Question

我正在尝试编写一个通用例程来填充表单加载时的组合框。我从MySql获取数据并填充组合框，但它不适用于组框内的任何组合框。尝试传递formname，groupbox名称，comboname byVal和byRef，尝试传入作为对象，字符串，控件，尝试各种ctypes和trycast，似乎无法找到神奇的语法。我有一个包含2个组合框的测试表单，一个在外部，一个在groupbox和此代码中。

Public Function TESTloadComboBoxOrHelp(ByRef formName As Form, ByVal boxName As Object, ByVal callingName As String) ', ByVal groupBx)
    'loadComboBoxOrHelp(me,"comboboxname",me.name)
    'tried passing byVal and byRef, no difference
    'frmCmbTest has 2 combo boxes, one in a groupbox and one not in groupbox, the one NOT in works
    '
    If formName.Name.ToString = "frmCmbTest" Then
        CType(formName.Controls(boxName), ComboBox).Items.Add("ABC") '  1: this WORKS because combobox1 is NOT in a groupbox BUT does not work for combobox2 in groupbox
        frmCmbTest.ComboBox2.Items.Add("ZYZ") ' 2: NOT Generic, this WORKS even though combobox2 is in a groupbox so why does line 1: above NOT work for a groupbox ?
        'formName.boxName.Items.Add("ZYZ")    ' 2.1: this does NOT work even though its the equivalent syntax (didn't expect it to)
        'formName.groupBx.boxName.Items.Add("ZYZ")    ' 2.2: NOPE, Tried passing in the name of the groupbox
        'frmCmbTest.CType(formName.controls("Groupbox1"), GroupBox),CType(formName.Controls.boxName.Name.ToString), ComboBox).Items.Add("DEF") ' 3: so of course this should not work, tried to replicate line above (2:) could not figure out syntax that would work.
        'frmCmbTest.GroupBox1.ComboBox2.Items.Add("ZYZ") ' 4: does not work, as is expected not to.
        'TryCast(formName."GroupBox1".Controls(boxName.Name), ComboBox).Items.Add("MNO") '5: I am guessing I need to add the groupbox name somewhere
        TryCast(formName.Controls(boxName), ComboBox).Items.Add("MNO")  ' 6: out of ideas, works for combobox1 not in groupbox, does not work for combobox2 in groupbox1
    End If
    Return 1
End Function

目前我有5个函数，一个用于填充不在各种形式的groupbox中的组合框的通用函数和4个非通用的函数，它让我疯狂。

Answer 1

您正在处理2个不同的ControlCollections，因为看起来您使用的是Windows窗体，Control Colllection有一个Find方法，用于检查项目是否在父集合及其子集中。它将返回所有匹配项的数组，因此请确保您的设备名称是唯一的，而不是彼此的子集。 即。 boxName和boxName1搜索boxName，为您提供包含2个项目的结果

Dim c As Control() = Controls.Find("boxName", True) 'Search for boxName in parent and all child controls
If c.Count > 0 Then                                 'Check to see if we got a match
    CType(c(0), ComboBox).Items.Add("ABC")
End If

Answer 2

根据我对马克的评论，他的回答是有效的！这就是我最终的结果（供将来参考）

    Public Function TESTloadComboBoxOrHelp(ByRef formName As Form, ByVal boxName As Object, ByVal callingName As String) ', ByVal groupBx)
    'loadComboBoxOrHelp(me,"comboboxname",me.name)
    '
    Dim c As Control() = formName.Controls.Find(boxName, True) 'Search for boxName in parent and all child controls
    If c.Count > 0 Then                                 'Check to see if we got a match
        Try
            conn.Open()
            myCommand.Connection = conn
            Dim query = "SELECT name, lookupValue " _
                    & "FROM lookups " _
                    & "WHERE name = '" & formName.Name.ToString & "." & boxName.ToString & "'"
            myCommand.CommandText = query
            If debug Then evl.WriteToSimpleLog(query, callingName)
            myReader = myCommand.ExecuteReader()
            While myReader.Read
                CType(c(0), ComboBox).Items.Add(myReader.GetString("lookupValue").ToString)
            End While
        Catch ex As Exception
            MessageBox.Show("Error while retrieving records on table Lookups..." & ex.Message, "Lookups Table")
        Finally
            If conn.State = ConnectionState.Open Then conn.Close()
        End Try
    End If

我也会尝试建议的数据绑定，我只是没有想到，但这终于有效了，我讨厌我一直在使用的解决方法

当组合框位于组合框中时，在vbnet中填充组合框

2 个答案: