public class Category
{
public int CategoryID { get; set; }
[Required(ErrorMessage = "Category name is required.")]
[Display(Name = "Category Name")]
public string Name { get; set; }
public virtual ICollection<Page> Pages { get; set; }
}
and I want to populate this navigation list:
<div id="centeredmenu" class="nav-border nav-color">
<ul>
#foreach (var pages in Model)
{
<li>CATEGORY NAME GOES HERE
<ul>
#foreach (var pages in Model)
{
<li>PAGE NAMES GO HERE</li>
}
</ul>
</li>
}
</ul>
</div>
but I'm having problems implementing the controller. I tried this ViewModel:
public class MainPageModels
{
public Category Categories { get; set; }
public Page Pages { get; set; }
}
but it just confused me even more with this error message:
System.Data.Edm.EdmEntityType: : EntityType 'MainPageModels' has no key defined. Define the key for this EntityType.
System.Data.Edm.EdmEntitySet: EntityType: EntitySet �MainModels� is based on type �MainPageModels� that has no keys defined.
This is my controller:
public ActionResult Index()
{
var pages = db.MainModels.Select(p => p.Pages).Select(c => c.Category);
return View(pages);
}
I may be missing something simple here.

Answer 1

Posting this here for the code/syntax
public class Person
{
[Key]
public int PersonID { get; set; }
public string Name { get; set; }
public string LastName { get; set; }
}
public class DataContext : DbContext
{
EntitySet<Person> Persons { get; set; }
}
Your View Model can then do the following
public class PersonAddViewModel
{
public string Name { get; set; }
public string LastName { get; set; }
public void CreateViewModelFromDataModel(Person person)
{
this.Name = person.Name;
this.LastName = person.LastName ;
}
}
This is just an example, just to show the difference between a Data Model and a View Model
Your View would then be a strongly typed view of PersonAddViewModel

Answer 2

Here my solution to my parent-child list problem:
I created a ViewModel to house both my categories and pages:
public class HomeViewModels
{
[Key]
public int HomeViewKey { get; set; } //This is a MUST!
public IEnumerable<Category> ViewCategories { get; set; }
public IEnumerable<Page> ViewPages { get; set; }
public void CreateHomeViewModel(IEnumerable<Category> categories,
IEnumerable<Page> pages)
{
this.ViewCategories = categories;
this.ViewPages = pages;
}
}
Then edited my controller to populate the viewmodel:
public ActionResult Index()
{
HomeViewModels homePages = new HomeViewModels();
homePages.CreateHomeViewModel(db.Categories.ToList(),
db.Pages.ToList());
return View(homePages);
}
and finally creating the ul-li lists with the following:
#{var hvCategories = Model.ViewCategories;}
#foreach (var categories in hvCategories)
{
<li>#Html.ActionLink(categories.Name, "Index", "Home")
<ul>
#{var hvPages = Model.ViewPages
.Where(p => p.CategoryID == categories.CategoryID);}
#foreach (var pages in hvPages)
{
<li>#Html.ActionLink(pages.Name, "Index", "Home")</li>
}
</ul>
</li>
I hope this helps anyone who plans to build a nested list using a parent-child model. This took me two days to figure out. Cheers!