Question

我有一个表SampleData，它有一个子表，Measurements。在我的WinForm，frmMain上，一个SampleData对象绑定到SampleDataBindingSource; MeasurementsBindingSource将SampleDataBindingSource作为其数据源，将Measurements作为其DataMember。一组文本框绑定到SampleDataBindingSource; datagridview绑定到MeasurementsBindingSource。

对于frmMain，我还有一个presen类，preMain，它包含一个SampleData类型的属性CurrentSample。 SampleDataBindingSource.DataSource绑定到preMain的CurrentSample属性。

当分配了测量中的足够属性时，它会计算FiringFactor，如果FiringFactor不是1，它会将另一个Measurement项添加到CurrentSample的Measurement实体集中：

Partial Class Measurement

    Private Sub UpdateFiringFactor()
        Dim necessaryDataIsAvailable As Boolean = (Me.CrucibleMass IsNot Nothing And _
                                                   Me.CrucibleSampleFiredMass IsNot Nothing And _
                                                   Me.CrucibleSampleMass IsNot Nothing)
        If necessaryDataIsAvailable Then
            Me.FiringFactor = CDbl((Me.CrucibleSampleFiredMass - Me.CrucibleMass) / (Me.CrucibleSampleMass - Me.CrucibleMass))
            If Me.FiringFactor <> 1 Then
                Me.SampleData.AddNewMeasurement()
            End If
        End If
    End Sub

    Private Sub OnCrucibleMassChanged()
        UpdateFiringFactor()
    End Sub


    Private Sub OnCrucibleSampleFiredMassChanged()
        UpdateFiringFactor()
    End Sub


    Private Sub OnCrucibleSampleMassChanged()
        UpdateFiringFactor()
    End Sub
End Class

当我在datagridview中输入CrucibleMass，CrucibleSampleMass和CrucibleSampleFiredMass的值时，UpdateFiringFactor方法确实正确运行，我最终将另一个Measurement项添加到CurrentSample的Measurements实体集中。但是，datagridview不显示新行，MeasurementsBindingSource只有1条记录（但CurrentSample.Measurements.Count = 2）。

为什么CurrentSample.Measurements中的更改不会传播到MeasurementsBindingSource？我尝试了MeasurementsBindingSource.ResetBindings(False)，MeasurementsDataGridView.Refresh，SampleDataBindingSource.ResetBindings(False)，但似乎没有更新MeasurementsBindingSource或其datagridview。

Answer 1

这是我在entityset / bindingsource问题中找到的解决方案：

Imports System.ComponentModel

Partial Class Measurement

    Public Sub ChangeCrucibleMass(ByVal thisMass As Double)
        CrucibleMass = thisMass
        UpdateFiringFactor()
    End Sub

    Public Sub ChangeCrucibleSampleMass(ByVal thisMass As Double)
        CrucibleSampleMass = thisMass
        UpdateFiringFactor()
    End Sub

    Public Sub ChangeCrucibleSampleFiredMass(ByVal thisMass As Double)
        CrucibleSampleFiredMass = thisMass
        UpdateFiringFactor()
    End Sub

    Private Sub UpdateFiringFactor()
        If AllDataAreAvailable() Then
            FiringFactor = (CrucibleSampleFiredMass - CrucibleMass) / (CrucibleSampleMass - CrucibleMass)
            Me.Sample.OnMeasurementsChanged(Nothing, Nothing)
        End If
    End Sub

    Private Function AllDataAreAvailable() As Boolean
        AllDataAreAvailable = False
        Dim allFieldsHaveValue As Boolean = (CrucibleMass IsNot Nothing And CrucibleSampleFiredMass IsNot Nothing And CrucibleSampleMass IsNot Nothing)
        If allFieldsHaveValue Then
            Dim denominatorIsNotZero As Boolean = (CrucibleSampleMass - CrucibleMass) <> 0
            Return denominatorIsNotZero
        End If

    End Function

End Class

Partial Class Sample

    Public Sub OnMeasurementsChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Handles Me.PropertyChanged
        If Me.Measurements.Count > 0 AndAlso Me.Measurements.Last.FiringFactor IsNot Nothing AndAlso Me.Measurements.Last.FiringFactor <> 1 Then
            Me.Measurements.Add(New Measurement With {.CrucibleMass = Me.Measurements.Last.CrucibleMass})
            RaiseEvent RefreshMeasurementsBinding()
        End If
    End Sub

    Private Sub OnCreated()
        Me.Measurements.Add(New Measurement)
    End Sub

    Public Event RefreshMeasurementsBinding()

End Class

以下是表单的截图：

enter image description here

代码隐藏：

Imports System.ComponentModel

Public Class Form1

    Private WithEvents newSample As Sample

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        newSample = SampleConduit.GetSample(1)
        'newSample = New Sample
        Me.SampleBindingSource.DataSource = newSample
        OnRefreshMeasurementsBinding()

    End Sub

    Private Sub OnRefreshMeasurementsBinding() Handles newSample.RefreshMeasurementsBinding
        Me.MeasurementsBindingSource.DataSource = newSample.Measurements.GetNewBindingList
    End Sub


    Private Sub MeasurmentsDataGridView_CellClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles MeasurmentsDataGridView.CellClick
        Me.MeasurementsBindingSource.EndEdit()
        Dim currentMeasurement = CType(Me.MeasurementsBindingSource.Current, Measurement)
        Select Case e.ColumnIndex
            Case 0
                currentMeasurement.ChangeCrucibleMass(GetMeasurement)
            Case 1
                currentMeasurement.ChangeCrucibleSampleMass(GetMeasurement)
            Case 2
                currentMeasurement.ChangeCrucibleSampleFiredMass(GetMeasurement)
        End Select
    End Sub

    Private Function GetMeasurement() As Double
        Return CDbl(InputBox("Measurement:", "Get Measurement", "0"))
    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        Dim currentSample = CType(Me.SampleBindingSource.Current, Sample)
        SampleConduit.SaveSample(currentSample)
    End Sub
End Class

解决方案取决于Sample类中的RefreshMeasurementsBinding事件和表单中的OnRefreshMeasurementsBinding方法。经常将MeasurementsBindingSource设置为Measurements实体集上的GetNewBindingList方法似乎有些麻烦，但它可以工作。

在此论坛帖子中查看关于EntitySets和BindingSource以及GetNewBindingList的第3项：

http://www.infragistics.com/community/forums/t/43526.aspx

绑定到子实体集的子绑定源不会更新

1 个答案: