Commit | Line | Data |
2bb7b40b |
1 | package DBIx::Class::ResultSetColumn; |
1a58752c |
2 | |
2bb7b40b |
3 | use strict; |
4 | use warnings; |
1a58752c |
5 | |
2bb7b40b |
6 | use base 'DBIx::Class'; |
1a58752c |
7 | |
722c0140 |
8 | use Carp::Clan qw/^DBIx::Class/; |
1a58752c |
9 | use DBIx::Class::Exception; |
66521001 |
10 | use List::Util; |
2bb7b40b |
11 | |
12 | =head1 NAME |
13 | |
14 | DBIx::Class::ResultSetColumn - helpful methods for messing |
15 | with a single column of the resultset |
16 | |
17 | =head1 SYNOPSIS |
18 | |
19 | $rs = $schema->resultset('CD')->search({ artist => 'Tool' }); |
20 | $rs_column = $rs->get_column('year'); |
21 | $max_year = $rs_column->max; #returns latest year |
22 | |
23 | =head1 DESCRIPTION |
24 | |
eb98561c |
25 | A convenience class used to perform operations on a specific column of |
26 | a resultset. |
2bb7b40b |
27 | |
28 | =cut |
29 | |
30 | =head1 METHODS |
31 | |
32 | =head2 new |
33 | |
34 | my $obj = DBIx::Class::ResultSetColumn->new($rs, $column); |
35 | |
eb98561c |
36 | Creates a new resultset column object from the resultset and column |
37 | passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>. |
2bb7b40b |
38 | |
39 | =cut |
40 | |
41 | sub new { |
42 | my ($class, $rs, $column) = @_; |
43 | $class = ref $class if ref $class; |
7ae9706c |
44 | |
66e33361 |
45 | $rs->throw_exception('column must be supplied') unless $column; |
7ae9706c |
46 | |
d8dbe471 |
47 | my $orig_attrs = $rs->_resolved_attrs; |
9b8930f4 |
48 | my $alias = $rs->current_source_alias; |
472d7df3 |
49 | |
50 | # If $column can be found in the 'as' list of the parent resultset, use the |
51 | # corresponding element of its 'select' list (to keep any custom column |
52 | # definition set up with 'select' or '+select' attrs), otherwise use $column |
53 | # (to create a new column definition on-the-fly). |
54 | my $as_list = $orig_attrs->{as} || []; |
55 | my $select_list = $orig_attrs->{select} || []; |
56 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
57 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
58 | |
59 | my $new_parent_rs; |
60 | # analyze the order_by, and see if it is done over a function/nonexistentcolumn |
61 | # if this is the case we will need to wrap a subquery since the result of RSC |
62 | # *must* be a single column select |
9b8930f4 |
63 | my %collist = map |
64 | { $_ => 1, ($_ =~ /\./) ? () : ( "$alias.$_" => 1 ) } |
65 | ($rs->result_source->columns, $column) |
66 | ; |
472d7df3 |
67 | if ( |
68 | scalar grep |
69 | { ! $collist{$_} } |
70 | ( $rs->result_source->schema->storage->_parse_order_by ($orig_attrs->{order_by} ) ) |
71 | ) { |
5716e003 |
72 | # nuke the prefetch before collapsing to sql |
73 | my $subq_rs = $rs->search; |
74 | $subq_rs->{attrs}{join} = $subq_rs->_merge_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} ); |
9b8930f4 |
75 | $new_parent_rs = $subq_rs->as_subselect_rs; |
472d7df3 |
76 | } |
77 | |
78 | $new_parent_rs ||= $rs->search_rs; |
66e33361 |
79 | my $new_attrs = $new_parent_rs->{attrs} ||= {}; |
80 | |
7ae9706c |
81 | # prefetch causes additional columns to be fetched, but we can not just make a new |
82 | # rs via the _resolved_attrs trick - we need to retain the separation between |
bed3a173 |
83 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
84 | # prefetch would otherwise generate. |
5716e003 |
85 | $new_attrs->{join} = $rs->_merge_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} ); |
