在與多個父實體記錄相關的DataGridView控件中顯示子數據

Question

我有一個帶有三個BindingSource控件的VB winforms窗體，每個控件顯示通過DB First創建的三個相關實體的數據（通過DataGridView或綁定的文本框）。

我需要有一個datagridview顯示和允許添加/編輯/刪除只tbl_Distribution_DealerModel_OverAlts那大部分都與當前記錄tbl_PrimaryDealerGroup記錄（加盟上田tbl_PrimaryDealerGroup.DealerGroupID = tbl_Distribution_DealerModels_OverAlts.FirstDealerGroupID ）和當前tbl_SeriesManufacturer記錄（連接在兩個公共字段： aus_series_cde和ManufacturerID ）。 tbl_Distribution_DealerModel_OverAlts位於與其他兩個表的關系的多方面：

如何讓子實體的datagridview只顯示與兩個（或更多）父實體記錄中的每一個相關的記錄？ 在這個項目中，我可能也有必要將一個孩子實體與三個或三個以上的父母聯系起來，因此可以得到普遍適用的答案

Answer 1

我終於自己解決了這個問題：

Private Sub bs_tblSM_tblPDG_CurrentChanged(sender As System.Object, e As System.EventArgs) Handles bs_tbl_Series_Manufacturer.CurrentChanged, bs_tbl_PrimaryDealerGroup.CurrentChanged
    If bs_tbl_Series_Manufacturer.Current IsNot Nothing And bs_tbl_PrimaryDealerGroup.Current IsNot Nothing Then
        Dim Series As String = bs_tbl_Series_Manufacturer.GetItemProperties(Nothing)("aus_series_cde").GetValue(bs_tbl_Series_Manufacturer.Current)
        Dim Manufacturer As Byte = bs_tbl_Series_Manufacturer.GetItemProperties(Nothing)("ManufacturerID").GetValue(bs_tbl_Series_Manufacturer.Current)
        Dim PDG As Integer = bs_tbl_PrimaryDealerGroup.GetItemProperties(Nothing)("DealerGroupID").GetValue(bs_tbl_PrimaryDealerGroup.Current)
        Dim ChangeFilter As Boolean = False
        If m_CurrentSeries <> Series Then
            m_CurrentSeries = Series
            ChangeFilter = True
        End If
        If m_CurrentManufacturer <> Manufacturer Then
            m_CurrentManufacturer = Manufacturer
            ChangeFilter = True
        End If
        If m_CurrentPDG <> PDG Then
            m_CurrentPDG = PDG
            ChangeFilter = True
        End If
        If ChangeFilter Then
            Dim DlrMdlOverAlts As IEnumerable(Of tbl_Distribution_DealerModel_OverAlts)
            DlrMdlOverAlts = From DDMOA As tbl_Distribution_DealerModel_OverAlts In m_Context.tbl_Distribution_DealerModel_OverAlts.Local.ToBindingList _
                             Where DDMOA.aus_series_cde = m_CurrentSeries And DDMOA.ManufacturerID = m_CurrentManufacturer And DDMOA.FirstDealerGroupID = m_CurrentPDG _
                             Select DDMOA
            bs_tbl_Distribution_DealerModel_OverAlts.DataSource = DlrMdlOverAlts.ToList
            Me.dgvtbcDealerModelOverAlts_aus_series_cde.DefaultCellStyle.NullValue = m_CurrentSeries.ToString
            Me.dgvtbcDealerModelOverAlts_ManufacturerID.DefaultCellStyle.NullValue = m_CurrentManufacturer.ToString
            Me.dgvtbcDealerModelOverAlts_FirstDealerGroupID.DefaultCellStyle.NullValue = m_CurrentPDG.ToString
            bs_tbl_Distribution_DealerModel_OverAlts.ResetBindings(False)
            ChangeFilter = False
        End If
    End If
End Sub

訣竅是不要嘗試在子BindingSource的子BindingSource使用父BindingSource的DataMember ，而要在兩個父BindingSource的CurrentChanged中的代碼中關聯實體。