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1 | use strict; |
2 | use warnings; |
3 | |
4 | use Test::More; |
5 | use Test::Exception; |
6 | use lib qw(t/lib); |
7 | use DBICTest; |
8 | use Data::Dumper; |
9 | |
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10 | plan tests => 10; |
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11 | |
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12 | my $schema = DBICTest->init_schema(); |
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13 | |
14 | use IO::File; |
15 | |
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16 | # once the following TODO is complete, remove the 2 warning tests immediately |
17 | # after the TODO block |
18 | # (the TODO block itself contains tests ensuring that the warns are removed) |
19 | TODO: { |
20 | local $TODO = 'Prefetch of multiple has_many rels at the same level (currently warn to protect the clueless git)'; |
21 | |
22 | #( 1 -> M + M ) |
23 | my $cd_rs = $schema->resultset('CD')->search ({ 'me.title' => 'Forkful of bees' }); |
24 | my $pr_cd_rs = $cd_rs->search ({}, { |
25 | prefetch => [qw/tracks tags/], |
26 | }); |
27 | |
28 | my $tracks_rs = $cd_rs->first->tracks; |
29 | my $tracks_count = $tracks_rs->count; |
30 | |
31 | my ($pr_tracks_rs, $pr_tracks_count); |
32 | |
33 | my $queries = 0; |
34 | $schema->storage->debugcb(sub { $queries++ }); |
35 | $schema->storage->debug(1); |
36 | |
37 | my $o_mm_warn; |
38 | { |
39 | local $SIG{__WARN__} = sub { $o_mm_warn = shift }; |
40 | $pr_tracks_rs = $pr_cd_rs->first->tracks; |
41 | }; |
42 | $pr_tracks_count = $pr_tracks_rs->count; |
43 | |
44 | ok(! $o_mm_warn, 'no warning on attempt to prefetch several same level has_many\'s (1 -> M + M)'); |
45 | |
46 | is($queries, 1, 'prefetch one->(has_many,has_many) ran exactly 1 query'); |
47 | is($pr_tracks_count, $tracks_count, 'equal count of prefetched relations over several same level has_many\'s (1 -> M + M)'); |
48 | |
49 | for ($pr_tracks_rs, $tracks_rs) { |
50 | $_->result_class ('DBIx::Class::ResultClass::HashRefInflator'); |
51 | } |
52 | |
53 | is_deeply ([$pr_tracks_rs->all], [$tracks_rs->all], 'same structure returned with and without prefetch over several same level has_many\'s (1 -> M + M)'); |
54 | |
55 | #( M -> 1 -> M + M ) |
56 | my $note_rs = $schema->resultset('LinerNotes')->search ({ notes => 'Buy Whiskey!' }); |
57 | my $pr_note_rs = $note_rs->search ({}, { |
58 | prefetch => { |
59 | cd => [qw/tags tracks/] |
60 | }, |
61 | }); |
62 | |
63 | my $tags_rs = $note_rs->first->cd->tags; |
64 | my $tags_count = $tags_rs->count; |
65 | |
66 | my ($pr_tags_rs, $pr_tags_count); |
67 | |
68 | $queries = 0; |
69 | $schema->storage->debugcb(sub { $queries++ }); |
70 | $schema->storage->debug(1); |
71 | |
72 | my $m_o_mm_warn; |
73 | { |
74 | local $SIG{__WARN__} = sub { $m_o_mm_warn = shift }; |
75 | $pr_tags_rs = $pr_note_rs->first->cd->tags; |
76 | }; |
77 | $pr_tags_count = $pr_tags_rs->count; |
78 | |
79 | ok(! $m_o_mm_warn, 'no warning on attempt to prefetch several same level has_many\'s (M -> 1 -> M + M)'); |
80 | |
81 | is($queries, 1, 'prefetch one->(has_many,has_many) ran exactly 1 query'); |
82 | |
83 | is($pr_tags_count, $tags_count, 'equal count of prefetched relations over several same level has_many\'s (M -> 1 -> M + M)'); |
84 | |
85 | for ($pr_tags_rs, $tags_rs) { |
86 | $_->result_class ('DBIx::Class::ResultClass::HashRefInflator'); |
87 | } |
88 | |
89 | is_deeply ([$pr_tags_rs->all], [$tags_rs->all], 'same structure returned with and without prefetch over several same level has_many\'s (M -> 1 -> M + M)'); |
90 | } |
91 | |
92 | # remove this closure once the TODO above is working |
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93 | { |
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94 | my $warn_re = qr/will explode the number of row objects retrievable via/; |
95 | |
96 | my (@w, @dummy); |
97 | local $SIG{__WARN__} = sub { $_[0] =~ $warn_re ? push @w, @_ : warn @_ }; |
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98 | |
99 | my $rs = $schema->resultset('CD')->search ({ 'me.title' => 'Forkful of bees' }, { prefetch => [qw/tracks tags/] }); |
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100 | @w = (); |
101 | @dummy = $rs->first; |
102 | is (@w, 1, 'warning on attempt prefetching several same level has_manys (1 -> M + M)'); |
103 | |
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104 | my $rs2 = $schema->resultset('LinerNotes')->search ({ notes => 'Buy Whiskey!' }, { prefetch => { cd => [qw/tags tracks/] } }); |
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105 | @w = (); |
106 | @dummy = $rs2->first; |
107 | is (@w, 1, 'warning on attempt prefetching several same level has_manys (M -> 1 -> M + M)'); |
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108 | } |
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109 | |
110 | __END__ |
111 | The solution is to rewrite ResultSet->_collapse_result() and |
112 | ResultSource->resolve_prefetch() to focus on the final results from the collapse |
113 | of the data. Right now, the code doesn't treat the columns from the various |
114 | tables as grouped entities. While there is a concept of hierarchy (so that |
115 | prefetching down relationships does work as expected), there is no idea of what |
116 | the final product should look like and how the various columns in the row would |
117 | play together. So, the actual prefetch datastructure from the search would be |
118 | very useful in working through this problem. We already have access to the PKs |
119 | and sundry for those. So, when collapsing the search result, we know we are |
120 | looking for 1 cd object. We also know we're looking for tracks and tags records |
121 | -independently- of each other. So, we can grab the data for tracks and data for |
122 | tags separately, uniqueing on the PK as appropriate. Then, when we're done with |
123 | the given cd object's datastream, we know we're good. This should work for all |
124 | the various scenarios. |
125 | |
126 | My reccommendation is the row's data is preprocessed first, breaking it up into |
127 | the data for each of the component tables. (This could be done in the single |
128 | table case, too, but probably isn't necessary.) So, starting with something |
129 | like: |
130 | my $row = { |
131 | t1.col1 => 1, |
132 | t1.col2 => 2, |
133 | t2.col1 => 3, |
134 | t2.col2 => 4, |
135 | t3.col1 => 5, |
136 | t3.col2 => 6, |
137 | }; |
138 | it is massaged to look something like: |
139 | my $row_massaged = { |
140 | t1 => { col1 => 1, col2 => 2 }, |
141 | t2 => { col1 => 3, col2 => 4 }, |
142 | t3 => { col1 => 5, col2 => 6 }, |
143 | }; |
144 | At this point, find the stuff that's different is easy enough to do and slotting |
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145 | things into the right spot is, likewise, pretty straightforward. Instead of |
146 | storing things in a AoH, store them in a HoH keyed on the PKs of the the table, |
147 | then convert to an AoH after all collapsing is done. |
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148 | |
149 | This implies that the collapse attribute can probably disappear or, at the |
150 | least, be turned into a boolean (which is how it's used in every other place). |