[Dbix-class] Chained resultsets and WHERE operators

[Alexander Hartmaier]

Note that by swapping column and value you will lose the advantage of
bind which makes sql injection impossible.

--
Best regards, Alex


On Wed, 2010-11-10 at 06:34 +0100, Mike Raynham wrote:
> On 09/11/10 22:26, Peter Rabbitson wrote:
> >
> > -nest...? what...?
> >
> > I still don't understand how this is different from anything you've showed
> > us in the thread so far. You said you want to do:
> >
> > WHERE
> > ($start_date >= start_date AND $start_date <= end_date)
> > OR
> > ($end_date >= start_date AND $end_date <= end_date)
> >
> > In SQLA it is assumed that the lhs is a column and the rhs is a bind value
> > (this is a *generalization*, there are all kinds of exceptions, but as a
> > generalization it will suffice)
> >
> > So we rewrite this as:
> > (start_date <= $start_date AND end_date >= $start_date)
> > OR
> > (start_date <= $end_date AND end_date >= $end_date)
> >
> > So then it boils down to:
> > [
> > { start_date => { '<=', $start_date }, end_date => { '>=', $start_date } },
> > { start_date => { '<=', $end_date }, end_date => { '>=', $end_date } },
> > ]
> >
> > That's it. No -nest, no braindamage.
> >
> > Cheers
>
> Hi Peter,
>
> Thank you for you input, and your solution.  I appear to have created
> some confusion, so please let me attempt to clarify things.
>
> My original question was about chaining with an OR instead of an AND.
> You pointed out that:
>
>  > Chaining implies AND ing (tightening the condition more
>  > and more)
>
> Ronald J Kimball provided an elegant solution which you kindly
> simplified.  I thanked you both for this, and said that I liked the
> solution and that I would use it.
>
> I then mentioned that if I were to write the query manually, I would
> probably swap the column and bind values around.  This is simply because
> that way the meaning looks a little clearer to me.  I fully understand
> that in this case, it doesn't affect the query in any way.  I also
> pointed out that it would do exactly the same thing as the original query.
>
> I didn't think that it was possible (at least not easily or sensibly) to
> swap the column and bind values around when generating a search with
> DBIx::Class::Resultset, and was perfectly happy to leave it at that.
> However, your response to this was:
>
>  > I don't see why not... ? Explain what do you perceive the holdup would
>  > be.
>
>  From that, I assumed that maybe there is a way to easily swap the
> column and bind values around.  I checked the DBIx::Class::Manual::FAQ,
> and found a mention of -nest, which appeared to offer a way of doing it.
>   I didn't try it.  I was, and still am, happy to restructure my
> original query to incorporate your solution.
>
>
>
>
> Regards,
>
> Mike
>
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