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1 | package DBIx::Class::ResultSetColumn; |
2 | use strict; |
3 | use warnings; |
4 | use base 'DBIx::Class'; |
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5 | use List::Util; |
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6 | |
7 | =head1 NAME |
8 | |
9 | DBIx::Class::ResultSetColumn - helpful methods for messing |
10 | with a single column of the resultset |
11 | |
12 | =head1 SYNOPSIS |
13 | |
14 | $rs = $schema->resultset('CD')->search({ artist => 'Tool' }); |
15 | $rs_column = $rs->get_column('year'); |
16 | $max_year = $rs_column->max; #returns latest year |
17 | |
18 | =head1 DESCRIPTION |
19 | |
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20 | A convenience class used to perform operations on a specific column of |
21 | a resultset. |
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22 | |
23 | =cut |
24 | |
25 | =head1 METHODS |
26 | |
27 | =head2 new |
28 | |
29 | my $obj = DBIx::Class::ResultSetColumn->new($rs, $column); |
30 | |
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31 | Creates a new resultset column object from the resultset and column |
32 | passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>. |
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33 | |
34 | =cut |
35 | |
36 | sub new { |
37 | my ($class, $rs, $column) = @_; |
38 | $class = ref $class if ref $class; |
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39 | |
40 | $rs->throw_exception("column must be supplied") unless $column; |
41 | |
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42 | my $orig_attrs = $rs->_resolved_attrs; |
43 | my $new_parent_rs = $rs->search_rs; |
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44 | |
45 | # prefetch causes additional columns to be fetched, but we can not just make a new |
46 | # rs via the _resolved_attrs trick - we need to retain the separation between |
bed3a173 |
47 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
48 | # prefetch would otherwise generate. |
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49 | |
50 | my $new_attrs = $new_parent_rs->{attrs} ||= {}; |
51 | $new_attrs->{join} = $rs->_merge_attr( delete $new_attrs->{join}, delete $new_attrs->{prefetch} ); |
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52 | |
152002c4 |
53 | # If $column can be found in the 'as' list of the parent resultset, use the |
54 | # corresponding element of its 'select' list (to keep any custom column |
55 | # definition set up with 'select' or '+select' attrs), otherwise use $column |
56 | # (to create a new column definition on-the-fly). |
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57 | |
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58 | my $as_list = $orig_attrs->{as} || []; |
59 | my $select_list = $orig_attrs->{select} || []; |
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60 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
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61 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
62 | |
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63 | # {collapse} would mean a has_many join was injected, which in turn means |
64 | # we need to group IF WE CAN (only if the column in question is unique) |
65 | if (!$new_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) { |
66 | |
67 | # scan for a constraint that would contain our column only - that'd be proof |
68 | # enough it is unique |
69 | my $constraints = { $rs->result_source->unique_constraints }; |
70 | for my $constraint_columns ( values %$constraints ) { |
71 | |
72 | next unless @$constraint_columns == 1; |
73 | |
74 | my $col = $constraint_columns->[0]; |
75 | my $fqcol = join ('.', $new_attrs->{alias}, $col); |
76 | |
77 | if ($col eq $select or $fqcol eq $select) { |
78 | $new_attrs->{group_by} = [ $select ]; |
79 | last; |
80 | } |
81 | } |
82 | } |
83 | |
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84 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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85 | return $new; |
86 | } |
87 | |
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88 | =head2 as_query (EXPERIMENTAL) |
658fa250 |
89 | |
90 | =over 4 |
91 | |
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92 | =item Arguments: none |
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93 | |
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94 | =item Return Value: \[ $sql, @bind ] |
658fa250 |
95 | |
96 | =back |
97 | |
98 | Returns the SQL query and bind vars associated with the invocant. |
99 | |
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100 | This is generally used as the RHS for a subquery. |
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101 | |
