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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 | |
10 | my $schema = DBICTest->init_schema(); |
11 | |
12 | my $orig_debug = $schema->storage->debug; |
13 | |
14 | use IO::File; |
15 | |
16 | BEGIN { |
17 | eval "use DBD::SQLite"; |
18 | plan $@ |
19 | ? ( skip_all => 'needs DBD::SQLite for testing' ) |
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20 | # : ( tests => 16 ); |
21 | : 'no_plan'; |
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22 | } |
23 | |
24 | # once the following TODO is complete, remove the 2 warning tests immediately |
25 | # after the TODO block |
26 | # (the TODO block itself contains tests ensuring that the warns are removed) |
27 | TODO: { |
28 | local $TODO = 'Prefetch of multiple has_many rels at the same level (currently warn to protect the clueless git)'; |
29 | |
30 | #( 1 -> M + M ) |
31 | my $cd_rs = $schema->resultset('CD')->search ({ 'me.title' => 'Forkful of bees' }); |
32 | my $pr_cd_rs = $cd_rs->search ({}, { |
33 | prefetch => [qw/tracks tags/], |
34 | }); |
35 | |
36 | my $tracks_rs = $cd_rs->first->tracks; |
37 | my $tracks_count = $tracks_rs->count; |
38 | |
39 | my ($pr_tracks_rs, $pr_tracks_count); |
40 | |
41 | my $queries = 0; |
42 | $schema->storage->debugcb(sub { $queries++ }); |
43 | $schema->storage->debug(1); |
44 | |
45 | my $o_mm_warn; |
46 | { |
47 | local $SIG{__WARN__} = sub { $o_mm_warn = shift }; |
48 | $pr_tracks_rs = $pr_cd_rs->first->tracks; |
49 | }; |
50 | $pr_tracks_count = $pr_tracks_rs->count; |
51 | |
52 | ok(! $o_mm_warn, 'no warning on attempt to prefetch several same level has_many\'s (1 -> M + M)'); |
53 | |
54 | is($queries, 1, 'prefetch one->(has_many,has_many) ran exactly 1 query'); |
55 | is($pr_tracks_count, $tracks_count, 'equal count of prefetched relations over several same level has_many\'s (1 -> M + M)'); |
56 | |
57 | for ($pr_tracks_rs, $tracks_rs) { |
58 | $_->result_class ('DBIx::Class::ResultClass::HashRefInflator'); |
59 | } |
60 | |
61 | is_deeply ([$pr_tracks_rs->all], [$tracks_rs->all], 'same structure returned with and without prefetch over several same level has_many\'s (1 -> M + M)'); |
62 | |
63 | #( M -> 1 -> M + M ) |
64 | my $note_rs = $schema->resultset('LinerNotes')->search ({ notes => 'Buy Whiskey!' }); |
65 | my $pr_note_rs = $note_rs->search ({}, { |
66 | prefetch => { |
67 | cd => [qw/tags tracks/] |
68 | }, |
69 | }); |
70 | |
71 | my $tags_rs = $note_rs->first->cd->tags; |
72 | my $tags_count = $tags_rs->count; |
73 | |
74 | my ($pr_tags_rs, $pr_tags_count); |
75 | |
76 | $queries = 0; |
77 | $schema->storage->debugcb(sub { $queries++ }); |
78 | $schema->storage->debug(1); |
79 | |
80 | my $m_o_mm_warn; |
81 | { |
82 | local $SIG{__WARN__} = sub { $m_o_mm_warn = shift }; |
83 | $pr_tags_rs = $pr_note_rs->first->cd->tags; |
84 | }; |
85 | $pr_tags_count = $pr_tags_rs->count; |
86 | |
87 | ok(! $m_o_mm_warn, 'no warning on attempt to prefetch several same level has_many\'s (M -> 1 -> M + M)'); |
88 | |
89 | is($queries, 1, 'prefetch one->(has_many,has_many) ran exactly 1 query'); |
90 | |
91 | is($pr_tags_count, $tags_count, 'equal count of prefetched relations over several same level has_many\'s (M -> 1 -> M + M)'); |
92 | |
93 | for ($pr_tags_rs, $tags_rs) { |
94 | $_->result_class ('DBIx::Class::ResultClass::HashRefInflator'); |
95 | } |
96 | |
97 | is_deeply ([$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)'); |
98 | } |
99 | |
100 | # remove this closure once the TODO above is working |
101 | my $w; |
102 | { |
103 | local $SIG{__WARN__} = sub { $w = shift }; |
104 | |
105 | my $rs = $schema->resultset('CD')->search ({ 'me.title' => 'Forkful of bees' }, { prefetch => [qw/tracks tags/] }); |
106 | for (qw/all count next first/) { |
107 | undef $w; |
108 | my @stuff = $rs->search()->$_; |
109 | like ($w, qr/will currently disrupt both the functionality of .rs->count\(\), and the amount of objects retrievable via .rs->next\(\)/, |
110 | "warning on ->$_ attempt prefetching several same level has_manys (1 -> M + M)"); |
111 | } |
