無法投入'System.Int32'類型的對象來鍵入'System.Data.DataRowView'

Question

我需要從所選項目的數據源中檢索「id」，但它總是拋出標題中提到的相同錯誤。這裏是我的代碼

 Dim DMV As DataRowView = LbMCat.SelectedValue 'Here occurs the error 
    SelectedMainCat = DMV.Item("id") 

    'Filling the SUB Categories part/same code used to fill Main categories 
    Dim DataAdapterCats As New MySqlDataAdapter("SELECT * From catS where maincat = '" & SelectedMainCat & "';", MySqlConnection) 
    Dim dsSc As New DataSet 
    DataAdapterCats.Fill(dsSc, "SubCategories") 
    Dim SDataTable As DataTable = dsSc.Tables(0) 
    LbSCat.DataSource = SDataTable 
    LbSCat.DisplayMember = "title" 
    LbSCat.ValueMember = "id" 

Answer 1

待辦事項如下

Dim DMV As DataRowView = TryCast(LbMCat.SelectedItem, DataRowView) 

If DMV IsNot Nothing Then 
    SelectedMainCat = DMV.Item("id") 
End If 

Answer 2

嘗試直接鑄造的價值：

See it here（DirectCast（LbmCat.SelectedItem，DataRowView的）（ 「ID」）的ToString（））。它可能有幫助

Answer 3

如果你檢查的是所選的值是不是整數？

If Not TypeOf (LbMCat.SelectedValue) Is Integer Then 
    Dim DMV As DataRowView = LbMCat.SelectedValue 'Here occurs the error 
    SelectedMainCat = DMV.Item("id")  
End If