Ditch Carp::Clan for our own thing
[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / ResultClass / HashRefInflator.pm
CommitLineData
b0930c1e 1package DBIx::Class::ResultClass::HashRefInflator;
2
83304545 3use strict;
4use warnings;
5
137c657c 6=head1 NAME
7
b24d86a1 8DBIx::Class::ResultClass::HashRefInflator - Get raw hashrefs from a resultset
137c657c 9
10=head1 SYNOPSIS
11
a5b29361 12 use DBIx::Class::ResultClass::HashRefInflator;
13
137c657c 14 my $rs = $schema->resultset('CD');
137c657c 15 $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
a5b29361 16 while (my $hashref = $rs->next) {
630ba6e5 17 ...
18 }
19
20 OR as an attribute:
21
22 my $rs = $schema->resultset('CD')->search({}, {
23 result_class => 'DBIx::Class::ResultClass::HashRefInflator',
24 });
25 while (my $hashref = $rs->next) {
26 ...
a5b29361 27 }
137c657c 28
29=head1 DESCRIPTION
30
a5b29361 31DBIx::Class is faster than older ORMs like Class::DBI but it still isn't
32designed primarily for speed. Sometimes you need to quickly retrieve the data
33from a massive resultset, while skipping the creation of fancy row objects.
34Specifying this class as a C<result_class> for a resultset will change C<< $rs->next >>
35to return a plain data hash-ref (or a list of such hash-refs if C<< $rs->all >> is used).
137c657c 36
a5b29361 37There are two ways of applying this class to a resultset:
2328814a 38
a5b29361 39=over
137c657c 40
a5b29361 41=item *
137c657c 42
a5b29361 43Specify C<< $rs->result_class >> on a specific resultset to affect only that
44resultset (and any chained off of it); or
137c657c 45
a5b29361 46=item *
137c657c 47
a5b29361 48Specify C<< __PACKAGE__->result_class >> on your source object to force all
49uses of that result source to be inflated to hash-refs - this approach is not
50recommended.
137c657c 51
a5b29361 52=back
137c657c 53
54=cut
b0930c1e 55
2328814a 56##############
57# NOTE
58#
a5b29361 59# Generally people use this to gain as much speed as possible. If a new &mk_hash is
2328814a 60# implemented, it should be benchmarked using the maint/benchmark_hashrefinflator.pl
a5b29361 61# script (in addition to passing all tests of course :). Additional instructions are
2328814a 62# provided in the script itself.
63#
64
a5b29361 65# This coderef is a simple recursive function
66# Arguments: ($me, $prefetch) from inflate_result() below
67my $mk_hash;
68$mk_hash = sub {
2328814a 69 if (ref $_[0] eq 'ARRAY') { # multi relationship
a5b29361 70 return [ map { $mk_hash->(@$_) || () } (@_) ];
2328814a 71 }
72 else {
73 my $hash = {
74 # the main hash could be an undef if we are processing a skipped-over join
75 $_[0] ? %{$_[0]} : (),
76
77 # the second arg is a hash of arrays for each prefetched relation
78 map
a5b29361 79 { $_ => $mk_hash->( @{$_[1]->{$_}} ) }
2328814a 80 ( $_[1] ? (keys %{$_[1]}) : () )
81 };
82
83 # if there is at least one defined column consider the resultset real
84 # (and not an emtpy has_many rel containing one empty hashref)
e8b32a6d 85 # an empty arrayref is an empty multi-sub-prefetch - don't consider
86 # those either
2328814a 87 for (values %$hash) {
e8b32a6d 88 if (ref $_ eq 'ARRAY') {
89 return $hash if @$_;
90 }
91 elsif (defined $_) {
92 return $hash;
93 }
2328814a 94 }
b0930c1e 95
2328814a 96 return undef;
97 }
a5b29361 98};
99
a5b29361 100=head1 METHODS
101
a5b29361 102=head2 inflate_result
103
104Inflates the result and prefetched data into a hash-ref (invoked by L<DBIx::Class::ResultSet>)
105
106=cut
107
e1540ee0 108##################################################################################
109# inflate_result is invoked as:
110# HRI->inflate_result ($resultsource_instance, $main_data_hashref, $prefetch_data_hashref)
a5b29361 111sub inflate_result {
e1540ee0 112 return $mk_hash->($_[2], $_[3]);
2328814a 113}
114
a5b29361 115
116=head1 CAVEATS
117
118=over
119
120=item *
419ff184 121
122This will not work for relationships that have been prefetched. Consider the
123following:
124
125 my $artist = $artitsts_rs->search({}, {prefetch => 'cds' })->first;
126
127 my $cds = $artist->cds;
128 $cds->result_class('DBIx::Class::ResultClass::HashRefInflator');
129 my $first = $cds->first;
130
131C<$first> will B<not> be a hashref, it will be a normal CD row since
132HashRefInflator only affects resultsets at inflation time, and prefetch causes
133relations to be inflated when the master C<$artist> row is inflated.
134
088476d4 135=item *
136
137Column value inflation, e.g., using modules like
138L<DBIx::Class::InflateColumn::DateTime>, is not performed.
139The returned hash contains the raw database values.
140
a5b29361 141=back
142
419ff184 143=cut
144
b0930c1e 1451;