实体框架 4 - 删除对象

Question

我的数据库中有 3 个表

CmsMasterPages
CmsMasterPagesAdvSlots (Pure Juction Table)
CmsAdvSlots

这是我的 EDM 的图片：

我需要找出与 CmsMasterPage 连接的所有对象 CmsAdvSlot（它在我发布的代码中工作）， 并 DELETE 来自数据库的结果 (CmsAdvSlot)。

当我找到主题时，我的问题是我无法删除此对象。

Error: The object cannot be deleted because it was not found in the ObjectStateManager. 

---

        int findMasterPageId = Convert.ToInt32(uxMasterPagesListSelector.SelectedValue);
        CmsMasterPage myMasterPage = context.CmsMasterPages.FirstOrDefault(x => x.MasterPageId == findMasterPageId);
        var resultAdvSlots = myMasterPage.CmsAdvSlots;
        // It is working until here
        foreach (var toDeleteAdv in resultAdvSlots)
        {
            context.DeleteObject(myMasterPage.CmsAdvSlots.Any()); // ERORR HERE!!
            context.SaveChanges();
        }

---

知道如何解决吗？谢谢你的时间！ :-)

Answer 1

试试这个：

while (myMasterPage.CmsAdvSlots.Count > 0)
{
  var slot = myMasterPage.CmsAdvSlots.First();
  myMasterPage.CmsAdvSlots.Remove(slot); // This is required only in some scenarios - it depends on type of entities you are using.
  context.DeleteObject(slot);
}

context.SaveChanges();

Answer 2

context.DeleteObject(myMasterPage.CmsAdvSlots.Any());
myMasterPage.CmsAdvSlots.Any() 应该返回一个布尔值 您应该尝试改用myMasterPage.CmsAdvSlots.First()！

Answer 3

.Any() 返回一个布尔值。请改用.First()，.First() 在您的情况下将返回第一个CmsAdvSlot。

如果你想删除所有CmsAdvSlot，我会按照@Ladislav Mrnka 的例子。