訂單驗證

Question

我有一個VB.Net Windows窗體上的4個下拉列表：Subpriority1，Subpriority2，Subpriority3和Subpriority4。

如果未輸入Subpriority1和Subpriority2的值，用戶將無法輸入Subpriority3。現在我需要一種方法來在VB中驗證它，而不必使用嵌套的IF語句。任何幫助傢伙？

Answer 1

這裏！此方法適用於多達10個控制工作：

所有你需要做的是：

1. 確保在您所設定的每個窗口都具有相同的名稱，除了最後一位。

2. 確保控制連續編號（不要緊，無論他們開始爲0或1）

3. 添加EnforceSequence（發件人，E）在組中的每個控制的方法框TextChanged。

4. 添加EnforceSequence（NameOfYourFirstControl，爲Nothing）到Form_Load事件，或將啓用爲False所有從第一個將分開設置的控件。

5. 添加下面的方法到你的窗體的代碼：

---

''' <summary>Ensure that a set of controls are available to the user sequentially.</summary> 
''' <param name="sender">The Sender parameter as provided by the Control's change event</param> 
''' <param name="e">The EventArgs parameter as provided by the Control's change event</param> 
''' <remarks> 
''' To make this work, All of the participating controls must have the same name, with a consecutive index appended. E.g. MyControl1, MyControl2, MyControl3. 
''' Add a call to EnforceSequence(sender, e) in the TextChanged event of each of the controls. 
''' </remarks> 
Private Sub EnforceSequence(ByVal sender As Object, ByVal e As System.EventArgs) 

    'The control that raised the event 
    Dim validatingContol As System.Windows.Forms.Control = CType(sender, System.Windows.Forms.Control) 

    'Get the name of the DropDown set 
    Dim controlName As String = validatingContol.Name.Substring(0, validatingContol.Name.Length - 1) 

    'Get the index of the control (i.e. the number at the end of the name) 
    Dim validatingControlIndex As Integer = Integer.Parse(validatingContol.Name.Substring(validatingContol.Name.Length - 1)) 

    'Check to see if there's another control with the same name in the sequence. 
    If Not Me.Controls(controlName & validatingControlIndex + 1) Is Nothing Then 
     'If this control is empty, set all the following controls to empty and disabled. 
     Me.Controls(controlName & validatingControlIndex + 1).Enabled = Not validatingContol.Text = "" 
     'Ask the next control to do the same check 
     EnforceSequence(Me.Controls(controlName & validatingControlIndex + 1), Nothing) 
    End If 

End Sub 

如果你有超過10個控件，然後只需更改子搶最後2位數字，但你必須以2位數字命名所有控件，例如ComboBox01

Answer 2

你應該做的是清除除第一個以外的所有下拉菜單。然後，在.SelectedIndexChanged事件上，加載第二個下拉列表的數據。重複下拉三下載第四個。