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1 | package #hide from PAUSE |
2 | DBIx::Class::Storage::DBIHacks; |
d28bb90d |
3 | |
4 | # |
5 | # This module contains code that should never have seen the light of day, |
6 | # does not belong in the Storage, or is otherwise unfit for public |
7eb76996 |
7 | # display. The arrival of SQLA2 should immediately oboslete 90% of this |
d28bb90d |
8 | # |
9 | |
10 | use strict; |
11 | use warnings; |
12 | |
13 | use base 'DBIx::Class::Storage'; |
14 | use mro 'c3'; |
15 | |
16 | use Carp::Clan qw/^DBIx::Class/; |
17 | |
18 | # |
19 | # This is the code producing joined subqueries like: |
20 | # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ... |
21 | # |
22 | sub _adjust_select_args_for_complex_prefetch { |
23 | my ($self, $from, $select, $where, $attrs) = @_; |
24 | |
25 | $self->throw_exception ('Nothing to prefetch... how did we get here?!') |
26 | if not @{$attrs->{_prefetch_select}}; |
27 | |
28 | $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute') |
29 | if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY'); |
30 | |
31 | |
32 | # generate inner/outer attribute lists, remove stuff that doesn't apply |
33 | my $outer_attrs = { %$attrs }; |
34 | delete $outer_attrs->{$_} for qw/where bind rows offset group_by having/; |
35 | |
36 | my $inner_attrs = { %$attrs }; |
37 | delete $inner_attrs->{$_} for qw/for collapse _prefetch_select _collapse_order_by select as/; |
38 | |
39 | |
40 | # bring over all non-collapse-induced order_by into the inner query (if any) |
41 | # the outer one will have to keep them all |
42 | delete $inner_attrs->{order_by}; |
43 | if (my $ord_cnt = @{$outer_attrs->{order_by}} - @{$outer_attrs->{_collapse_order_by}} ) { |
44 | $inner_attrs->{order_by} = [ |
45 | @{$outer_attrs->{order_by}}[ 0 .. $ord_cnt - 1] |
46 | ]; |
47 | } |
48 | |
49 | |
50 | # generate the inner/outer select lists |
51 | # for inside we consider only stuff *not* brought in by the prefetch |
52 | # on the outside we substitute any function for its alias |
53 | my $outer_select = [ @$select ]; |
54 | my $inner_select = []; |
55 | for my $i (0 .. ( @$outer_select - @{$outer_attrs->{_prefetch_select}} - 1) ) { |
56 | my $sel = $outer_select->[$i]; |
57 | |
58 | if (ref $sel eq 'HASH' ) { |
59 | $sel->{-as} ||= $attrs->{as}[$i]; |
60 | $outer_select->[$i] = join ('.', $attrs->{alias}, ($sel->{-as} || "inner_column_$i") ); |
61 | } |
62 | |
63 | push @$inner_select, $sel; |
64 | } |
65 | |
66 | # normalize a copy of $from, so it will be easier to work with further |
67 | # down (i.e. promote the initial hashref to an AoH) |
68 | $from = [ @$from ]; |
69 | $from->[0] = [ $from->[0] ]; |
d28bb90d |
70 | |
07f31d19 |
71 | my ( $restrict_aliases, $select_aliases, $prefetch_aliases ) = |
72 | $self->_choose_aliases_to_include( $from, $where, $inner_select, $inner_attrs, $outer_select, |
73 | $outer_attrs, ); |
d28bb90d |
74 | |
75 | |
d28bb90d |
76 | # construct the inner $from for the subquery |
77 | my %inner_joins = (map { %{$_ || {}} } ($restrict_aliases, $select_aliases) ); |
78 | my @inner_from; |
79 | for my $j (@$from) { |
80 | push @inner_from, $j if $inner_joins{$j->[0]{-alias}}; |
81 | } |
82 | |
83 | # if a multi-type join was needed in the subquery ("multi" is indicated by |
84 | # presence in {collapse}) - add a group_by to simulate the collapse in the subq |
85 | unless ($inner_attrs->{group_by}) { |
86 | for my $alias (keys %inner_joins) { |
87 | |
88 | # the dot comes from some weirdness in collapse |
89 | # remove after the rewrite |
