Question

当我尝试绑定到文本框以分离BindingContexts（通过容器控件，如GroupBox）时，我遇到了问题。文本框不显示绑定值。（此示例基于bindingcontext文档here）

以下是代码：

Dim ds As New DataSet1

Public Sub New()
    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.
    BindControls()
    GetData()
End Sub

Private Sub BindControls()
    Dim bcG1 As New BindingContext()
    Dim bcG2 As New BindingContext()

    GroupBox1.BindingContext = bcG1
    'GroupBox2.BindingContext = bcG2

    TextBox1.DataBindings.Add("Text", ds, "Orders.OrderKey")    ' groupbox1
    TextBox2.DataBindings.Add("Text", ds, "Orders.OrderKey")    ' groupbox2
    TextBox3.DataBindings.Add("Text", ds, "Orders.OrderKey")    ' form
End Sub

当我运行表单Textbox3（在表单级别）和textbox2（在GroupBox2中）按预期同步时，TextBox2显示OrderKey的值。但是，Textbox1（在GroupBox1中）不显示任何值。我已经确定GroupBox1确实使用了单独的BindingContext，并且位置命令确实移动到独立于表单的新行。如果我注释掉设置GroupBox1的BindingContext，它的行为就像Texbox2一样，在表单级别同步。如果我取消注释设置Groupbox2的BindingContext，它的行为与Textbox1不同步，但不会在文本框中显示任何值。

有人能看到我失踪的东西吗？

以下是完整代码：

Imports System
Imports System.Data
Imports System.Data.SqlClient

Public Class Form1

Dim ds As New DataSet1

Public Sub New()
    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.
    BindControls()
    GetData()
End Sub

Private Sub BindControls()
    Dim bcG1 As New BindingContext()
    Dim bcG2 As New BindingContext()

    GroupBox1.BindingContext = bcG1
    'GroupBox2.BindingContext = bcG2

    TextBox1.DataBindings.Add("Text", ds, "Orders.OrderKey")    ' groupbox1
    TextBox2.DataBindings.Add("Text", ds, "Orders.OrderKey")    ' groupbox2
    TextBox3.DataBindings.Add("Text", ds, "Orders.OrderKey")    ' form
End Sub

' ** groupbox1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    GroupBox1.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(GroupBox1.BindingContext(ds, "Orders").Current, DataRowView)
    TextBox5.Text = drv("OrderKey")
End Sub

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    GroupBox1.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(GroupBox1.BindingContext(ds, "Orders").Current, DataRowView)
    TextBox5.Text = drv("OrderKey")
End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    GroupBox2.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(GroupBox2.BindingContext(ds, "Orders").Current, DataRowView)
    TextBox6.Text = drv("OrderKey")
End Sub


' ** groupbox2
Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
    GroupBox2.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(GroupBox2.BindingContext(ds, "Orders").Current, DataRowView)
    TextBox6.Text = drv("OrderKey")
End Sub

Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
    Me.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(Me.BindingContext(ds, "Orders").Current, DataRowView)
    TextBox4.Text = drv("OrderKey")
End Sub

' ** Form
Private Sub Button6_Click(sender As Object, e As EventArgs) Handles Button6.Click
    Me.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(Me.BindingContext(ds, "Orders").Current, DataRowView)
    TextBox4.Text = drv("OrderKey")
End Sub

Private Sub GetDataButton_Click(sender As Object, e As EventArgs) Handles GetDataButton.Click
    GetData()
End Sub

Public Sub GetData()
    ds.Clear()
    Dim ota As New DataSet1TableAdapters.OrdersTableAdapter
    ota.Adapter.SelectCommand = New SqlCommand("SELECT OrderKey, CustomerFK, OrderDate, DeliveryMethod, Special_Instr, " & _
            "TotalOrderAmount " & _
            "FROM Orders ", ota.Connection)
    ota.Adapter.Fill(ds)
End Sub
End Class

Answer 1

微软此时拒绝解决错误报告，但我确实发现我可以使用BindingSource来完成我想要做的事情。重要说明：要设置过滤器，需要将BindingSource.DataSource属性设置为新的DataView。默认情况下，它使用DataTable的默认视图，因此在BindingSource的一个实例上设置过滤器会将其设置为另一个实例。 DataSource赋值与此类似：

