[英]Selecting a value in combobox that's populated from a DataTable
我有一個由 DataTable 填充的組合框,如下所示。 我希望能夠設置顯示哪個項目。 要設置的值是將在“Id”列中找到的字符串。
public DataTable list = new DataTable();
public ComboBox cbRates = new ComboBox();
//prepare rates combo data source
this.list.Columns.Add(new DataColumn("Display", typeof(string)));
this.list.Columns.Add(new DataColumn("Id", typeof(string)));
//populate the rates combo
int counter = 0;
foreach (string item in dropdownItems)
{
this.list.Rows.Add(list.NewRow());
if (counter == 0)
{
this.list.Rows[counter][0] = "Select Rate..";
this.list.Rows[counter][1] = "";
}
else
{
string[] itemSplit = item.Split('`');
if (itemSplit.Length == 2)
{
this.list.Rows[counter]["Display"] = itemSplit[0];
this.list.Rows[counter]["Id"] = itemSplit[1];
}
else
{
this.list.Rows[counter]["Display"] = item;
this.list.Rows[counter]["Id"] = item;
}
}
counter++;
}
this.cbRates.DataSource = list;
this.cbRates.DisplayMember = "Display";
this.cbRates.ValueMember = "Id";
//now.. how to set the selected value?
int rowCount = 0;
foreach (DataRow cbrow in this.list.Rows)
{
if (DB.GetString(cbrow["Id"]) == answerSplit[1])
{
//attempting to set the SelectedIndex throws an exception
//on another combobox populated NOT from a DataTable - this does work fine.
this.cbRates.SelectedIndex = rowCount;
}
rowCount++;
}
//this doesn't seem to do anything.
foreach (DataRow dr in this.list.Rows)
{
if ((string)dr["Id"] == answerSplit[1]) this.cbRates.SelectedItem = dr;
}
//nor this
foreach(DataRow dr in this.cbRates.Items)
{
try
{
if ((string)dr["Id"] == answerSplit[1]) this.cbRates.SelectedItem = dr;
}
catch
{
MessageBox.Show("Ooops");
}
}
如果沒有 FindExactString、FindString、FindByValue 在緊湊框架中不存在,我就沒有什么可以嘗試的了。
如果嘗試使用
this.cbRates.SelectedIndex = 2;
我收到以下錯誤;
System.Exception: Exception
at Microsoft.AGL.Common.MISC.HandleAr(PAL_ERROR ar)
at System.Windows.Forms.ComboBox.set_SelectedIndex(Int32 value)
但是,如果我出於測試目的將相關代碼放入它自己的表單中,我可以毫無錯誤地設置 selectedIndex 。
我認為這些問題是相互關聯的。
您是否知道可以直接使用數據表作為數據源?
cbo.DataSource = table;
cbo.DisplayMember = "Display";
cbo.ValueMember = "Id";
您是否嘗試設置 SelectedValue? 您有一個 Id,並聲明 ValueMember 是 Id,然后使用它。
您可以這樣做,它可以工作,但如果您有大量物品,則不會太快:
foreach (object item in comboBox1.Items)
{
DataRowView row = item as DataRowView;
if ((String)row["YourDisplayMemberColumn"] == "ValueYouWantToSelect")
{
comboBox1.SelectedItem = item;
}
}
您可以通過查找與指定字符串完全匹配的項目來設置SelectedIndex
ComboBox.FindStringExact 方法
cbRates.SelectedIndex = cbRates.FindStringExact("Value_need_to_Select") ;
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