ASP.NET VB列表框DataBind不工作

Question

在我的用戶控件中，我有一個文本框，用於創建新的成員資格用戶。每個列表框都有一個設置爲membership.getallusers()的數據源來填充列表框。當列表框索引被改變時，它填充文本框以允許編輯。我想完成的是：讓每個用戶列表框都刷新以顯示創建的新用戶。即使我在成功創建用戶後調用databind()，它也不會更新。在表單上，​​我檢查是否listbox.items.count < 1，然後撥打電話databind()，確實能正常工作。有任何想法嗎？

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load 
    If ListBox3.Items.Count < 1 Then 
     For Each item As MembershipUser In Membership.GetAllUsers(0, Membership.GetAllUsers.Count + 1, Membership.GetAllUsers.Count) 
      ListBox3.Items.Add(item.UserName) 
     Next 
     Label1.Text = ListBox3.Items.Count 
     username = ListBox3.Items(0).ToString 
    Else 
     ListBox1.DataBind() 
     ListBox3.DataBind() 
    End If 
    user = Membership.GetUser 
    ListBox1.DataSource = Membership.GetAllUsers 
    ListBox1.DataBind() 
    ListBox2.DataSource = Roles.GetAllRoles 
    ListBox2.DataBind() 
    ' ListBox3.DataSource = Membership.GetAllUsers 
    'ListBox3.DataBind() 
End Sub 

Protected Sub ListBox3_SelectedIndexChanged(sender As Object, e As EventArgs) Handles    ListBox3.SelectedIndexChanged 
    txtUsername.Text = user.UserName 
    txtEmail.Text = user.Email 
    txtQuestion.Text = user.PasswordQuestion  
End Sub 

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
    Try'Creates a new user 
     Dim status As System.Web.Security.MembershipCreateStatus 
     Membership.CreateUser(txtUsername.Text, txtPassword.Text, txtEmail.Text, txtQuestion.Text, txtAnswer.Text, True, status) 
     Label1.Text = "User " & txtUsername.Text & " was created" 
     'ListBox3.Items.Clear() 
     ListBox1.DataBind() 
     'ListBox3.DataBind() 
    Catch ex As Exception 
     Label1.Text = "Error:" & ex.Message 
    End Try 
End Sub 

Answer 1

您需要在此之前的數據綁定，像這樣重新設置數據源：

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
    Try'Creates a new user 
     Dim status As System.Web.Security.MembershipCreateStatus 
     Membership.CreateUser(txtUsername.Text, txtPassword.Text, txtEmail.Text, txtQuestion.Text, txtAnswer.Text, True, status) 
     Label1.Text = "User " & txtUsername.Text & " was created" 
     'ListBox3.Items.Clear() 
     ListBox1.DataSource = Membership.GetAllUsers() ' Necessary because the DB has changed 
     ListBox1.DataBind() 
     'ListBox3.DataBind() 
    Catch ex As Exception 
     Label1.Text = "Error:" & ex.Message 
    End Try 
End Sub 

當你調用數據綁定，你可能會認爲這是當下的列表框會叫你給的方法它作爲一個數據源，但事實並非如此。在分配數據源的那一刻，檢索數據。當你實際調用數據綁定方法時，列表框將創建必要的內部控件