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我的控制器中有以下 ActionResults（为简单起见已截断）。当我发布时，我收到错误消息：ObjectStateManager 中已存在具有相同键的对象。我认为这是因为我在 GET ActionResult 中加载了一个实体：

var t = iEquipmentTaskRepository.GetSingle(taskID);

然后在帖子中再次加载它并尝试编辑/保存它。我需要向数据库添加一个新的维护实体并更新（现有）设备任务实体中的值。如何在 ObjectStateManager 中获得对 EquipmentTask 的引用？或者，将 EquipmentTask 实体作为属性添加到我的 MaintenanceViewModel 中会更好吗？我只想更新 EquipmentTask 实体中的一个属性/列

// GET
public ActionResult Create(int taskID = 0)
{
    if (taskID == 0)
    {
        return RedirectToAction("SelectEquipmentTask", "Maintenance");
    }
    else
    {
        var t = iEquipmentTaskRepository.GetSingle(taskID);

        var maintenanceViewModel = new MaintenanceViewModel
        {
            DueDate = t.MaintenanceDueDate
        };
        return View(maintenanceViewModel);
    }
}

// POST
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(MaintenanceViewModel maintenanceViewModel)
{
    if (maintenanceViewModel.DueDate != null)
        nextDueDate = maintenanceViewModel.DueDate.AddDays(7);

    Maintenance maintenance = new Maintenance();
    maintenance.RowId = maintenanceViewModel.RowId;

    // this appears to be my problem. I am loading the same EquipmentTask as the GET method does

    var t = iEquipmentTaskRepository.GetSingle(maintenanceViewModel.TaskId);
    EquipmentTask equipmentTask = new EquipmentTask();
    equipmentTask.TaskId = maintenanceViewModel.TaskId;
    equipmentTask.MaintenanceDueDate = nextDueDate;

    try
    {
        if (ModelState.IsValid)
        {
            iMaintenanceyRepository.Add(maintenance);
            iMaintenanceyRepository.Save();

            iEquipmentTaskRepository.Edit(equipmentTask);
            iEquipmentTaskRepository.Save();

            // redirect to the Details view
            return RedirectToAction("Details", "Maintenance", new { id = maintenance.RowId });
        }
    }
    catch (DataException)
    {
        //Log the error (add a variable name after DataException)
        ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists, see your system administrator.");
    }
    return View(maintenanceViewModel);
}
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1 回答 1

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我弄清楚发生了什么事。我不需要创建 EquipmentTask 的新实例（Duh）：

var t = iEquipmentTaskRepository.GetSingle(maintenanceViewModel.TaskId);

EquipmentTask equipmentTask = new EquipmentTask(); // <-- this line was not necessary

equipmentTask.TaskId = maintenanceViewModel.TaskId;
equipmentTask.MaintenanceDueDate = nextDueDate;

我没有添加新实例，只是更新现有实例。一旦我删除了这条线，它就起作用了：

var equipmentTask = iEquipmentTaskRepository.GetSingle(maintenanceViewModel.TaskId);
equipmentTask.TaskId = maintenanceViewModel.TaskId;
equipmentTask.MaintenanceDueDate = maintenanceViewModel.NextDueDate;
于 2013-07-27T21:07:35.417 回答