90 | if ($attrs->{collapse}{".$alias"}) { |
91 | $inner_attrs->{group_by} ||= $inner_select; |
92 | last; |
93 | } |
94 | } |
95 | } |
96 | |
97 | # demote the inner_from head |
98 | $inner_from[0] = $inner_from[0][0]; |
99 | |
100 | # generate the subquery |
101 | my $subq = $self->_select_args_to_query ( |
102 | \@inner_from, |
103 | $inner_select, |
104 | $where, |
105 | $inner_attrs, |
106 | ); |
107 | |
108 | my $subq_joinspec = { |
109 | -alias => $attrs->{alias}, |
110 | -source_handle => $inner_from[0]{-source_handle}, |
111 | $attrs->{alias} => $subq, |
112 | }; |
113 | |
114 | # Generate the outer from - this is relatively easy (really just replace |
115 | # the join slot with the subquery), with a major caveat - we can not |
116 | # join anything that is non-selecting (not part of the prefetch), but at |
117 | # the same time is a multi-type relationship, as it will explode the result. |
118 | # |
119 | # There are two possibilities here |
120 | # - either the join is non-restricting, in which case we simply throw it away |
121 | # - it is part of the restrictions, in which case we need to collapse the outer |
122 | # result by tackling yet another group_by to the outside of the query |
123 | |
124 | # so first generate the outer_from, up to the substitution point |
125 | my @outer_from; |
126 | while (my $j = shift @$from) { |
127 | if ($j->[0]{-alias} eq $attrs->{alias}) { # time to swap |
128 | push @outer_from, [ |
129 | $subq_joinspec, |
130 | @{$j}[1 .. $#$j], |
131 | ]; |
132 | last; # we'll take care of what's left in $from below |
133 | } |
134 | else { |
135 | push @outer_from, $j; |
136 | } |
137 | } |
138 | |
139 | # see what's left - throw away if not selecting/restricting |
140 | # also throw in a group_by if restricting to guard against |
141 | # cross-join explosions |
142 | # |
143 | while (my $j = shift @$from) { |
144 | my $alias = $j->[0]{-alias}; |
145 | |
146 | if ($select_aliases->{$alias} || $prefetch_aliases->{$alias}) { |
147 | push @outer_from, $j; |
148 | } |
149 | elsif ($restrict_aliases->{$alias}) { |
150 | push @outer_from, $j; |
151 | |
152 | # FIXME - this should be obviated by SQLA2, as I'll be able to |
153 | # have restrict_inner and restrict_outer... or something to that |
154 | # effect... I think... |
155 | |
156 | # FIXME2 - I can't find a clean way to determine if a particular join |
157 | # is a multi - instead I am just treating everything as a potential |
158 | # explosive join (ribasushi) |
159 | # |
160 | # if (my $handle = $j->[0]{-source_handle}) { |
161 | # my $rsrc = $handle->resolve; |
162 | # ... need to bail out of the following if this is not a multi, |
163 | # as it will be much easier on the db ... |
164 | |
165 | $outer_attrs->{group_by} ||= $outer_select; |
166 | # } |
167 | } |
168 | } |
169 | |
170 | # demote the outer_from head |
171 | $outer_from[0] = $outer_from[0][0]; |
172 | |
173 | # This is totally horrific - the $where ends up in both the inner and outer query |
174 | # Unfortunately not much can be done until SQLA2 introspection arrives, and even |
175 | # then if where conditions apply to the *right* side of the prefetch, you may have |
176 | # to both filter the inner select (e.g. to apply a limit) and then have to re-filter |
177 | # the outer select to exclude joins you didin't want in the first place |
178 | # |
179 | # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;) |
180 | return (\@outer_from, $outer_select, $where, $outer_attrs); |
181 | } |
182 | |
07f31d19 |
183 | sub _choose_aliases_to_include { |
