组合框 KeyDown 事件处理程序多次触发
在 VB.NET 中，我在 WinForm 窗体上有一个组合框。 该表单允许用户输入要搜索的查询。 当用户按下 Enter 键时，将对数据库执行查询，并将结果作为 DataTable 返回。 然后，数据表绑定到组合框，用户可以选择他们正在查找的选项。
在大多数情况下，这非常有效。 然而，我们发现该代码被执行了多次。 如果我写出查询并按一次 Enter 键，我可以单步执行代码两到三次。 如果不需要，我不想多次向数据库发送相同的查询。 为什么代码会执行多次有什么想法或建议吗？
这是有问题的代码。 组合框和函数名称已更改以保护无辜者。 :)
Private Sub cbx_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles cbx.KeyDown
Me.Cursor = Cursors.IBeam
If e.KeyData = Keys.Enter Then
Me.Cursor = Cursors.WaitCursor
PerformSearch()
Me.Cursor = Cursors.Default
End If
Me.Cursor = Cursors.Default
End Sub
In VB.NET, I have a Combobox on a WinForm form. The form allows the user to type in a query to be searched. When the user hits the Enter key, a query is performed against the database and the results are returned as a DataTable. The DataTable is then bound to the Combobox and the user can select the option that they are looking for.
For the most part, this is working great. However, we've discovered that the code is executing multiple times. If I write my query out and hit the Enter key ONCE, I can step through the code TWO or THREE times. I don't want to send the same query to the database multiple times if I do not have to. Any ideas or suggestions why the code would be executing multiple times?
Here is the code in question. The Combobox and Function names have been changed to protect the innocent. :)
Private Sub cbx_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles cbx.KeyDown
Me.Cursor = Cursors.IBeam
If e.KeyData = Keys.Enter Then
Me.Cursor = Cursors.WaitCursor
PerformSearch()
Me.Cursor = Cursors.Default
End If
Me.Cursor = Cursors.Default
End Sub
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具有讽刺意味的是，在执行搜索后添加 cbx.Focus() 解决了问题。 这是解决方案。
Ironically, adding cbx.Focus() after the search has been performed fixed the problem. Here is the solution.