delphi - How to get dbgrid cell value when you're typing? Delphi xe2

Question

The code below does not work due to the text being typing has not yet been saved:

DBGrid1.Columns [Col]. Field.AsString;

How could I get the text in the dbgrid and not directly from dataset?

The purpose of this is that I need to control what is being typed in real time.

I should not use:   onBeforePost. OnValidate onChange

Thanks!