184 | my ( $self, $from, $where, $inner_select, $inner_attrs, $outer_select, |
185 | $outer_attrs ) = @_; |
186 | |
187 | my %original_join_info = map { $_->[0]{-alias} => $_->[0] } (@$from); |
188 | # decide which parts of the join will remain in either part of |
189 | # the outer/inner query |
190 | |
191 | # First we compose a list of which aliases are used in restrictions |
192 | # (i.e. conditions/order/grouping/etc). Since we do not have |
193 | # introspectable SQLA, we fall back to ugly scanning of raw SQL for |
194 | # WHERE, and for pieces of ORDER BY in order to determine which aliases |
195 | # need to appear in the resulting sql. |
196 | # It may not be very efficient, but it's a reasonable stop-gap |
197 | # Also unqualified column names will not be considered, but more often |
198 | # than not this is actually ok |
199 | # |
200 | # In the same loop we enumerate part of the selection aliases, as |
201 | # it requires the same sqla hack for the time being |
202 | my ($restrict_aliases, $select_aliases, $prefetch_aliases); |
203 | { |
204 | # produce stuff unquoted, so it can be scanned |
205 | my $sql_maker = $self->sql_maker; |
206 | local $sql_maker->{quote_char}; |
207 | my $sep = $self->_sql_maker_opts->{name_sep} || '.'; |
208 | $sep = "\Q$sep\E"; |
209 | |
210 | my $non_prefetch_select_sql = $sql_maker->_recurse_fields ($inner_select); |
211 | my $prefetch_select_sql = $sql_maker->_recurse_fields ($outer_attrs->{_prefetch_select}); |
212 | my $where_sql = $sql_maker->where ($where); |
213 | my $group_by_sql = $sql_maker->_order_by({ |
214 | map { $_ => $inner_attrs->{$_} } qw/group_by having/ |
215 | }); |
216 | my @non_prefetch_order_by_chunks = (map |
217 | { ref $_ ? $_->[0] : $_ } |
218 | $sql_maker->_order_by_chunks ($inner_attrs->{order_by}) |
219 | ); |
220 | |
221 | |
222 | for my $alias (keys %original_join_info) { |
223 | my $seen_re = qr/\b $alias $sep/x; |
224 | |
225 | for my $piece ($where_sql, $group_by_sql, @non_prefetch_order_by_chunks ) { |
226 | if ($piece =~ $seen_re) { |
227 | $restrict_aliases->{$alias} = 1; |
228 | } |
229 | } |
230 | |
231 | if ($non_prefetch_select_sql =~ $seen_re) { |
232 | $select_aliases->{$alias} = 1; |
233 | } |
234 | |
235 | if ($prefetch_select_sql =~ $seen_re) { |
236 | $prefetch_aliases->{$alias} = 1; |
237 | } |
238 | |
239 | } |
240 | } |
241 | |
242 | # Add any non-left joins to the restriction list (such joins are indeed restrictions) |
243 | for my $j (values %original_join_info) { |
244 | my $alias = $j->{-alias} or next; |
245 | $restrict_aliases->{$alias} = 1 if ( |
246 | (not $j->{-join_type}) |
247 | or |
248 | ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi) |
249 | ); |
250 | } |
251 | |
252 | # mark all join parents as mentioned |
253 | # (e.g. join => { cds => 'tracks' } - tracks will need to bring cds too ) |
254 | for my $collection ($restrict_aliases, $select_aliases) { |
255 | for my $alias (keys %$collection) { |
256 | $collection->{$_} = 1 |
257 | for (@{ $original_join_info{$alias}{-join_path} || [] }); |
258 | } |
259 | } |
260 | return ( $restrict_aliases, $select_aliases, $prefetch_aliases ); |
261 | } |
262 | |
d28bb90d |
263 | sub _resolve_ident_sources { |
264 | my ($self, $ident) = @_; |
265 | |
266 | my $alias2source = {}; |
267 | my $rs_alias; |
268 | |
269 | # the reason this is so contrived is that $ident may be a {from} |
270 | # structure, specifying multiple tables to join |
271 | if ( Scalar::Util::blessed($ident) && $ident->isa("DBIx::Class::ResultSource") ) { |
