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实体框架-导航属性未加载?

eager-loading lazy-loading entity-framework c#

adam78 · 技术社区 · 7 年前

我有以下实体:

public class Ticket 
{
    public int Id { get; set; }
    public string RequestBy { get; set; }
    public int PriorityId { get; set; }

    public ApplicationUser Requester { get; set; }
    public Priority Priority { get; set; }
}

public class ApplicationUser
{
    public ApplicationUser()
    {
        Id = Guid.NewGuid().ToString();
    }

    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class Priority
{
    public int Id { get; set; }
    public string Name { get; set; }
}

当我在我的控制器中创建如下新票据时:

 public class BaseController : Controller
{
    protected readonly IUnitOfWork UnitOfWork;

    public BaseController(IUnitOfWork unitOfWork)
    {
        UnitOfWork = unitOfWork; 
    }
}

public class TicketController : BaseController
{
    public TicketController(IUnitOfWork unitOfWork) : base(unitOfWork) { }

    [HttpPost]
    public ActionResult CreateTicket(CreateTicketVM viewModel)
    {
         // repopulate dropdowns incase we need to return view
         // viewModel.Priorities is IEnumerable list
         viewModel.Priorities = UnitOfWork.PriorityRepository.GetPriorities();

        //validation code removed for brevity...

        var ticket = new Ticket
        {
           RequestBy = !string.IsNullOrEmpty(viewModel.RequestBy) ? viewModel.RequestBy : User.Identity.GetUserId(),
           PriorityId = viewModel.PriorityId != 0 ? viewModel.PriorityId : (int)PriorityLevel.Medium,
        };

        UnitOfWork.TicketRepository.Add(ticket);
    }
}

现在当我调试时 var ticket 通话后 .Add(ticket) Priority 而不是 Requester 导航属性,尽管 RequestBy virtual 针对任一导航属性的关键字?

扼杀这种情况只发生在所有具有 ApplicationUser 事实上的 关键词???

使用fluent api,我定义了 请求人 FK如下:

modelBuilder.Entity<Ticket>()
 .HasRequired(x => x.Requester)
 .WithMany()
 .HasForeignKey(x => x.RequestBy);

下面是提供更多上下文的附加代码。

票据存储库:

public class TicketRepository : ITicketRepository
{
    private readonly ApplicationDbContext _context;

    public TicketRepository(ApplicationDbContext context)
    {
        _context = context;
    }

    public void Add(Ticket ticket)
    {
        _context.Ticket.Add(ticket);
    }
}

优先级存储库:

public class PriorityRepository : IPriorityRepository
{
    private readonly ApplicationDbContext _context;

    public PriorityRepository(ApplicationDbContext context)
    {
        _context = context;
    }

    public IEnumerable<Priority> GetPriorities()
    {
        return _context.Priority.ToList();
    }
}

工作单位:

public class UnitOfWork : IUnitOfWork
{
    private readonly ApplicationDbContext _context;

    public ITicketRepository TicketRepository { get; private set; }
    public IPriorityRepository PriorityRepository { get; private set; }

    public UnitOfWork(ApplicationDbContext context)
    {
        _context = context;
        TicketRepository = new TicketRepository(_context);
        PriorityRepository = new PriorityRepository(_context);
    }

    public void Complete()
    {
        _context.SaveChanges();
    }
}

1 回复 | 直到 7 年前

Ivan Stoev 7 年前

两个导航属性都不应加载。您看到的很可能是所谓导航属性修复功能的结果-如果实体已经被上下文跟踪,即使您没有特别请求,EF也会更新引用它的实体的导航属性。

您可以通过使用 var _context = new YourDbContext(); 局部变量,而不是 _context 领域或者类似这样:

var ticket = new Ticket
{
    RequestBy = !string.IsNullOrEmpty(viewModel.RequestBy) ? viewModel.RequestBy : User.Identity.GetUserId(),
    PriorityId = viewModel.PriorityId != 0 ? viewModel.PriorityId : (int)PriorityLevel.Medium,
};

bool priorityLoaded = _context.Priority.Local.Any(e => e.Id == ticket.PriorityId);
bool userLoaded = _context.ApplicationUser.Local.Any(e => e.Id == ticket.RequestBy);

_context.Ticket.Add(ticket);

根据你的描述, priorityLoaded 应该是 true 虽然 userLoaded - false .