I have something like so:

```
 CELL #0      CELL #1
------------------------
|start_date | end_date |
|----------------------|
|1/1/2012   |1/1/2013  |  ROW#0
|----------------------|

```

I would like to assert that if the user clicks on (Row0,Cell0) and tries to change the start date, then the start date has to be less than the end date else the changes are not put through. Is this possible?

Currently when creating the columns, I add a 'validator' property and pass in the function below

```
startDateValidator(value){ 
   /* value is new value, need to reference the end_date to make sure
      that value < end_date but not possible in this column validator */
}

```

but as the comment points out, we are given the new value but no reference to the old data-item. Is there a way to get around this? I can change the source, but would want to avoid if possible.