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102 | B<NOTE>: This feature is still experimental. |
103 | |
c7a9d102 |
104 | =cut |
105 | |
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106 | sub as_query { return shift->_resultset->as_query(@_) } |
c7a9d102 |
107 | |
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108 | =head2 next |
109 | |
110 | =over 4 |
111 | |
112 | =item Arguments: none |
113 | |
114 | =item Return Value: $value |
115 | |
116 | =back |
117 | |
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118 | Returns the next value of the column in the resultset (or C<undef> if |
119 | there is none). |
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120 | |
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121 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
122 | one value. |
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123 | |
124 | =cut |
125 | |
126 | sub next { |
127 | my $self = shift; |
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128 | |
129 | # using cursor so we don't inflate anything |
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130 | my ($row) = $self->_resultset->cursor->next; |
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131 | |
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132 | return $row; |
133 | } |
134 | |
135 | =head2 all |
136 | |
137 | =over 4 |
138 | |
139 | =item Arguments: none |
140 | |
141 | =item Return Value: @values |
142 | |
143 | =back |
144 | |
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145 | Returns all values of the column in the resultset (or C<undef> if |
146 | there are none). |
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147 | |
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148 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
149 | than row objects. |
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150 | |
151 | =cut |
152 | |
153 | sub all { |
154 | my $self = shift; |
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155 | |
156 | # using cursor so we don't inflate anything |
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157 | return map { $_->[0] } $self->_resultset->cursor->all; |
158 | } |
159 | |
160 | =head2 reset |
161 | |
162 | =over 4 |
163 | |
164 | =item Arguments: none |
165 | |
166 | =item Return Value: $self |
167 | |
168 | =back |
169 | |
170 | Resets the underlying resultset's cursor, so you can iterate through the |
171 | elements of the column again. |
172 | |
173 | Much like L<DBIx::Class::ResultSet/reset>. |
174 | |
175 | =cut |
176 | |
177 | sub reset { |
178 | my $self = shift; |
179 | $self->_resultset->cursor->reset; |
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180 | return $self; |
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181 | } |
182 | |
183 | =head2 first |
184 | |
185 | =over 4 |
186 | |
187 | =item Arguments: none |
188 | |
189 | =item Return Value: $value |
190 | |
191 | =back |
192 | |
193 | Resets the underlying resultset and returns the next value of the column in the |
194 | resultset (or C<undef> if there is none). |
195 | |
196 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
197 | |
198 | =cut |
199 | |
200 | sub first { |
201 | my $self = shift; |
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202 | |
203 | # using cursor so we don't inflate anything |
204 | $self->_resultset->cursor->reset; |
01dc6781 |
205 | my ($row) = $self->_resultset->cursor->next; |
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206 | |
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207 | return $row; |
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208 | } |
209 | |
210 | =head2 min |
211 | |
212 | =over 4 |
213 | |
214 | =item Arguments: none |
215 | |
216 | =item Return Value: $lowest_value |
217 | |
218 | =back |
219 | |
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220 | my $first_year = $year_col->min(); |
221 | |
222 | Wrapper for ->func. Returns the lowest value of the column in the |
223 | resultset (or C<undef> if there are none). |
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224 | |
225 | =cut |
226 | |
227 | sub min { |
6b051e14 |
228 | return shift->func('MIN'); |
2bb7b40b |
229 | } |
230 | |
4fa7bc22 |
231 | =head2 min_rs |
232 | |
233 | =over 4 |
234 | |
235 | =item Arguments: none |
236 | |
237 | =item Return Value: $resultset |
238 | |
239 | =back |
240 | |
241 | my $rs = $year_col->min_rs(); |
242 | |
243 | Wrapper for ->func_rs for function MIN(). |
244 | |
245 | =cut |
246 | |
247 | sub min_rs { return shift->func_rs('MIN') } |
248 | |
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249 | =head2 max |
250 | |
251 | =over 4 |
252 | |
253 | =item Arguments: none |
254 | |
255 | =item Return Value: $highest_value |