BindingSource1.DataSource = New DataView（DataSource1.DataTable1）

以下是修订后的代码：

Imports System

导入System.Data Imports System.Data.SqlClient

公共类Form1BindingSource

Dim ds As New DataSet1
Dim bsForm As BindingSource
Dim bsG1 As BindingSource
Dim bsG2 As BindingSource
Dim BindingSource1 As BindingSource

Private _OcConnectionString As String
Public Property OcConnectionString() As String
    Get
        Return _OcConnectionString
    End Get
    Set(ByVal value As String)
        _OcConnectionString = value
    End Set
End Property

Public Sub New()
    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.
    BindControls()
    GetData()
End Sub

Public Sub New(strConnection As String)
    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.
    OcConnectionString = strConnection
    BindControls()
    GetData()
End Sub

Private Sub BindControls()

    bsForm = New BindingSource
    bsG1 = New BindingSource
    bsG2 = New BindingSource

    bsForm.DataSource = ds
    bsG1.DataSource = ds
    bsG2.DataSource = ds

    bsForm.DataMember = "Orders"
    bsG1.DataMember = "Orders"
    bsG2.DataMember = "Orders"

    'BindingSource1 = New BindingSource(ds, "Orders")
    BindingSource1 = New BindingSource
    BindingSource1.DataSource = ds
    BindingSource1.DataMember = "Orders"
    Me.DataGridView1.DataSource = BindingSource1

    TextBox1.DataBindings.Add("Text", bsG1, "OrderKey")    ' groupbox1
    TextBox2.DataBindings.Add("Text", bsG2, "OrderKey")    ' groupbox2
    TextBox3.DataBindings.Add("Text", BindingSource1, "OrderKey")    ' form
    TextBox8.DataBindings.Add("Text", BindingSource1, "OrderKey")    ' Groupbox3

End Sub

' ** groupbox1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    bsG1.MovePrevious()
    'GroupBox1.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(bsG1.Current, DataRowView)
    TextBox5.Text = drv("OrderKey")
End Sub

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    bsG1.MoveNext()
    'GroupBox1.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(bsG1.Current, DataRowView)
    TextBox5.Text = drv("OrderKey")
End Sub

' ** groupbox2
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    bsG2.MovePrevious()
    'GroupBox2.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(bsG2.Current, DataRowView)
    TextBox6.Text = drv("OrderKey")
End Sub

Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
    bsG2.MoveNext()
    'GroupBox2.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(bsG2.Current, DataRowView)
    TextBox6.Text = drv("OrderKey")
End Sub

'** form level
Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
    bsForm.MovePrevious()
    'Me.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(bsForm.Current, DataRowView)
    TextBox4.Text = drv("OrderKey")
End Sub

Private Sub Button6_Click(sender As Object, e As EventArgs) Handles Button6.Click
    bsForm.MoveNext()
    'Me.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(bsForm.Current, DataRowView)
    TextBox4.Text = drv("OrderKey")
End Sub

'** Groupbox3
Private Sub Button8_Click(sender As Object, e As EventArgs) Handles Button8.Click
    bsForm.MovePrevious()
    'GroupBox3.BindingContext(ds, "Orders").Position -= 1
    Dim drv As DataRowView = CType(bsForm.Current, DataRowView)
    TextBox8.Text = drv("OrderKey")
End Sub

Private Sub Button7_Click(sender As Object, e As EventArgs) Handles Button7.Click
    bsForm.MoveNext()
    'GroupBox3.BindingContext(ds, "Orders").Position += 1
    Dim drv As DataRowView = CType(bsForm.Current, DataRowView)
    TextBox8.Text = drv("OrderKey")
End Sub

Private Sub GetDataButton_Click(sender As Object, e As EventArgs) Handles GetDataButton.Click
    GetData()
End Sub

Public Sub GetData()
    Try
        Dim ota As New DataSet1TableAdapters.OrdersTableAdapter
        If OcConnectionString IsNot Nothing Then
            ota.Connection.ConnectionString = OcConnectionString
        End If
        ds.Clear()
        ota.Adapter.SelectCommand = New SqlCommand("SELECT OrderKey, CustomerFK, OrderDate, DeliveryMethod, Special_Instr, " & _
                "TotalOrderAmount " & _
                "FROM Orders ", ota.Connection)
        ota.Adapter.Fill(ds)
    Catch exp As Exception
        MsgBox(exp.Message)
    End Try
End Sub

结束班

卡尔

使用父控件的TextBoxes BindingContexts不显示数据值

1 个答案: