组合框加载错误 [英] Combo box loading error

问题描述

我有一个场景：我在我的Form Load中加载了我的combox框和数据表，如下所示：

 m_dtDelayedDeliveryDays = GetDelayedDeliveryDays（）
 
 
 
 用于 每个 dr 作为 DataRow 在 m_dtDelayedDeliveryDays中。行
  Me  .cmbDelayedDeliveryDays.Items.Add（dr（  DeliveryDelayDays））
 下一步 
 
 cmbDelayedDeliveryDays.DataSource = m_dtDelayedDeliveryDays 
 cmbDelayedDeliveryDays。 DisplayMember =   DeliveryDelayDays 
 cmbDelayedDeliveryDays.ValueMember =   DeliveryDelayDaysID 

我也可以根据用户选择选择ID，如下所示：

 私有  Sub  cmbDelayedDeliveryDays_SelectedIndexChanged（sender 作为系统。对象，e  As  System.EventArgs）句柄 cmbDelayedDeliveryDays.SelectedIndexChanged 
 
 cmbDelayedDeliveryDays.Refresh（）
  Dim  selectedDataRow  As  DataRow =  DirectCast （cmbDelayedDeliveryDays.SelectedItem，DataRowView）。
  Dim  delayId  As   Integer  = Convert.ToInt32（selectedDataRow（  DeliveryDe layDaysID））
 
 
 结束  Sub  

我的组合框加载的值为0,3,7,15,20,30 ..

使用上面的代码我的组合box的默认值为0.我希望我的组合框默认为空。



请帮忙。



谢谢。

解决方案

 cmbDelayedDeliveryDays.ValueMember =DeliveryDelayDaysID

之后放入以下

 cmbDelayedDeliveryDays..SelectedIndex = -1 

在 Sub cmbDelayedDeliveryDays_SelectedIndexChanged 中你需要包装任何引用<的代码code> cmbDelayedDeliveryDays.SelectedItem 检查

 .SelectedIndex 

例如

 如果 cmbDelayedDeliveryDays.SelectedIndex>  0  然后 
调试。打印（cmbDelayedDeliveryDays.SelectedValue.ToString（））
 结束 如果 

Hi,

I have a scenario:I loaded my combox box with the datatable in my Form Load as below:

m_dtDelayedDeliveryDays = GetDelayedDeliveryDays()



       For Each dr As DataRow In m_dtDelayedDeliveryDays.Rows
           Me.cmbDelayedDeliveryDays.Items.Add(dr("DeliveryDelayDays"))
       Next

       cmbDelayedDeliveryDays.DataSource = m_dtDelayedDeliveryDays
       cmbDelayedDeliveryDays.DisplayMember = "DeliveryDelayDays"
       cmbDelayedDeliveryDays.ValueMember = "DeliveryDelayDaysID"

In also i am able to pick the Id based on the user selection as below:

Private Sub cmbDelayedDeliveryDays_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbDelayedDeliveryDays.SelectedIndexChanged

        cmbDelayedDeliveryDays.Refresh()
        Dim selectedDataRow As DataRow = DirectCast(cmbDelayedDeliveryDays.SelectedItem, DataRowView).Row
        Dim delayId As Integer = Convert.ToInt32(selectedDataRow("DeliveryDelayDaysID"))


    End Sub

My combo box is loaded with values like 0,3,7,15,20,30..
With the above code my combo box is with default value 0. I want me combo box to be empty by default.

Please help.

Thanks.

解决方案

After

cmbDelayedDeliveryDays.ValueMember = "DeliveryDelayDaysID"

put the following

cmbDelayedDeliveryDays..SelectedIndex = -1

In Sub cmbDelayedDeliveryDays_SelectedIndexChanged you need to wrap any code that refers to cmbDelayedDeliveryDays.SelectedItem with a check on

.SelectedIndex

e.g.

If cmbDelayedDeliveryDays.SelectedIndex > 0 Then
     Debug.Print(cmbDelayedDeliveryDays.SelectedValue.ToString())
End If

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