112 | my $rs2 = $schema->resultset('LinerNotes')->search ({ notes => 'Buy Whiskey!' }, { prefetch => { cd => [qw/tags tracks/] } }); |
113 | for (qw/all count next first/) { |
114 | undef $w; |
115 | my @stuff = $rs2->search()->$_; |
116 | like ($w, qr/will currently disrupt both the functionality of .rs->count\(\), and the amount of objects retrievable via .rs->next\(\)/, |
117 | "warning on ->$_ attempt prefetching several same level has_manys (M -> 1 -> M + M)"); |
118 | } |
119 | } |
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120 | |
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121 | |
122 | # Illustration purposes only |
123 | |
124 | { |
125 | package Inf::Dump; |
126 | sub inflate_result { |
127 | return [ @_[2,3] ]; |
128 | } |
129 | } |
130 | |
131 | my $cd = $schema->resultset ('CD')->create ({ |
132 | artist => 1, |
133 | title => 'bad cd', |
134 | year => 1313, |
135 | tags => [ map { { tag => "bad tag $_" } } (1 .. 3) ], |
136 | tracks => [ |
137 | { title => 'bad track 1', cd_single => { |
138 | artist => 1, |
139 | title => 'bad_single', |
140 | year => 1313, |
141 | }}, |
142 | map { { title => "bad track $_" } } (2 .. 3), |
143 | ], |
144 | }); |
145 | |
146 | my $rs = $schema->resultset ('CD')->search ( |
147 | { 'me.cdid' => $cd->id }, |
148 | { prefetch => [ 'tags', { tracks => 'cd_single' } ], result_class => 'Inf::Dump' }, |
149 | ); |
150 | |
151 | use Text::Table; |
152 | my $query = ${$rs->as_query}->[0]; |
153 | my ($cols) = ( $query =~ /SELECT (.+) FROM/); |
154 | my $tb = Text::Table->new (map { $_ => \ ' | ' } (split /,\s*/, $cols) ); |
155 | |
156 | my $c = $rs->cursor; |
157 | while (my @stuff = $c->next) { |
158 | $tb->add (map { defined $_ ? $_ : 'NULL' } (@stuff) ); |
159 | } |
160 | |
161 | $rs->reset; |
162 | note Dumper [ |
163 | "\n$query", |
164 | "\n$tb", |
165 | $rs->next |
166 | ]; |
167 | |
168 | |
169 | |
170 | |
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171 | __END__ |
172 | The solution is to rewrite ResultSet->_collapse_result() and |
173 | ResultSource->resolve_prefetch() to focus on the final results from the collapse |
174 | of the data. Right now, the code doesn't treat the columns from the various |
175 | tables as grouped entities. While there is a concept of hierarchy (so that |
176 | prefetching down relationships does work as expected), there is no idea of what |
177 | the final product should look like and how the various columns in the row would |
178 | play together. So, the actual prefetch datastructure from the search would be |
179 | very useful in working through this problem. We already have access to the PKs |
180 | and sundry for those. So, when collapsing the search result, we know we are |
181 | looking for 1 cd object. We also know we're looking for tracks and tags records |
182 | -independently- of each other. So, we can grab the data for tracks and data for |
183 | tags separately, uniqueing on the PK as appropriate. Then, when we're done with |
184 | the given cd object's datastream, we know we're good. This should work for all |
185 | the various scenarios. |
186 | |
187 | My reccommendation is the row's data is preprocessed first, breaking it up into |
188 | the data for each of the component tables. (This could be done in the single |
189 | table case, too, but probably isn't necessary.) So, starting with something |
190 | like: |
191 | my $row = { |
192 | t1.col1 => 1, |
193 | t1.col2 => 2, |
194 | t2.col1 => 3, |
195 | t2.col2 => 4, |
196 | t3.col1 => 5, |
197 | t3.col2 => 6, |
198 | }; |
199 | it is massaged to look something like: |
200 | my $row_massaged = { |
201 | t1 => { col1 => 1, col2 => 2 }, |
202 | t2 => { col1 => 3, col2 => 4 }, |
203 | t3 => { col1 => 5, col2 => 6 }, |
204 | }; |
205 | At this point, find the stuff that's different is easy enough to do and slotting |
206 | things into the right spot is, likewise, pretty straightforward. |
207 | |
208 | This implies that the collapse attribute can probably disappear or, at the |
209 | least, be turned into a boolean (which is how it's used in every other place). |