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Re: Can DBI modify queries on the fly?

by perrin (Chancellor)
on Feb 17, 2009 at 23:42 UTC ( #744594=note: print w/replies, xml ) Need Help??

in reply to Can DBI modify queries on the fly?

You could use DBI callbacks.

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Re^2: Can DBI modify queries on the fly?
by kyle (Abbot) on Feb 18, 2009 at 02:07 UTC

    Wow, I wish that were more documented. I haven't tried it yet, but I suspect that will work great. My main concern comes from this line of the tests:

    is ref $attr, 'HASH', 'param modified by callback - not recommended!';

    Modifying params by callback is exactly what I want to do. So why is it not recommended? I'm guessing this means that the solution I eventually come up with will stop working at some point in the future, but I guess I'll curse that bridge when I come to it.

      That refers to modifying @_ only, not modifying copies of what's in @_ or SQL placeholders

        That's kind of the whole point, though, isn't it? The callback can't return any values. The only way to make any changes to what's going on is to modify the parameters directly. Or am I missing something?

        As such, you have to worry about changing the application's data under its nose. You also have to watch out for the case where you're passed a read-only value.

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