订单验证

Question

我有一个VB.Net Windows窗体上的4个下拉列表：Subpriority1，Subpriority2，Subpriority3和Subpriority4。

如果未输入Subpriority1和Subpriority2的值，用户将无法输入Subpriority3。现在我需要一种方法来在VB中验证它，而不必使用嵌套的IF语句。任何帮助家伙？

Answer 1

这里！此方法适用于多达10个控制工作：

所有你需要做的是：

1. 确保在您所设定的每个窗口都具有相同的名称，除了最后一位。

2. 确保控制连续编号（不要紧，无论他们开始为0或1）

3. 添加EnforceSequence（发件人，E）在组中的每个控制的方法框TextChanged。

4. 添加EnforceSequence（NameOfYourFirstControl，为Nothing）到Form_Load事件，或将启用为False所有从第一个将分开设置的控件。

5. 添加下面的方法到你的窗体的代码：

---

''' <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 

如果你有超过10个控件，然后只需更改子抢最后2位数字，但你必须以2位数字命名所有控件，例如ComboBox01

Answer 2

你应该做的是清除除第一个以外的所有下拉菜单。然后，在.SelectedIndexChanged事件上，加载第二个下拉列表的数据。重复下拉三下载第四个。