b6e85b48 |
86 | |
d8dbe471 |
87 | # {collapse} would mean a has_many join was injected, which in turn means |
722c0140 |
88 | # we need to group *IF WE CAN* (only if the column in question is unique) |
9b8930f4 |
89 | if (!$orig_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) { |
d8dbe471 |
90 | |
91 | # scan for a constraint that would contain our column only - that'd be proof |
92 | # enough it is unique |
93 | my $constraints = { $rs->result_source->unique_constraints }; |
94 | for my $constraint_columns ( values %$constraints ) { |
95 | |
96 | next unless @$constraint_columns == 1; |
97 | |
98 | my $col = $constraint_columns->[0]; |
99 | my $fqcol = join ('.', $new_attrs->{alias}, $col); |
100 | |
101 | if ($col eq $select or $fqcol eq $select) { |
102 | $new_attrs->{group_by} = [ $select ]; |
722c0140 |
103 | delete $new_attrs->{distinct}; # it is ignored when group_by is present |
d8dbe471 |
104 | last; |
105 | } |
106 | } |
722c0140 |
107 | |
108 | if (!$new_attrs->{group_by}) { |
109 | carp ( |
110 | "Attempting to retrieve non-unique column '$column' on a resultset containing " |
111 | . 'one-to-many joins will return duplicate results.' |
112 | ); |
113 | } |
d8dbe471 |
114 | } |
115 | |
b6e85b48 |
116 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
2bb7b40b |
117 | return $new; |
118 | } |
119 | |
6dfbe2f8 |
120 | =head2 as_query |
658fa250 |
121 | |
122 | =over 4 |
123 | |
428a645e |
124 | =item Arguments: none |
658fa250 |
125 | |
4dc99a01 |
126 | =item Return Value: \[ $sql, @bind ] |
658fa250 |
127 | |
128 | =back |
129 | |
130 | Returns the SQL query and bind vars associated with the invocant. |
131 | |
03834f77 |
132 | This is generally used as the RHS for a subquery. |
c7a9d102 |
133 | |
134 | =cut |
135 | |
0f6fc705 |
136 | sub as_query { return shift->_resultset->as_query(@_) } |
c7a9d102 |
137 | |
2bb7b40b |
138 | =head2 next |
139 | |
140 | =over 4 |
141 | |
142 | =item Arguments: none |
143 | |
144 | =item Return Value: $value |
145 | |
146 | =back |
147 | |
eb98561c |
148 | Returns the next value of the column in the resultset (or C<undef> if |
149 | there is none). |
2bb7b40b |
150 | |
eb98561c |
151 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
152 | one value. |
2bb7b40b |
153 | |
154 | =cut |
155 | |
156 | sub next { |
157 | my $self = shift; |
b7c79955 |
158 | |
159 | # using cursor so we don't inflate anything |
66521001 |
160 | my ($row) = $self->_resultset->cursor->next; |
b7c79955 |
161 | |
2bb7b40b |
162 | return $row; |
163 | } |
164 | |
165 | =head2 all |
166 | |
167 | =over 4 |
168 | |
169 | =item Arguments: none |
170 | |
171 | =item Return Value: @values |
172 | |
173 | =back |
174 | |
eb98561c |
175 | Returns all values of the column in the resultset (or C<undef> if |
176 | there are none). |
2bb7b40b |
177 | |
eb98561c |
178 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
179 | than row objects. |
2bb7b40b |
180 | |
181 | =cut |
182 | |
183 | sub all { |
184 | my $self = shift; |
b7c79955 |
185 | |
186 | # using cursor so we don't inflate anything |
66521001 |
187 | return map { $_->[0] } $self->_resultset->cursor->all; |
188 | } |
189 | |
190 | =head2 reset |
191 | |
192 | =over 4 |
193 | |
194 | =item Arguments: none |
195 | |
196 | =item Return Value: $self |
197 | |
198 | =back |
199 | |
200 | Resets the underlying resultset's cursor, so you can iterate through the |
201 | elements of the column again. |
202 | |