272 | # this is compat mode for insert/update/delete which do not deal with aliases |
273 | $alias2source->{me} = $ident; |
274 | $rs_alias = 'me'; |
275 | } |
276 | elsif (ref $ident eq 'ARRAY') { |
277 | |
278 | for (@$ident) { |
279 | my $tabinfo; |
280 | if (ref $_ eq 'HASH') { |
281 | $tabinfo = $_; |
282 | $rs_alias = $tabinfo->{-alias}; |
283 | } |
284 | if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') { |
285 | $tabinfo = $_->[0]; |
286 | } |
287 | |
288 | $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-source_handle}->resolve |
289 | if ($tabinfo->{-source_handle}); |
290 | } |
291 | } |
292 | |
293 | return ($alias2source, $rs_alias); |
294 | } |
295 | |
296 | # Takes $ident, \@column_names |
297 | # |
298 | # returns { $column_name => \%column_info, ... } |
299 | # also note: this adds -result_source => $rsrc to the column info |
300 | # |
09e14fdc |
301 | # If no columns_names are supplied returns info about *all* columns |
302 | # for all sources |
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303 | sub _resolve_column_info { |
304 | my ($self, $ident, $colnames) = @_; |
305 | my ($alias2src, $root_alias) = $self->_resolve_ident_sources($ident); |
306 | |
307 | my $sep = $self->_sql_maker_opts->{name_sep} || '.'; |
09e14fdc |
308 | my $qsep = quotemeta $sep; |
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309 | |
09e14fdc |
310 | my (%return, %seen_cols, @auto_colnames); |
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311 | |
312 | # compile a global list of column names, to be able to properly |
313 | # disambiguate unqualified column names (if at all possible) |
314 | for my $alias (keys %$alias2src) { |
315 | my $rsrc = $alias2src->{$alias}; |
316 | for my $colname ($rsrc->columns) { |
317 | push @{$seen_cols{$colname}}, $alias; |
09e14fdc |
318 | push @auto_colnames, "$alias$sep$colname" unless $colnames; |
d28bb90d |
319 | } |
320 | } |
321 | |
09e14fdc |
322 | $colnames ||= [ |
323 | @auto_colnames, |
324 | grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols), |
325 | ]; |
326 | |
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327 | COLUMN: |
328 | foreach my $col (@$colnames) { |
09e14fdc |
329 | my ($alias, $colname) = $col =~ m/^ (?: ([^$qsep]+) $qsep)? (.+) $/x; |
d28bb90d |
330 | |
331 | unless ($alias) { |
332 | # see if the column was seen exactly once (so we know which rsrc it came from) |
333 | if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1) { |
334 | $alias = $seen_cols{$colname}[0]; |
335 | } |
336 | else { |
337 | next COLUMN; |
338 | } |
339 | } |
340 | |
341 | my $rsrc = $alias2src->{$alias}; |
342 | $return{$col} = $rsrc && { |
343 | %{$rsrc->column_info($colname)}, |
344 | -result_source => $rsrc, |
345 | -source_alias => $alias, |
346 | }; |
347 | } |
348 | |
349 | return \%return; |
350 | } |
351 | |
289ac713 |
352 | # The DBIC relationship chaining implementation is pretty simple - every |
353 | # new related_relationship is pushed onto the {from} stack, and the {select} |
354 | # window simply slides further in. This means that when we count somewhere |
355 | # in the middle, we got to make sure that everything in the join chain is an |
356 | # actual inner join, otherwise the count will come back with unpredictable |
357 | # results (a resultset may be generated with _some_ rows regardless of if |
358 | # the relation which the $rs currently selects has rows or not). E.g. |
359 | # $artist_rs->cds->count - normally generates: |
360 | # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid |
