Question

我的桌子有这种关系。 Activity，Workstation，Platform，Part是查找表。

我ActivitWorkstation包含(ActivityId, WorkstationId)和Activity个表的Workstation个外键。

我还PlatformPart包含(PlatformId, PartId)和Platform表的Part个外键。

最后，我有PartStaging表，(ActivityWorkstationId, PlatformPartId)和ActivityWorkstation表有PlatformPart个外键。

以下是我的PartStaging修改方法：

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(PartStagingVM partstagingvm)
{
    if (ModelState.IsValid)
    {
        PartStaging partstaging = new PartStaging();

        var activityWorkstation = db.ActivityWorkstations.FirstOrDefault(aw => aw.ActivityId == partstagingvm.ActivityId && aw.WorkstationId == partstagingvm.WorkstationId);

        if (activityWorkstation == null)
        {
            activityWorkstation = new ActivityWorkstation
            {
                ActivityId = partstagingvm.ActivityId,
                WorkstationId = partstagingvm.WorkstationId
            };

            db.Entry(activityWorkstation).State = EntityState.Added;
        }

        var platformPart = db.PlatformParts.FirstOrDefault(pp => pp.PlatformId == partstagingvm.PlatformId && pp.PartId == partstagingvm.PartId);

        if (platformPart == null)
        {
            platformPart = new PlatformPart
            {
                PlatformId = partstagingvm.PlatformId,
                PartId = partstagingvm.PartId
            };

            db.Entry(platformPart).State = EntityState.Added;
        }

        var partStaging = db.PartStagings.FirstOrDefault(ps => ps.ActivityWorkstationId == activityWorkstation.Id && ps.PlatformPartId == platformPart.Id);

        if (partStaging != null && partStaging.Id != partstagingvm.Id)
        {
            TempData["Message"] = "The record already exists.";
        }
        else
        {
            partstaging.Id = partstagingvm.Id;
            partstaging.ActivityWorkstationId = activityWorkstation.Id;
            partstaging.PlatformPartId = platformPart.Id;
            partstaging.Description = partstagingvm.Description;

            db.Entry(partstaging).State = EntityState.Modified;
            db.SaveChanges();

            TempData["Message"] = "The record has been modified.";
        }

        return RedirectToAction("Edit");
    }

    return View(partstagingvm);
}

我可以修改ActivityWorkstation。我可以修改PlatformPart。当记录已经存在时，它阻止我更新。但是在编辑Description时我遇到了问题。它应该是最简单的更新，因为我所要做的就是分配：

partstaging.Description = partstagingvm.Description

但是当我提交时，我收到了这个错误：

An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidOperationException: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.

Source Error: 


Line 216:                    partstaging.Description = partstagingvm.Description;
Line 217:
Line 218:                    db.Entry(partstaging).State = EntityState.Modified;
Line 219:                    db.SaveChanges();
Line 220:

我错过了什么？

在ObjectStateManager中，MVC 4 EF更新失败的对象已经存在

0 个答案: