How to validate DBGrid fields before saving?

Doing this in the TDataSet.BeforePost event is not a bad idea, however as you want to validate the fields in specific, the event DB.TField.OnValidate may best suit this case.

To use this event do:

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

  

• Inthenextwindowselectthefieldthatyouwanttovalidate.

• IntheObjectInspector,gototheEventstabanddoubleclickonOnValidate.

Now you just have to validate the field, redo the same process for the other required fields. So when the user edit such a field, before the change is saved, OnValidate is called.

For example, if I want to prevent the user from saving the Animal field the giraffe field,

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