203 | Much like L<DBIx::Class::ResultSet/reset>. |
204 | |
205 | =cut |
206 | |
207 | sub reset { |
208 | my $self = shift; |
209 | $self->_resultset->cursor->reset; |
b7c79955 |
210 | return $self; |
66521001 |
211 | } |
212 | |
213 | =head2 first |
214 | |
215 | =over 4 |
216 | |
217 | =item Arguments: none |
218 | |
219 | =item Return Value: $value |
220 | |
221 | =back |
222 | |
223 | Resets the underlying resultset and returns the next value of the column in the |
224 | resultset (or C<undef> if there is none). |
225 | |
226 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
227 | |
228 | =cut |
229 | |
230 | sub first { |
231 | my $self = shift; |
b7c79955 |
232 | |
233 | # using cursor so we don't inflate anything |
234 | $self->_resultset->cursor->reset; |
01dc6781 |
235 | my ($row) = $self->_resultset->cursor->next; |
b7c79955 |
236 | |
66521001 |
237 | return $row; |
2bb7b40b |
238 | } |
239 | |
4e55c3ae |
240 | =head2 single |
241 | |
242 | =over 4 |
243 | |
244 | =item Arguments: none |
245 | |
246 | =item Return Value: $value |
247 | |
248 | =back |
249 | |
250 | Much like L<DBIx::Class::ResultSet/single> fetches one and only one column |
251 | value using the cursor directly. If additional rows are present a warning |
252 | is issued before discarding the cursor. |
253 | |
254 | =cut |
255 | |
256 | sub single { |
257 | my $self = shift; |
258 | |
259 | my $attrs = $self->_resultset->_resolved_attrs; |
260 | my ($row) = $self->_resultset->result_source->storage->select_single( |
261 | $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs |
262 | ); |
263 | |
264 | return $row; |
265 | } |
266 | |
2bb7b40b |
267 | =head2 min |
268 | |
269 | =over 4 |
270 | |
271 | =item Arguments: none |
272 | |
273 | =item Return Value: $lowest_value |
274 | |
275 | =back |
276 | |
eb98561c |
277 | my $first_year = $year_col->min(); |
278 | |
279 | Wrapper for ->func. Returns the lowest value of the column in the |
280 | resultset (or C<undef> if there are none). |
2bb7b40b |
281 | |
282 | =cut |
283 | |
284 | sub min { |
6b051e14 |
285 | return shift->func('MIN'); |
2bb7b40b |
286 | } |
287 | |
4fa7bc22 |
288 | =head2 min_rs |
289 | |
290 | =over 4 |
291 | |
292 | =item Arguments: none |
293 | |
294 | =item Return Value: $resultset |
295 | |
296 | =back |
297 | |
298 | my $rs = $year_col->min_rs(); |
299 | |
300 | Wrapper for ->func_rs for function MIN(). |
301 | |
302 | =cut |
303 | |
304 | sub min_rs { return shift->func_rs('MIN') } |
305 | |
2bb7b40b |
306 | =head2 max |
307 | |
308 | =over 4 |
309 | |
310 | =item Arguments: none |
311 | |
312 | =item Return Value: $highest_value |
313 | |
314 | =back |
315 | |
eb98561c |
316 | my $last_year = $year_col->max(); |
317 | |
318 | Wrapper for ->func. Returns the highest value of the column in the |
319 | resultset (or C<undef> if there are none). |
2bb7b40b |
320 | |
321 | =cut |
322 | |
323 | sub max { |
6b051e14 |
324 | return shift->func('MAX'); |
2bb7b40b |
325 | } |
326 | |
4fa7bc22 |
327 | =head2 max_rs |
328 | |
329 | =over 4 |
330 | |
331 | =item Arguments: none |
332 | |
333 | =item Return Value: $resultset |
334 | |
335 | =back |
336 | |
337 | my $rs = $year_col->max_rs(); |
338 | |
339 | Wrapper for ->func_rs for function MAX(). |
340 | |
341 | =cut |
342 | |
343 | sub max_rs { return shift->func_rs('MAX') } |
344 | |
2bb7b40b |
345 | =head2 sum |
346 | |
347 | =over 4 |
348 | |
349 | =item Arguments: none |
350 | |
351 | =item Return Value: $sum_of_values |
