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Re^7: Class::DBI::AbstractSearch and SpeedyCGI

by zigdon (Deacon)
on Oct 05, 2005 at 02:41 UTC ( #497469=note: print w/replies, xml ) Need Help??

in reply to Re^6: Class::DBI::AbstractSearch and SpeedyCGI
in thread Class::DBI::AbstractSearch and SpeedyCGI

Hmmm. I think the I found something odd. I added three debugging lines:
C:DBI:AS:search_where: (line 31) warn "search_where"; warn Dumper ($phrase, \@bind); C:DBI:retrieve_from_sql: (line 1067) warn "retrieve_from_sql"; warn Dumper $sql, \@vals; C:DBI:sth_to_objects: (line 1125) warn "sth_to_objects"; warn Dumper $args;
At each one, I dumped out all the params being worked on. Here's what happens in the page where the problem is consistant... The page loops over multiple items, and it always breaks on the 3rd item. First iteration:
search_where - $VAR1 = '( ID = ? )'; $VAR2 = [ '3225-1' ]; retrieve_from_sql - $VAR1 = '( ID = ? )'; $VAR2 = [ '3225-1' ]; sth_to_objects - $VAR1 = [ '3225-1' ]; Attempt to free unreferenced scalar: SV 0x88020e4
Second iteration:
search_where - $VAR1 = '( ID = ? )'; $VAR2 = [ '5912-1' ]; retrieve_from_sql - $VAR1 = '( ID = ? )'; $VAR2 = [ '5912-1' ]; sth_to_objects - $VAR1 = [ '5912-1' ]; Attempt to free unreferenced scalar: SV 0x880e61c
Third iteration (and this one breaks):
search_where - $VAR1 = '( ID = ? )'; $VAR2 = [ '5913-1' ]; retrieve_from_sql - $VAR1 = '( ID = ? )'; $VAR2 = \'5913-1'; sth_to_objects - $VAR1 = \'5913-1'; MyApp::Sets can't SELECT id, id, setnumber, setrev, name, theme, year, + pcs, figs, picture, msrp, instructions, inventory FROM SETS WHERE ( ID = ? ) : Not an ARRAY reference
Looking at this, it's obvious that for some reason, the 3rd run does change from an arrayref to a scalarref. But I can't see why, or how this happens? There is _nothing_ touching that value between the 2nd debug line and the 3rd debug line. Makes me think it's some sort of thread-safe issue... Except that this particular CGI is just running plain perl - not SpeedyCGI or anything else. How can I dig deeper?

-- zigdon

Replies are listed 'Best First'.
Re^8: Class::DBI::AbstractSearch and SpeedyCGI
by perrin (Chancellor) on Oct 05, 2005 at 03:26 UTC
    It looks like an obscure case of list context biting you. Take a look at the warnings about \(@foo) in the perlref man page to see what I mean. Maybe your code is using the return value in a list context in the third spot? I would probably throw in some wantarray() checks to see if that's the difference, and maybe break out the debugger.
      Very interesting (and I'll try to see how this applies here) - but why would it only hit on the 3rd iteration, but not the first two? In all cases it was an arrayref with a single element?

      -- zigdon

        Does the code where you call this do it exactly the same every time? There may be something subtle that changes it to list context on the third one. Can you show that part?

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