vb.net - 隐藏 LookUpEdit 中的列 (DevExpress)

Question

我正在尝试隐藏除 DisplayMember 之外的 LookUpEdit 控件(DevExpress 3rd party)的所有列(其功能应该看起来像独立的 ComboBox)

Properties.DataSource 是一个 DataTable，因此当我想要访问每一列以隐藏它时，程序会启动 Null ref 异常。

我做错了什么？

代码:

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

您可以只添加所需的一列，而不是隐藏列:

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

这里是示例:

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))