352 | |
353 | =back |
354 | |
eb98561c |
355 | my $total = $prices_col->sum(); |
356 | |
357 | Wrapper for ->func. Returns the sum of all the values in the column of |
358 | the resultset. Use on varchar-like columns at your own risk. |
2bb7b40b |
359 | |
360 | =cut |
361 | |
362 | sub sum { |
6b051e14 |
363 | return shift->func('SUM'); |
2bb7b40b |
364 | } |
365 | |
4fa7bc22 |
366 | =head2 sum_rs |
367 | |
368 | =over 4 |
369 | |
370 | =item Arguments: none |
371 | |
372 | =item Return Value: $resultset |
373 | |
374 | =back |
375 | |
376 | my $rs = $year_col->sum_rs(); |
377 | |
378 | Wrapper for ->func_rs for function SUM(). |
379 | |
380 | =cut |
381 | |
382 | sub sum_rs { return shift->func_rs('SUM') } |
383 | |
2bb7b40b |
384 | =head2 func |
385 | |
386 | =over 4 |
387 | |
388 | =item Arguments: $function |
389 | |
390 | =item Return Value: $function_return_value |
391 | |
392 | =back |
393 | |
e8419341 |
394 | $rs = $schema->resultset("CD")->search({}); |
395 | $length = $rs->get_column('title')->func('LENGTH'); |
2bb7b40b |
396 | |
eb98561c |
397 | Runs a query using the function on the column and returns the |
398 | value. Produces the following SQL: |
399 | |
400 | SELECT LENGTH( title ) FROM cd me |
2bb7b40b |
401 | |
402 | =cut |
403 | |
404 | sub func { |
6b051e14 |
405 | my ($self,$function) = @_; |
4fa7bc22 |
406 | my $cursor = $self->func_rs($function)->cursor; |
d4daee7b |
407 | |
5d62876f |
408 | if( wantarray ) { |
409 | return map { $_->[ 0 ] } $cursor->all; |
410 | } |
411 | |
412 | return ( $cursor->next )[ 0 ]; |
2bb7b40b |
413 | } |
414 | |
4fa7bc22 |
415 | =head2 func_rs |
416 | |
417 | =over 4 |
418 | |
419 | =item Arguments: $function |
420 | |
421 | =item Return Value: $resultset |
422 | |
423 | =back |
424 | |
425 | Creates the resultset that C<func()> uses to run its query. |
426 | |
427 | =cut |
428 | |
429 | sub func_rs { |
430 | my ($self,$function) = @_; |
431 | return $self->{_parent_resultset}->search( |
432 | undef, { |
433 | select => {$function => $self->{_select}}, |
434 | as => [$self->{_as}], |
435 | }, |
436 | ); |
437 | } |
438 | |
5d1fc7dc |
439 | =head2 throw_exception |
440 | |
441 | See L<DBIx::Class::Schema/throw_exception> for details. |
d4daee7b |
442 | |
5d1fc7dc |
443 | =cut |
d4daee7b |
444 | |
5d1fc7dc |
445 | sub throw_exception { |
446 | my $self=shift; |
1a58752c |
447 | |
5d1fc7dc |
448 | if (ref $self && $self->{_parent_resultset}) { |
1a58752c |
449 | $self->{_parent_resultset}->throw_exception(@_); |
450 | } |
451 | else { |
452 | DBIx::Class::Exception->throw(@_); |
5d1fc7dc |
453 | } |
454 | } |
455 | |
b6e85b48 |
456 | # _resultset |
457 | # |
458 | # Arguments: none |
459 | # |
460 | # Return Value: $resultset |
461 | # |
462 | # $year_col->_resultset->next |
463 | # |
464 | # Returns the underlying resultset. Creates it from the parent resultset if |
465 | # necessary. |
b7c79955 |
466 | # |
66521001 |
467 | sub _resultset { |
468 | my $self = shift; |
469 | |
470 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
471 | { |
472 | select => [$self->{_select}], |
473 | as => [$self->{_as}] |
474 | } |
475 | ); |
476 | } |
477 | |
2bb7b40b |
478 | 1; |
479 | |
480 | =head1 AUTHORS |
481 | |
482 | Luke Saunders <luke.saunders@gmail.com> |
483 | |
eb98561c |
484 | Jess Robinson |
485 | |
2bb7b40b |
486 | =head1 LICENSE |
487 | |
488 | You may distribute this code under the same terms as Perl itself. |
489 | |
490 | =cut |