How to validate Dbgrid fields before saving?

Question

I have a DBGrid, but I want it to validate the fields before saving to the database.

I believe I have to use the event BeforePost but I have no idea how to do it. Someone could give me a hint?

Answer 1

Do this at the event TDataSet.BeforePost not a bad idea, but how do you want to validate the fields in particular, the event DB.TField.OnValidate can serve better for this case.

To use this event do:

• Right-click on the AdoTable (or equivalent) and click on the first option, Fields Editor.

  

• In the next window select the field you want to validate.

• In the Object Inspector, go on the tab Events and double click on OnValidate.

  

Now all you have to do is validate the field, remake the same process for the other required fields. So when the user edits such a field, before the change is saved, the OnValidate is called.

For example, if I want to prevent the user from saving in the field Animal the word giraffe, can do:

procedure TForm1.TblAnimaisAnimalValidate(Sender: TField);
begin
if Sender.AsString = 'girafa' then
   Abort;
end;
end;