源查询无结果时，如何访问Form.Textbox.Text属性？

我正在制作一个连续表单用于搜索，用户在多个搜索框中输入内容时，表单会自动更新。
在用户输入对应无匹配记录的参数前，代码运行正常。

当查询无结果时，我会收到以下错误提示：

"Can't use the property or method when the control doesn't have the focus"

我无法确定是表单中的哪个元素导致的问题，为文本框控件添加.SetFocus方法也没有效果。

请问有什么办法可以：

1. 重新为文本框设置焦点并防止焦点丢失；或者
2. 找出窃取焦点的元素并禁用它？

以下是在textbox_Change子过程中调用的RefreshTB子过程，我已添加了一个临时解决方法：

Private Sub RefreshTB(textbox As Control)
    'This is to prevent Acces from removing trailing spaces
    'If the textbox isn't empty and there is a space at the end, don't requery. This preserves trailing spaces as Access trims them on Me.requery
    If Len(textbox.Text) <> 0 And InStr(Len(textbox.Text), textbox.Text, " ", vbTextCompare) Then
        Exit Sub
    End If
    'If the last character isn't a space, requery on change to show new results of the query
    Me.Requery
    'The workaround: If the query returns no results, detect that, warn the user and clear search box. Requery to show some results again.
    If DCount("*", "DatasetsFilterQ") = 0 Then
        If MsgBox("No results found. The last TextBox you searched in will be cleared.", vbOKOnly, "No Records") = vbOK Then
            textbox = ""
            Me.Requery
        End If
        Exit Sub
    End If
    textbox.SetFocus
    textbox.SelStart = Len(Nz(textbox.Text))
End Sub

我尝试过使用过滤器，但在将.Text值传递给函数时遇到了相同的错误。

解决方案一：修正焦点设置逻辑 #

问题核心是Me.Requery执行后，无记录的连续表单会自动将焦点转移到导航按钮、空记录行控件等元素，导致原文本框失去焦点，后续.SetFocus因控件状态失效。调整代码如下：

Private Sub RefreshTB(textbox As Control)
    Dim txtName As String
    txtName = textbox.Name ' 提前记录文本框名称，避免控件对象失效
    
    ' 保留原尾空格判断逻辑
    If Len(textbox.Text) <> 0 And InStr(Len(textbox.Text), textbox.Text, " ", vbTextCompare) Then
        Exit Sub
    End If
    
    Me.Requery
    
    If DCount("*", "DatasetsFilterQ") = 0 Then
        If MsgBox("No results found. The last TextBox you searched in will be cleared.", vbOKOnly, "No Records") = vbOK Then
            Me(txtName) = ""
            Me.Requery
            DoEvents ' 等待表单状态更新完成
            ' 用控件名称重新设置焦点
            Me(txtName).SetFocus
            Me(txtName).SelStart = Len(Nz(Me(txtName).Text))
        End If
        Exit Sub
    End If
    
    DoEvents
    Me(txtName).SetFocus
    Me(txtName).SelStart = Len(Nz(Me(txtName).Text))
End Sub

解决方案二：定位并禁用抢焦点元素 #

通过日志记录焦点变化，找到窃取焦点的控件：

1. 在表单模块添加全局变量：

Private lastFocusedControl As String

2. 为表单添加焦点日志事件：

Private Sub Form_GotFocus()
    lastFocusedControl = Me.ActiveControl.Name
    Debug.Print "焦点转移到：" & lastFocusedControl ' 按Ctrl+G打开立即窗口查看日志
End Sub

触发无结果查询后，查看立即窗口记录的控件名称，针对性处理：

• 若为导航按钮：在表单属性中设置NavigationButtons = No
• 若为空记录行控件：设置控件TabStop = No，或无记录时隐藏
• 若为其他控件：无结果时设Enabled = False，有结果时恢复

额外建议：用Filter替代Requery减少焦点异常 #

频繁Requery会导致表单频繁刷新，改用Filter可避免重新加载表单，更易保持焦点：

Private Sub RefreshTB(textbox As Control)
    Dim txtName As String
    txtName = textbox.Name
    Dim filterStr As String
    
    ' 根据你的查询逻辑构建过滤条件
    filterStr = "[目标字段名] Like '*" & Replace(textbox.Text, "'", "''") & "*'"
    
    ' 保留尾空格判断
    If Len(textbox.Text) <> 0 And InStr(Len(textbox.Text), textbox.Text, " ", vbTextCompare) Then
        Me.Filter = filterStr
        Me.FilterOn = True
        Exit Sub
    End If
    
    Me.Filter = filterStr
    Me.FilterOn = True
    
    If Me.Recordset.RecordCount = 0 Then
        If MsgBox("No results found. The last TextBox you searched in will be cleared.", vbOKOnly, "No Records") = vbOK Then
            Me(txtName) = ""
            Me.Filter = ""
            Me.FilterOn = False
            DoEvents
            Me(txtName).SetFocus
        End If
        Exit Sub
    End If
    
    DoEvents
    Me(txtName).SetFocus
    Me(txtName).SelStart = Len(Nz(Me(txtName).Text))
End Sub

内容的提问来源于stack exchange，提问作者T00Fast