隱藏LookUpEdit中的列（DevExpress）

Question

我正在嘗試隱藏LookUpEdit控件（DevExpress第三方）的所有列，除了DisplayMember（它的功能應該像stander ComboBox一樣）

Properties.DataSource是一個DataTable，所以當我想訪問每一列以隱藏它時，程序會啟動Null ref異常。

我究竟做錯了什么？

代碼：

If TypeOf Me.Properties.DataSource Is DataTable Then
     Me.Properties.PopulateColumns()
     Dim dt As DataTable = CType(Me.Properties.DataSource, DataTable)

     For Each column As DataColumn In dt.Columns
         If Me.Properties.Columns(column.ColumnName) IsNot Nothing AndAlso column.ColumnName IsNot Me.DisplayMember Then
                Me.Properties.Columns(column.ColumnName).Visible = False
         End If
     Next

End If

Answer 1

您可以只添加一個所需的列，而不是隱藏列：

lookUpEdit1.Properties.Columns.Add(New LookUpColumnInfo(lookUpEdit1.Properties.DisplayMember))

這是一個例子：

Dim dataTable As New DataTable()

dataTable.Columns.Add("ID", Type.GetType("System.Int32"))
dataTable.Columns.Add("Name", Type.GetType("System.String"))
dataTable.Columns.Add("Description", Type.GetType("System.String"))

dataTable.Rows.Add(0, "Name0", "Description0")
dataTable.Rows.Add(1, "Name1", "Description1")
dataTable.Rows.Add(2, "Name2", "Description2")

lookUpEdit1.Properties.DataSource = dataTable
lookUpEdit1.Properties.DisplayMember = "Name"
lookUpEdit1.Properties.ValueMember = "ID"

lookUpEdit1.Properties.Columns.Add(New LookUpColumnInfo(lookUpEdit1.Properties.DisplayMember))

Answer 2

要在devexpress的lookupedit控件中隱藏特定列，請執行以下操作：

lookUpEdit1.Properties.PopulateColumns();
lookUpEdit1.Properties.Columns[**index**].Visible = false;