Question

利用EF 4, C# WinForms和北风数据库,我把一个数据网连接到命令实体,然后在运行时,我创建了一个新的Combo Boxcolum。

    Entities NW;
    private void Form1_Load(object sender, EventArgs e)
    {
        NW = new Entities();
        BindingSource1.DataSource = NW.Orders;

        DataGridViewComboBoxColumn CboCol = new DataGridViewComboBoxColumn()
        {
            HeaderText = "Customer",
            DataPropertyName = " Customer ID",
            DataSource = NW.Customers.Execute(MergeOption.AppendOnly),
            ValueMember = "CustomerID",
            DisplayMember = "CompanyName"
        };
        Datagriview1.Columns.Insert(1, CboCol);
    }

with the above code, I succeeded to change values and delete rows in the datagridview, but could not add new rows by clicking on the "+" button (Add New), Error: "datagridviewcombocell is not a valid value". Is there any idea please ?

Answer 1

Because you bind the DataGridViewComboBoxColumn with data, so when you add a new row which contains some null value is not found in your data source, and that s why it prompt you is not a valid value

我的建议不是将新记录直接添加到数据格里德·辛博-比奥中,而是把数据来源装入 com子。保持你的活力是好的。 DataGridViewCombo 仅当你从数据来源对其加以约束时,方框就总是读到。

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