实体框架删除对象问题 [英] Entity Framework Delete Object Problem

问题描述

我正在获得该对象无法被删除，因为它在ObjectStateManager中找不到。而删除对象。

i am getting "The object cannot be deleted because it was not found in the ObjectStateManager". while Deleting object.

这里是代码;

//first i am filling listview control.
 private void Form1_Load(object sender, EventArgs e)
    {
        FirebirdEntity asa = new FirebirdEntity();

        ObjectQuery<NEW_TABLE> sorgu = asa.NEW_TABLE;

        foreach (var item in sorgu)
        {
            ListViewItem list = new ListViewItem();
            list.Text = item.AD;
            list.SubItems.Add(item.SOYAD);
            list.Tag = item;
            listView1.Items.Add(list);

        }
//than getting New_table entity from listview's tag property.
 private void button3_Click(object sender, EventArgs e)
    {

            using (FirebirdEntity arama = new FirebirdEntity())
            {

               NEW_TABLE del = (NEW_TABLE)listView1.SelectedItems[0].Tag;
               arama.DeleteObject(del);
               arama.SaveChanges();


            }}

推荐答案

您需要附加对象为 ObjectContext 。尝试：

NEW_TABLE del = (NEW_TABLE)listView1.SelectedItems[0].Tag;
arama.Attach(del);
arama.DeleteObject(del);
arama.SaveChanges();

附加对象由 ObjectContext 跟踪。执行删除和更新是必需的。您可以在MSDN上阅读有关附加对象的更多信息。

Attached objects are tracked by the ObjectContext. This is needed for performing deletes and updates. You can read more about attaching objects on MSDN.

编辑以澄清attach / detach：

Edit to clarify attach/detach:

private void Form1_Load(object sender, EventArgs e) {
    FirebirdEntity asa = new FirebirdEntity();

    ObjectQuery<NEW_TABLE> sorgu = asa.NEW_TABLE;
    foreach (var item in sorgu) {
        asa.Detach(item);
        // add to listView1
    }
}

另外，您应该使用块在中使用 ObjectContext 。

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