X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultClass%2FHashRefInflator.pm;h=dd56130600c405d1f1362bb174f027920f848020;hb=630ba6e5b8cb098e3991e34f6d4ac7e9234639b1;hp=ca6741e13136aac65195cf250cf9d7ce25688556;hpb=137c657c19009ba5ea9c350ed7ee5e69a8a1968b;p=dbsrgits%2FDBIx-Class-Historic.git

diff --git a/lib/DBIx/Class/ResultClass/HashRefInflator.pm b/lib/DBIx/Class/ResultClass/HashRefInflator.pm
index ca6741e..dd56130 100644
--- a/lib/DBIx/Class/ResultClass/HashRefInflator.pm
+++ b/lib/DBIx/Class/ResultClass/HashRefInflator.pm
@@ -1,76 +1,145 @@
 package DBIx::Class::ResultClass::HashRefInflator;
 
+use strict;
+use warnings;
+
 =head1 NAME
 
-DBIx::Class::ResultClass::HashRefInflator
+DBIx::Class::ResultClass::HashRefInflator - Get raw hashrefs from a resultset
 
 =head1 SYNOPSIS
 
- my $rs = $schema->resultset('CD');
+ use DBIx::Class::ResultClass::HashRefInflator;
 
+ my $rs = $schema->resultset('CD');
  $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
+ while (my $hashref = $rs->next) {
+   ...
+ }
+
+  OR as an attribute:
+
+ my $rs = $schema->resultset('CD')->search({}, {
+   result_class => 'DBIx::Class::ResultClass::HashRefInflator',
+ });
+ while (my $hashref = $rs->next) {
+   ...
+ }
 
 =head1 DESCRIPTION
 
-DBIx::Class is not built for speed: it's built for convenience and
-ease of use. But sometimes you just need to get the data, and skip the
-fancy objects. That is what this class provides.
+DBIx::Class is faster than older ORMs like Class::DBI but it still isn't 
+designed primarily for speed. Sometimes you need to quickly retrieve the data
+from a massive resultset, while skipping the creation of fancy row objects.
+Specifying this class as a C<result_class> for a resultset will change C<< $rs->next >>
+to return a plain data hash-ref (or a list of such hash-refs if C<< $rs->all >> is used).
 
-There are two ways of using this class.
+There are two ways of applying this class to a resultset:
 
 =over
 
 =item *
 
 Specify C<< $rs->result_class >> on a specific resultset to affect only that
-resultser (and any chained off of it); or
+resultset (and any chained off of it); or
 
 =item *
 
 Specify C<< __PACKAGE__->result_class >> on your source object to force all
 uses of that result source to be inflated to hash-refs - this approach is not
-recomended
+recommended.
 
 =back
 
+=cut
+
+##############
+# NOTE
+#
+# Generally people use this to gain as much speed as possible. If a new &mk_hash is
+# implemented, it should be benchmarked using the maint/benchmark_hashrefinflator.pl
+# script (in addition to passing all tests of course :). Additional instructions are
+# provided in the script itself.
+#
+
+# This coderef is a simple recursive function
+# Arguments: ($me, $prefetch) from inflate_result() below
+my $mk_hash;
+$mk_hash = sub {
+    if (ref $_[0] eq 'ARRAY') {     # multi relationship
+        return [ map { $mk_hash->(@$_) || () } (@_) ];
+    }
+    else {
+        my $hash = {
+            # the main hash could be an undef if we are processing a skipped-over join
+            $_[0] ? %{$_[0]} : (),
+
+            # the second arg is a hash of arrays for each prefetched relation
+            map
+                { $_ => $mk_hash->( @{$_[1]->{$_}} ) }
+                ( $_[1] ? (keys %{$_[1]}) : () )
+        };
+
+        # if there is at least one defined column consider the resultset real
+        # (and not an emtpy has_many rel containing one empty hashref)
+        # an empty arrayref is an empty multi-sub-prefetch - don't consider
+        # those either
+        for (values %$hash) {
+            if (ref $_ eq 'ARRAY') {
+              return $hash if @$_;
+            }
+            elsif (defined $_) {
+              return $hash;
+            }
+        }
+
+        return undef;
+    }
+};
+
 =head1 METHODS
 
 =head2 inflate_result
 
-Inflates the result and prefetched data into a hash-ref using L<mk_hash>.
+Inflates the result and prefetched data into a hash-ref (invoked by L<DBIx::Class::ResultSet>)
 
 =cut
 
+##################################################################################
+# inflate_result is invoked as:
+# HRI->inflate_result ($resultsource_instance, $main_data_hashref, $prefetch_data_hashref)
 sub inflate_result {
-    my ($self, $source, $me, $prefetch) = @_;
-
-    return mk_hash($me, $prefetch);
+    return $mk_hash->($_[2], $_[3]);
 }
 
-=head2 mk_hash
 
-This does all the work of inflating the (pre)fetched data.
+=head1 CAVEATS
 
-=cut
+=over
 
-sub mk_hash {
-    my ($me, $rest) = @_;
+=item *
 
-    # $me is the hashref of cols/data from the immediate resultsource
-    # $rest is a deep hashref of all the data from the prefetched
-    # related sources.
+This will not work for relationships that have been prefetched. Consider the
+following:
 
-    # to avoid emtpy has_many rels contain one empty hashref
-    return if (not keys %$me);
+ my $artist = $artitsts_rs->search({}, {prefetch => 'cds' })->first;
 
-    return { %$me,
-        map {
-          ( $_ =>
-             ref($rest->{$_}[0]) eq 'ARRAY' ? [ map { mk_hash(@$_) } @{$rest->{$_}} ]
-                                            : mk_hash( @{$rest->{$_}} )
-          )
-        } keys %$rest
-    };
-}
+ my $cds = $artist->cds;
+ $cds->result_class('DBIx::Class::ResultClass::HashRefInflator');
+ my $first = $cds->first; 
+
+C<$first> will B<not> be a hashref, it will be a normal CD row since 
+HashRefInflator only affects resultsets at inflation time, and prefetch causes
+relations to be inflated when the master C<$artist> row is inflated.
+
+=item *
+
+Column value inflation, e.g., using modules like
+L<DBIx::Class::InflateColumn::DateTime>, is not performed.
+The returned hash contains the raw database values.
+
+=back
+
+=cut
 
 1;