绑定的datatgridview没有将更改保存到表适配器，因此也没有保存到数据库

Question

我有一个数据网格视图绑定到一个表，该表似乎工作正常，但不会保存对数据库的更改。我使用的代码与我在另一个项目中使用的代码相同，该项目确实保存了更改，所以我很困惑。此外，我已经调试好了，保存代码正在被调用，只是不起作用。表单中的代码使用业务逻辑调用一个单独的类。

代码格式如下：

Private Sub frmAdminAssign_Load(sender As Object, e As EventArgs) Handles MyBase.Load
' Below is generated by Visual Studio when I select my data source for my datagridview
Credit_adminTableAdapter.Fill(DataSet1.credit_admin) ' Foreign key relationship to table being updated (lookup table).
LoanTableAdapter.Fill(DataSet1.loan) ' Table being updated
admin_assign = New AdminAssign()
admin_assign.FilterUnassigned(dgvAssign, LoanTableAdapter)
End Sub
Private Sub dgvAssign_CellEndEdit(sender As Object, e As DataGridViewCellEventArgs) Handles dgvAssign.CellEndEdit
admin_assign.SaveAssignmentChanges(DataSet1, LoanTableAdapter)
End Sub

下面是从上面调用的业务逻辑类中的代码：

Public Sub SaveAssignmentChanges(ByRef data_set As DataSet1, ByRef loan_table_adapter As DataSet1TableAdapters.loanTableAdapter)
' Saves changes to DB.
Dim cmdBuilder As SqlCommandBuilder
cmdBuilder = New SqlCommandBuilder(loan_table_adapter.Adapter)
loan_table_adapter.Adapter.UpdateCommand = cmdBuilder.GetUpdateCommand(True)
Try
loan_table_adapter.Adapter.Update(data_set)
Catch unknown_ex As Exception
Dim error_title As String = "Database Save Error"
Dim unknown_error As String = $"There was an error saving to the database.{vbNewLine}Error: {unknown_ex.ToString}"
MessageBox.Show(unknown_error, error_title, MessageBoxButtons.OK, MessageBoxIcon.Warning)
End Try
End Sub

datagridview中的数据没有保存到tableadapter中，这是我在第二个过程开始时添加以下行发现的：

Dim x As String = loan_table_adapter.GetData()(0)("note_number") ' Unchanged, check was right row
Dim y As String = loan_table_adapter.GetData()(0)("credit_admin_id") ' Changed in datagridview but still null (get null error)

Answer 1

我发现了这一点，它与一个过滤器例程有关，该例程不高于我传递表适配器byref的位置，而我本应传递数据表byval。因此，与上面jmcilinney的byref对byval的评论有关。请参阅下面的问题代码：

Public Sub FilterUnassigned(ByRef dgv_assigned As DataGridView, loan_table_adapter As DataSet1TableAdapters.loanTableAdapter)
' Should have passed in DataSet1.loan DataTable ByVal and used it below:
Dim unassigned_loans As DataView = loan_table_adapter.GetData().DefaultView()
unassigned_loans.RowFilter = "request_date Is Not Null AND numerated_assigned_user Is Null"
dgv_assigned.DataSource = unassigned_loans
End Sub

此外，跳过SQLCommandBuilder命令和我的代码仍然有效。所以，我只需要一行jmcilinney，而不是4行(不包括错误处理(如下：

Try
loan_table_adapter.Update(data_set)
Catch unknown_ex As Exception
Dim error_title As String = "Database Save Error"
Dim unknown_error As String = $"There was an error saving to the database.  Please contact Kevin Strickler to resolve.{vbNewLine}Error: {unknown_ex.ToString}"
MessageBox.Show(unknown_error, error_title, MessageBoxButtons.OK, MessageBoxIcon.Warning)
End Try