"Object reference not set to an instance of an object." Nesting Lists ASP.NET MVC LINQ Entity Framework

Question

As the title says, im getting that error when trying to get the value out of an user object to be displayed. Im using Entity Framework Code-First, so all the Models are generated, im trying to combine multiple tables with eachother. "Displaying all users with their project data and flextime" (Now flextime is just a decimal)

Model:

    public class ListModel
{
    public List<StaffModel> StaffModelList { get; set; } 
}

    public class StaffModel
{
    public FlexModel Flex { get; set; }
    public List<string> ProjectName { get; set; }
}

    public class FlexModel
{
    public User User { get; set; }
    public decimal FlexTime { get; set; }
}

View:

@model Aviato.ViewModel.ListModel 

<table class="table">
@foreach (var item in Model.StaffModelList)
    {
        <tr>
            <td>@item.Flex.User.UserId</td>
            <td>@item.Flex.FlexTime</td>
            <td>@item.ProjectName</td>
            <td>@item.Flex.User.SocialSecurityNumber</td>
            <td>@item.Flex.User.FirstName</td>
            <td>@item.Flex.User.LastName</td>
            <td>@item.Flex.User.Address1</td>
            <td>@item.Flex.User.ZipCode</td>
            <td>@item.Flex.User.City</td>
            <td>@item.Flex.User.PhoneNumber1</td>
            <td>@item.Flex.User.EmploymentStartDate</td>
            <td>@item.Flex.User.Password</td>

            @foreach (var project in item.ProjectName)
            {
                <td>@project</td>
            }

            @Html.ActionLink("Redigera", "Edit", new { id = item.Flex.User.UserId })
            @Html.ActionLink("Ta bort", "Delete", new { id = item.Flex.User.UserId })
        </tr>
       }
</table>

Controller:

private readonly AviatoModel _db = new AviatoModel(); //Database

public ActionResult Index()
    {
        var projects = _db.Projects.ToList();
        var users = _db.Users.ToList();
        var model = new ListModel();

        model.StaffModelList = new List<StaffModel>();

        foreach (var u in users)
        {
            var flexModel = new StaffModel();
            flexModel.Flex.User = u; //This is where the Error occurs.
            flexModel.Flex.FlexTime = GetFlex.Flex(u.UserId);
            model.StaffModelList.Add(flexModel);
        }

        return View(model);
    }

Please help.

About that exception: see http://stackoverflow.com/q/4660142/121309 A hint: what is the value of `flexModel.Flex` at that error line and why? — Hans Keﬆing, Oct 07 '14 at 12:48
pretty much your object is null that you're sending from your controller — jbutler483, Oct 07 '14 at 12:48
You're not assigning anything to `flexModel.Flex`, so `flexModel.Flex.User` doesn't exist — markpsmith, Oct 07 '14 at 12:51
flexModel Does not have a property or field which having the name Flex — Midhun Mundayadan, Oct 07 '14 at 12:53
@MidhunMundayadan - he's not assigning to a `FlexModel` type, he's assigning to a `StaffModel` type _called_ flexModel, which does have a `Flex` property - confusing, i know! — markpsmith, Oct 07 '14 at 13:00
@markpsmith Indeed, took me a moment to figure that one out! — DavidG, Oct 07 '14 at 13:01

score 2 · Accepted Answer · edited Oct 07 '14 at 13:04

2

The Flex property of StaffModel is never instantiated so when you try to access a method on it, you get the NullReferenceException. Add a constructor to your class like this to create it as an empty object:

public class StaffModel
{
    public StaffModel()
    {
        Flex = new FlexModel();
    }

    //snip
}

edited Oct 07 '14 at 13:04

Hans Keﬆing

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answered Oct 07 '14 at 12:53

DavidG

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"Object reference not set to an instance of an object." Nesting Lists ASP.NET MVC LINQ Entity Framework

1 Answers1