361 | # which actually returns the number of artists * (number of cds || 1) |
362 | # |
363 | # So what we do here is crawl {from}, determine if the current alias is at |
364 | # the top of the stack, and if not - make sure the chain is inner-joined down |
365 | # to the root. |
366 | # |
367 | sub _straight_join_to_node { |
368 | my ($self, $from, $alias) = @_; |
369 | |
370 | # subqueries and other oddness are naturally not supported |
371 | return $from if ( |
372 | ref $from ne 'ARRAY' |
373 | || |
374 | @$from <= 1 |
375 | || |
376 | ref $from->[0] ne 'HASH' |
377 | || |
378 | ! $from->[0]{-alias} |
379 | || |
7eb76996 |
380 | $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do |
289ac713 |
381 | ); |
382 | |
383 | # find the current $alias in the $from structure |
384 | my $switch_branch; |
385 | JOINSCAN: |
386 | for my $j (@{$from}[1 .. $#$from]) { |
387 | if ($j->[0]{-alias} eq $alias) { |
388 | $switch_branch = $j->[0]{-join_path}; |
389 | last JOINSCAN; |
390 | } |
391 | } |
392 | |
7eb76996 |
393 | # something else went quite wrong |
289ac713 |
394 | return $from unless $switch_branch; |
395 | |
396 | # So it looks like we will have to switch some stuff around. |
397 | # local() is useless here as we will be leaving the scope |
398 | # anyway, and deep cloning is just too fucking expensive |
7eb76996 |
399 | # So replace the first hashref in the node arrayref manually |
289ac713 |
400 | my @new_from = ($from->[0]); |
401 | my $sw_idx = { map { $_ => 1 } @$switch_branch }; |
402 | |
403 | for my $j (@{$from}[1 .. $#$from]) { |
404 | my $jalias = $j->[0]{-alias}; |
405 | |
406 | if ($sw_idx->{$jalias}) { |
407 | my %attrs = %{$j->[0]}; |
408 | delete $attrs{-join_type}; |
409 | push @new_from, [ |
410 | \%attrs, |
411 | @{$j}[ 1 .. $#$j ], |
412 | ]; |
413 | } |
414 | else { |
415 | push @new_from, $j; |
416 | } |
417 | } |
418 | |
419 | return \@new_from; |
420 | } |
421 | |
bac6c4fb |
422 | # Most databases do not allow aliasing of tables in UPDATE/DELETE. Thus |
423 | # a condition containing 'me' or other table prefixes will not work |
424 | # at all. What this code tries to do (badly) is introspect the condition |
425 | # and remove all column qualifiers. If it bails out early (returns undef) |
426 | # the calling code should try another approach (e.g. a subquery) |
427 | sub _strip_cond_qualifiers { |
428 | my ($self, $where) = @_; |
429 | |
430 | my $cond = {}; |
431 | |
432 | # No-op. No condition, we're updating/deleting everything |
433 | return $cond unless $where; |
434 | |
435 | if (ref $where eq 'ARRAY') { |
436 | $cond = [ |
437 | map { |
438 | my %hash; |
439 | foreach my $key (keys %{$_}) { |
440 | $key =~ /([^.]+)$/; |
441 | $hash{$1} = $_->{$key}; |
442 | } |
443 | \%hash; |
444 | } @$where |
445 | ]; |
446 | } |
447 | elsif (ref $where eq 'HASH') { |
448 | if ( (keys %$where) == 1 && ( (keys %{$where})[0] eq '-and' )) { |
449 | $cond->{-and} = []; |
450 | my @cond = @{$where->{-and}}; |
451 | for (my $i = 0; $i < @cond; $i++) { |
452 | my $entry = $cond[$i]; |
453 | my $hash; |
454 | if (ref $entry eq 'HASH') { |
455 | $hash = $self->_strip_cond_qualifiers($entry); |
456 | } |
457 | else { |
458 | $entry =~ /([^.]+)$/; |
459 | $hash->{$1} = $cond[++$i]; |
460 | } |
461 | push @{$cond->{-and}}, $hash; |
462 | } |
463 | } |
464 | else { |
465 | foreach my $key (keys %$where) { |
466 | $key =~ /([^.]+)$/; |
467 | $cond->{$1} = $where->{$key}; |
468 | } |
469 | } |
470 | } |
471 | else { |
472 | return undef; |
473 | } |
474 | |
475 | return $cond; |
476 | } |
477 | |
478 | |
d28bb90d |
479 | 1; |