Bug #72276 for DBI: Wish: fetchrow_hashref_ordered to preserve column ordering

Tue Nov 08 11:05:38 2011 EDAVIS [...] cpan.org - Ticket created

Subject:

Wish: fetchrow_hashref_ordered to preserve column ordering

fetchrow_hashref returns a hash mapping name to value. Because hash keys are unordered this loses the original column ordering from the query. You can reconstruct it using the NAME attribute but it would be handy for DBI to have a method returning a hash with ordered keys, using Tie::IxHash. I imagine it would be called fetchrow_hashref_ordered and would work just as fetchrow_hashref, except it would return a reference to a Tie::IxHash tied hash where the key ordering is the same as that given by NAME. If you like the idea I could write a patch?

Tue Nov 08 12:07:15 2011 HMBRAND [...] cpan.org - Correspondence added

I'd vote against that for two reasons 1. It adds a dependency to DBI 2. It is much faster to use bind_columns (and have the correct order in an array), like $ cat test.csv a,b,c,d,e,f 1,2,3,4,5,6 2,3,4,5,6,7 3,4,5,6,7,8 4,5,6,7,8,9 $ cat test.pl use v5.12; use warnings; use autodie; use DBI; my $dbh = DBI->connect ("dbi:CSV:", undef, undef, { f_ext => ".csv/r", PrintError => 1, RaiseError => 1, }); my $sth = $dbh->prepare ("select * from test"); $sth->execute; my %rec; my @columns = @{$sth->{NAME_lc}}; $sth->bind_columns (\@rec{@columns}); while ($sth->fetch) { say join ", " => map { "$_: $rec{$_}" } @columns; } $ perl test.pl a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 a: 2, b: 3, c: 4, d: 5, e: 6, f: 7 a: 3, b: 4, c: 5, d: 6, e: 7, f: 8 a: 4, b: 5, c: 6, d: 7, e: 8, f: 9 $

Tue Nov 08 12:07:16 2011 The RT System itself - Status changed from 'new' to 'open'

Tue Nov 08 12:27:53 2011 EDAVIS [...] cpan.org - Correspondence added

Hmm, you're right that this would add a dependency. I was mistakenly thinking Tie::IxHash was a core module (surprising it is not, really). It is true that bind_columns is faster. fetchrow_hashref is really just a convenience function for code where raw speed is not important. My suggested function is in the same spirit.

Mon Jan 02 09:33:56 2012 TIMB [...] cpan.org - Correspondence added

I think there's no need to change the DBI for this. It would be easy to add to user code for the very few people who would want it. Thanks for the suggestion.

Mon Jan 02 09:33:58 2012 TIMB [...] cpan.org - Status changed from 'open' to 'rejected'