Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim dt As New DataTable
dt = CType(Session("buyitems"), DataTable)
If (dt Is Nothing) Then
Label5.Text = dt.Rows.Count.ToString()
Else
Label5.Text = "0"
End If
End Sub
Protected Sub DataList1_ItemCommand(source As Object, e As DataListCommandEventArgs) Handles DataList1.ItemCommand
Dim dlist As DropDownList = CType(e.Item.FindControl("DropDownList1"), DropDownList)
Response.Redirect("AddToCart.aspx?id=" e.CommandArgument.ToString() "&quantity=" dlist.SelectedItem.ToString)
End Sub
我得到的例外System.NullreferenceException是“物件參考未設定為物件的實體。
例外詳情
uj5u.com熱心網友回復：
如果您DataTabl在Session變數中存盤了一個e，buyitems那么New在宣告區域變數時不要創建一個。
我認為你只是在If陳述句中顛倒了賦值。
似乎沒有一個DataTable在Session變數。
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim dt As DataTable
dt = CType(Session("buyitems"), DataTable)
If dt Is Nothing Then
Label5.Text = "0"
Else
Label5.Text = dt.Rows.Count.ToString()
End If
End Sub
轉載請註明出處，本文鏈接：https://www.uj5u.com/shujuku/393719.html