在Entity Framework中加載子實體

Question

我有這些POCO課程：

public class  Task
    {
        public int TaskId { get; set; }
        public int ProjectId { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        public DateTime StartDate { get; set; }
        public DateTime? DueDate { get; set; }
        public int UserId { get; set; }
        public string Tags { get; set; }
        public string FileName { get; set; }
        public virtual Project Project { get; set; }
        public virtual List<TaskAssigned> TaskAssigns { get; set; }
        public virtual List<TaskComment> TaskComments { get; set; }
        public virtual User User { get; set; }
    }

 public class User
    {
        public int UserId { get; set; }
        public string Name { get; set; }
        public int AccountId { get; set; }
        public string Email { get; set; }
        public string Password { get; set; }
        public bool IsAdmin { get; set; }
        public virtual Account Account { get; set; }
    }

public class TaskComment
    {
        public int TaskCommentId { get; set; }
        public int TaskId { get; set; }
        public int UserId { get; set; }
        public string Comment { get; set; }
        public string FileName { get; set; }
        public virtual User User { get; set; }
    }

    public class TaskAssigned
    {
        public int TaskAssignedId { get; set; }
        public int TaskId { get; set; }
        public int UserId { get; set; }
        public virtual User User { get; set; }
    }

我試圖通過Id獲取任務並加載此任務的所有相關實體，但TaskComment和TaskAssigned的User實體對於除Task中的User實體之外的其他用戶為null：

public Task GetTaskById(int taskId)
    {
        return context.Tasks.Include("TaskAssigns").Include("TaskComments").Include("User").Where(t => t.TaskId == taskId).FirstOrDefault();
    }

Answer 1

Include的“路徑” Include全包，這意味着您可以指定用a分隔的多個屬性. （點）和EF將包括“屬性路徑”的所有部分。

在你的情況下，這應該工作：

public Task GetTaskById(int taskId)
{
    return context.Tasks
               .Include("TaskAssigns.User")
               .Include("TaskComments.User")
               .Include("User").Where(t => t.TaskId == taskId).FirstOrDefault();
}

Answer 2

更改上下文屬性如下

context.DataContext.ContextOptions.ProxyCreationEnabled = true; 
context.DataContext.ContextOptions.LazyLoadingEnabled = true;