delphi - 字段 'Invoice_Date' 无法修改

Question

我有以下 ms access 2003 表:

Invoice_Master
(
   Invoice_Id  Autonumber,
   Customer_Id  integer,
   Invoice_Date  Date/Time not null,
.
.
.
);

和以下代码(Delphi 7)

procedure TfmInvoiceMaster.adoMasterEditNewRecord(DataSet: TDataSet);
begin
  inherited;
  adoMasterEditInvoice_Date.AsDateTime := Date;
end;

当我尝试添加新记录时，我以异常错误 sys 结束:

Field 'Invoice_Date' cannot be modified.

请问有什么问题

Answer 1

你这样做是错的。 :)

您应该使用 AfterEdit事件代替。来自 TDataSet.AfterEdit 上的帮助文件:

Write an AfterEdit event handler to take specific action immediately after dataset enters edit mode. AfterEdit is called by Edit after it enables editing of a record, recalculates calculated fields, and calls the data event handler to process a record change.

像这样使用它:

procedure TfmInvoiceMaster.adoMasterAfterEdit(DataSet: TDataSet);
begin
  // No inherited call! This is an event handler, not an overridden method
  adoMasterEditInvoice_Date.AsDateTime := Date;
end;

但是，从您的文本中，您似乎想要在插入记录时执行此操作，而不是进行编辑(“当我尝试添加新记录时，我以异常错误 sys:”结束)。如果是这种情况，请使用 AfterInsert完全相同的方式:

procedure TfmInvoiceMaster.adoMasterAfterInsert(DataSet: TDataSet);
begin
  // No inherited call! This is an event handler, not an overridden method
  adoMasterEditInvoice_Date.AsDateTime := Date;
end;