绑定到子实体集的子绑定源不会更新

Question

我有一个表SampleData，它有一个子表，测量。在我的WinForm中，frmMain，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Presenter类preMain，它包含SampleData类型的属性CurrentSample。 SampleDataBindingSource.DataSource被绑定到preMain的CurrentSample属性。

当足够的测量属性的已分配，它计算FiringFactor和，如果FiringFactor不为1，它增加了一个测量项目的CurrentSample的测量EntitySet的：

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 

当我输入值对于数据网格视图中的CrucibleMass，CrucibleSampleMass和CrucibleSampleFiredMass，UpdateFiringFactor方法确实运行正常，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，而MeasurementsBindingSource只有1条记录（但是CurrentSample.Measurements.Count = 2）。

为什么CurrentSample.Measurements的变化不会传播到MeasurementsBindingSource？我试过MeasurementsBindingSource.ResetBindings(False),MeasurementsDataGridView.Refresh,SampleDataBindingSource.ResetBindings(False)，但似乎没有更新MeasurementsBindingSource或其datagridview。

Answer 1

这是我发现的EntitySet的/ BindingSource的问题的解决方案：

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 

这里的表格截图：

和代码隐藏：

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RefreshMeasurementsBinding前夕在Sample类中的nt和在窗体中的OnRefreshMeasurementsBinding方法。经常将MeasurementsBindingSource设置为Measurements实体集上的GetNewBindingList方法似乎有点不便，但它有效。

见项目＃3关于此论坛发帖EntitySets和的BindingSource和GetNewBindingList：

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