256 | |
257 | =back |
258 | |
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259 | my $last_year = $year_col->max(); |
260 | |
261 | Wrapper for ->func. Returns the highest value of the column in the |
262 | resultset (or C<undef> if there are none). |
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263 | |
264 | =cut |
265 | |
266 | sub max { |
6b051e14 |
267 | return shift->func('MAX'); |
2bb7b40b |
268 | } |
269 | |
4fa7bc22 |
270 | =head2 max_rs |
271 | |
272 | =over 4 |
273 | |
274 | =item Arguments: none |
275 | |
276 | =item Return Value: $resultset |
277 | |
278 | =back |
279 | |
280 | my $rs = $year_col->max_rs(); |
281 | |
282 | Wrapper for ->func_rs for function MAX(). |
283 | |
284 | =cut |
285 | |
286 | sub max_rs { return shift->func_rs('MAX') } |
287 | |
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288 | =head2 sum |
289 | |
290 | =over 4 |
291 | |
292 | =item Arguments: none |
293 | |
294 | =item Return Value: $sum_of_values |
295 | |
296 | =back |
297 | |
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298 | my $total = $prices_col->sum(); |
299 | |
300 | Wrapper for ->func. Returns the sum of all the values in the column of |
301 | the resultset. Use on varchar-like columns at your own risk. |
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302 | |
303 | =cut |
304 | |
305 | sub sum { |
6b051e14 |
306 | return shift->func('SUM'); |
2bb7b40b |
307 | } |
308 | |
4fa7bc22 |
309 | =head2 sum_rs |
310 | |
311 | =over 4 |
312 | |
313 | =item Arguments: none |
314 | |
315 | =item Return Value: $resultset |
316 | |
317 | =back |
318 | |
319 | my $rs = $year_col->sum_rs(); |
320 | |
321 | Wrapper for ->func_rs for function SUM(). |
322 | |
323 | =cut |
324 | |
325 | sub sum_rs { return shift->func_rs('SUM') } |
326 | |
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327 | =head2 func |
328 | |
329 | =over 4 |
330 | |
331 | =item Arguments: $function |
332 | |
333 | =item Return Value: $function_return_value |
334 | |
335 | =back |
336 | |
e8419341 |
337 | $rs = $schema->resultset("CD")->search({}); |
338 | $length = $rs->get_column('title')->func('LENGTH'); |
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339 | |
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340 | Runs a query using the function on the column and returns the |
341 | value. Produces the following SQL: |
342 | |
343 | SELECT LENGTH( title ) FROM cd me |
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344 | |
345 | =cut |
346 | |
347 | sub func { |
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348 | my ($self,$function) = @_; |
4fa7bc22 |
349 | my $cursor = $self->func_rs($function)->cursor; |
d4daee7b |
350 | |
5d62876f |
351 | if( wantarray ) { |
352 | return map { $_->[ 0 ] } $cursor->all; |
353 | } |
354 | |
355 | return ( $cursor->next )[ 0 ]; |
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356 | } |
357 | |
4fa7bc22 |
358 | =head2 func_rs |
359 | |
360 | =over 4 |
361 | |
362 | =item Arguments: $function |
363 | |
364 | =item Return Value: $resultset |
365 | |
366 | =back |
367 | |
368 | Creates the resultset that C<func()> uses to run its query. |
369 | |
370 | =cut |
371 | |
372 | sub func_rs { |
373 | my ($self,$function) = @_; |
374 | return $self->{_parent_resultset}->search( |
375 | undef, { |
376 | select => {$function => $self->{_select}}, |
377 | as => [$self->{_as}], |
378 | }, |
379 | ); |
380 | } |
381 | |
5d1fc7dc |
382 | =head2 throw_exception |
383 | |
384 | See L<DBIx::Class::Schema/throw_exception> for details. |
d4daee7b |
385 | |
5d1fc7dc |
386 | =cut |
d4daee7b |
387 | |
5d1fc7dc |
388 | sub throw_exception { |
389 | my $self=shift; |
390 | if (ref $self && $self->{_parent_resultset}) { |
391 | $self->{_parent_resultset}->throw_exception(@_) |
392 | } else { |
393 | croak(@_); |
394 | } |
395 | } |
396 | |
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397 | # _resultset |
398 | # |
399 | # Arguments: none |
400 | # |
401 | # Return Value: $resultset |
402 | # |
403 | # $year_col->_resultset->next |
404 | # |
405 | # Returns the underlying resultset. Creates it from the parent resultset if |
406 | # necessary. |
b7c79955 |
407 | # |
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408 | sub _resultset { |
409 | my $self = shift; |
410 | |
411 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
412 | { |
413 | select => [$self->{_select}], |
414 | as => [$self->{_as}] |
415 | } |
416 | ); |
417 | } |
418 | |
2bb7b40b |
419 | 1; |
420 | |
421 | =head1 AUTHORS |
422 | |
423 | Luke Saunders <luke.saunders@gmail.com> |
424 | |
eb98561c |
425 | Jess Robinson |
426 | |
2bb7b40b |
427 | =head1 LICENSE |
428 | |
429 | You may distribute this code under the same terms as Perl itself. |
430 | |
431 | =cut |