Include() in LINQ to Entities query

Question

I have the following models in my ASP.NET MVC 3 project:

public class Task {     public int Id { get; set; }     public DateTime CreatedOn { get; set; }     public TaskStatus Status { get; set; } }  public class TaskStatus {     public int Id { get; set; }     public string Description { get; set; } } 

For reference, here is my DbContext class:

public class TaskManagerSets : DbContext {     public DbSet<Task> TaskSet { get; set; }     public DbSet<TaskStatus> TaskStatusSet { get; set; } }     

Then I have a List Action in my TaskController:

TaskManagerSets dbcontext = new TaskManagerSets(); public ActionResult List() {     var tasks = from tsk in dbcontext.TaskSet.Include("TaskStatusSet")                 select tsk;     return View(tasks.ToList()); } 

Finally I have the Task List View:

 @model IEnumerable<TaskManager.Models.Task>   <ul>  @foreach (var tsk in Model)   {      <li>@tsk.Id | @tsk.CreatedOn | @tsk.Status.Description</li>   }   </ul> 

When I execute my project I get the following error:

A specified Include path is not valid. The EntityType 'CodeFirstNamespace.Task' does not declare a navigation property with the name 'TaskStatus'.

The problem is definitely on the Include("TaskStatusSet") but how should I fix this?

Answer 1

The navigation property name in your Task class is Status. So, you would have to use:

var tasks = from tsk in dbcontext.TaskSet.Include("Status")             select tsk; 

But since you are working with the DbContext API a better option is to use the type-safe overload of Include:

using System.Data.Entity; // You must add a using statement for this namespace to have the following  // lambda version of Include available  //...  var tasks = from tsk in dbcontext.TaskSet.Include(t => t.Status)             select tsk; 

You will get Intellisense and compile-time checks which helps to avoid issues with wrong strings like you had.