I believe that to achieve the same, a database transaction would have
to include both the select and the update/delete.  This would include
the period of display, input and submission and the user may never
submit an update.  I hope I'm correct in this understanding but please
correct if I'm not.

The approach I am suggesting purely affects the update/delete sql
function and is intended as a light catch-all solution.

Bill

On Oct 15, 1:30 pm, achipa <[EMAIL PROTECTED]> wrote:
> In what way is this different from database transactions ?
>
> On Oct 15, 11:24 am, billf <[EMAIL PROTECTED]> wrote:
>
> > I would like to request the ability to include a column in every table
> > to be used to avoid overlapping updates, i.e. where a record has been
> > updated by user B between user A selecting a record and updating/
> > deleting it.  When this occurs user B's updates are invisibly undone.
>
> > I know that this can be hand-coded but I believe it would be a useful
> > and relatively minor addition to the core - as an option on
> > define_table? version=False being the default?
>
> > The column could be either a version_number (simpler) or a
> > last_action_timestamp (perhaps more useful but more complicated?) and
> > would be used to prevent a record being updated/deleted if it had been
> > changed since selected.  This could be achieved in SQLFORM.accepts()
> > by conditionally adding " and self.table.version==version" or similar
> > to the update and delete statements. The version (or timestamp) would
> > be handled in much the same way as 'id'.
>
> > I accept that the probability of overlapping updates is small but in a
> > business situation it is important for web2py to be rigorous as
> > possible and this approach has negligible overhead.
>
> > Do people think this is desirable, do-able or dumb?
>
> > Bill
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