MVC5 MVCGRID Linq multiples tables - linq

Question

Im working with ASPNET MVC5 and i just Followed this tutorial : http://www.c-sharpcorner.com/UploadFile/4d9083/creating-simple-grid-in-mvc-using-grid-mvc/ and it works fine.
I now want to update my HomeController with 2 tables (Users & Roles),
Note : My Datacontext contains 2 tables (Users & Roles)
HomeController.cs
public ActionResult Details()
{
DataClassesUserDataContext db = new DataClassesUserDataContext();
var SchemeList = from d in db.AspNetUsers
join i in db.AspNetUserRoles
on d.Id equals i.UserId
select new { AspNetUsers = d, AspNetUserRole = i };
return View(SchemeList);
}
I return good my results
Now in my View :
My Details.cshtml
Is the probleme here ? can i call shanuMVCUserRoles.DB.AspNetUser & AspNetUserRoles ???
#model IEnumerable <shanuMVCUserRoles.DB.AspNetUser>
// possible to add other models here ? #model IEnumerable <shanuMVCUserRoles.DB.AspNetUserRole >
> <div
> class="code-cut">
> #Html.Grid(Model).Columns(columns => {
> columns.Add(c => c.UserName).Titled("UserName").Filterable(true);
> columns.Add(c => c.Id).Titled("ID").Filterable(true);
> columns.Add(c => c.PasswordHash).Titled("PasswordHash").Filterable(true);
> columns.Add(c => c.Email).Titled("Email").Filterable(true);
> columns.Add(c => c.AccessFailedCount).Titled("AccessFailedCount").Filterable(true);
> columns.Add(c => c.PhoneNumber).Titled("PhoneNumber").Filterable(true);
> columns.Add()
> .Encoded(false)
> .Sanitized(false)
> .SetWidth(30)
> .RenderValueAs(o => Html.ActionLink("Edit", "Edit", new { id = o.Id })); }).WithPaging(10).Sortable(true) </div>
i have the following error :
The model item passed into the dictionary is of type 'System.Data.Linq.DataQuery1[<>f__AnonymousType42[shanuMVCUserRoles.DB.AspNetUser,shanuMVCUserRoles.DB.AspNetUserRole]]', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[shanuMVCUserRoles.DB.AspNetUser]'.

Answer 1

you could workaround the problem by putting your AspNetUserRoles collection into ViewBag. This link shows this solution among others:
http://www.codeproject.com/Articles/687061/Multiple-Models-in-a-View-in-ASP-NET-MVC-MVC
Personally, I consider the Model as a kind of contract between my Controller and my View, so I do not like putting business information outside the Model. For example, it would be ok to store a string to format DateTimes into the ViewBag. But if I want a Controller and a View to manage Users and Roles, I want it to be clear for me and for anybody else reading the code, which can happen today, tomorrow or in ten years.
So in this case I would create a Model class:
namespace WebApplication1.Models
{
public class UsersAndRolesModel
{
public IList<shanuMVCUserRoles.DB.AspNetUser> Users { get; set; }
public IList<shanuMVCUserRoles.DB.AspNetRole> Roles { get; set; }
}
}
I would create it and populate it in my Controller.
Then in my View I would declare:
#model WebApplication1.Models.UsersAndRolesModel
and finally my grids:
#Html.Grid(Model.Users).Columns(columns => { // and so on...
#Html.Grid(Model.Roles).Columns(columns => { // and so on...
I hope this helps.
Editing:
Hi David, it depends on what you actually want to do: do you want a View showing two tables, one for all the users and one for all the roles?
In this case, a first implementation could (but should not) be:
public ActionResult Details()
{
UsersAndRolesModel model = new UsersAndRolesModel();
DataClassesUserDataContext db = new DataClassesUserDataContext();
model.Users = db.AspNetUsers.ToList();
model.Roles = db.AspNetUserRoles.ToList();
return View(model);
}
I wrote should not be because DataClassesUserDataContext must be disposed after usage. So what you really should do is:
public class HomeController : Controller
{
private DataClassesUserDataContext db = new DataClassesUserDataContext();
public ActionResult Details()
{
UsersAndRolesModel model = new UsersAndRolesModel();
model.Users = db.AspNetUsers.ToList();
model.Roles = db.AspNetUserRoles.ToList();
return View(model);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
db.Dispose();
}
base.Dispose(disposing);
}
}

Answer 2

I have edited my previous answer with some information about how the Controller could be implemented.
The NullReferenceException happens because returning
return View();
provides a null model to the View, so Model.Users and Model.Roles cause the NullReferenceException in your View.
Please note that I am returning
return View(model);
in my HomeController.
Just let me add that I avoid using DbContexts in my controllers.
I prefer implementing the Repository pattern.
You can find a nice example here:
http://www.asp.net/mvc/overview/older-versions/getting-started-with-ef-5-using-mvc-4/implementing-the-repository-and-unit-of-work-patterns-in-an-asp-net-mvc-application
It is a better approach because it allows you to create a Test project and to test your controllers by providing mock repository implementations.