datagridview 中的级联组合框无法正常工作

Question

在 Windows 窗体中实现级联 ComboBox 时卡住了。我有一个DataSet 和一些DataTable。现在，我有一个 DataGridView 控件，它将有两个 ComboBox ：

• 一个ComboBox 将显示所有DataTable 名称
• 另一个将填充所选DataTable的列名

问题是级联无法正常工作。完整代码如下：

DataSet ds = new DataSet();
public Form1()
{
    InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
    ds.Tables.Add(GetTable1());
    ds.Tables.Add(GetTable2());

    IList<string> lstTables = ds.Tables.OfType<DataTable>().Select(dt => dt.TableName).ToList();
    dgvColumn1.DataSource = lstTables;
    dgvColumn1.ValueType = typeof(string);

}      

private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
    if ((dataGridView1.CurrentCell != null)
        && (dataGridView1.CurrentCell.ColumnIndex == 0))
    {
        DataGridViewComboBoxColumn cboColumn = (DataGridViewComboBoxColumn)dataGridView1.Columns[1];

        if (ds.Tables[dataGridView1.CurrentCell.FormattedValue.ToString()].Columns.Count >0)
        {
            IList<string> lstColumn = ds.Tables[dataGridView1.CurrentCell.FormattedValue.ToString()].Columns.Cast<DataColumn>().Select(x => x.ColumnName).ToList();
            cboColumn.DataSource = lstColumn;
            cboColumn.ValueType = typeof(string);
        }
        else
        {
            cboColumn.DataSource = null;
        }
    }
}


private void dataGridView1_DataError(object sender, DataGridViewDataErrorEventArgs e)
{

}

DataTable GetTable1()
{
    DataTable dt1 = new DataTable("table1");
    dt1.Columns.Add("t1Col1");
    dt1.Columns.Add("t1Col2");
    dt1.Columns.Add("t1Col3");
    dt1.Columns.Add("t1Col4");
    return dt1;
}

DataTable GetTable2()
{
    DataTable dt2 = new DataTable("table2");
    dt2.Columns.Add("t2Col1");
    dt2.Columns.Add("t2Col2");
    dt2.Columns.Add("t2Col3");
    dt2.Columns.Add("t2Col4");
    return dt2;
} 

Answer 1

我试过这个：

private void Form1_Load_1(object sender, EventArgs e)
        {
            ds.Tables.Add(GetTable1());
            ds.Tables.Add(GetTable2());

            IList<string> lstTables = ds.Tables.OfType<DataTable>().Select(dt => dt.TableName).ToList();
            dataGridView1.DataSource = lstTables;
            comboBox1.DataSource = lstTables; //Setting the tables datasource for the comboBox.
        }

然后是表格组合框事件的选择变化：

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) {

            var obj = sender as ComboBox;
            string s = obj.SelectedItem.ToString();


            var y= (from x in ds.Tables.OfType<DataTable>() where x.TableName == s select x).ToList();
            if (ds.Tables.Count > 0)
            {
                IList<string> lstCol = new List<string>();
                for (int i = 0; i < y[0].Columns.Count; i++)
                {
                      // Filling the list of columns according to the selected table
                    lstCol.Add(y[0].Columns[i].ToString());
                }

                // Setting dataSource for the column ComboBox
                comboBox2.DataSource = lstCol;
                //comboBox2.ValueType = typeof(string);
            }
            else
            {
                comboBox2.DataSource = null;
            }
        }

Designer.cs

private void InitializeComponent()
        {
            this.dataGridView1 = new System.Windows.Forms.DataGridView();
            this.comboBox1 = new System.Windows.Forms.ComboBox();
            this.comboBox2 = new System.Windows.Forms.ComboBox();
            ((System.ComponentModel.ISupportInitialize)(this.dataGridView1)).BeginInit();
            this.SuspendLayout();
            // 
            // dataGridView1
            // 
            this.dataGridView1.AllowUserToAddRows = false;
            this.dataGridView1.AllowUserToDeleteRows = false;
            this.dataGridView1.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
            this.dataGridView1.Location = new System.Drawing.Point(26, 72);
            this.dataGridView1.Name = "dataGridView1";
            this.dataGridView1.Size = new System.Drawing.Size(246, 150);
            this.dataGridView1.TabIndex = 0;
            this.dataGridView1.CellValueChanged += new System.Windows.Forms.DataGridViewCellEventHandler(this.dataGridView1_CellValueChanged_1);
            // 
            // comboBox1
            // 
            this.comboBox1.FormattingEnabled = true;
            this.comboBox1.Location = new System.Drawing.Point(28, 74);
            this.comboBox1.Name = "comboBox1";
            this.comboBox1.Size = new System.Drawing.Size(121, 21);
            this.comboBox1.TabIndex = 1;
            this.comboBox1.SelectedIndexChanged += new System.EventHandler(this.comboBox1_SelectedIndexChanged);
            // 
            // comboBox2
            // 
            this.comboBox2.FormattingEnabled = true;
            this.comboBox2.Location = new System.Drawing.Point(148, 74);
            this.comboBox2.Name = "comboBox2";
            this.comboBox2.Size = new System.Drawing.Size(121, 21);
            this.comboBox2.TabIndex = 2;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(284, 261);
            this.Controls.Add(this.comboBox2);
            this.Controls.Add(this.comboBox1);
            this.Controls.Add(this.dataGridView1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load_1);
            ((System.ComponentModel.ISupportInitialize)(this.dataGridView1)).EndInit();
            this.ResumeLayout(false);

        }