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1 | package DBIx::Class::ResultSetColumn; |
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2 | |
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3 | use strict; |
4 | use warnings; |
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5 | |
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6 | use base 'DBIx::Class'; |
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7 | |
8 | use DBIx::Class::Exception; |
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9 | use Carp::Clan qw/^DBIx::Class/; |
10 | use namespace::clean; |
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11 | |
12 | # not importing first() as it will clash with our own method |
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13 | use List::Util (); |
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14 | |
15 | =head1 NAME |
16 | |
17 | DBIx::Class::ResultSetColumn - helpful methods for messing |
18 | with a single column of the resultset |
19 | |
20 | =head1 SYNOPSIS |
21 | |
22 | $rs = $schema->resultset('CD')->search({ artist => 'Tool' }); |
23 | $rs_column = $rs->get_column('year'); |
24 | $max_year = $rs_column->max; #returns latest year |
25 | |
26 | =head1 DESCRIPTION |
27 | |
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28 | A convenience class used to perform operations on a specific column of |
29 | a resultset. |
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30 | |
31 | =cut |
32 | |
33 | =head1 METHODS |
34 | |
35 | =head2 new |
36 | |
37 | my $obj = DBIx::Class::ResultSetColumn->new($rs, $column); |
38 | |
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39 | Creates a new resultset column object from the resultset and column |
40 | passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>. |
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41 | |
42 | =cut |
43 | |
44 | sub new { |
45 | my ($class, $rs, $column) = @_; |
46 | $class = ref $class if ref $class; |
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47 | |
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48 | $rs->throw_exception('column must be supplied') unless $column; |
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49 | |
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50 | my $orig_attrs = $rs->_resolved_attrs; |
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51 | my $alias = $rs->current_source_alias; |
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52 | |
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). |
57 | my $as_list = $orig_attrs->{as} || []; |
58 | my $select_list = $orig_attrs->{select} || []; |
59 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
60 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
61 | |
62 | my $new_parent_rs; |
63 | # analyze the order_by, and see if it is done over a function/nonexistentcolumn |
64 | # if this is the case we will need to wrap a subquery since the result of RSC |
65 | # *must* be a single column select |
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66 | my %collist = map |
67 | { $_ => 1, ($_ =~ /\./) ? () : ( "$alias.$_" => 1 ) } |
68 | ($rs->result_source->columns, $column) |
69 | ; |
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70 | if ( |
71 | scalar grep |
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72 | { ! $collist{$_->[0]} } |
73 | ( $rs->result_source->schema->storage->_extract_order_criteria ($orig_attrs->{order_by} ) ) |
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74 | ) { |
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75 | # nuke the prefetch before collapsing to sql |
76 | my $subq_rs = $rs->search; |
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77 | $subq_rs->{attrs}{join} = $subq_rs->_merge_joinpref_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} ); |
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78 | $new_parent_rs = $subq_rs->as_subselect_rs; |
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79 | } |
80 | |
81 | $new_parent_rs ||= $rs->search_rs; |
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82 | my $new_attrs = $new_parent_rs->{attrs} ||= {}; |
83 | |
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84 | # prefetch causes additional columns to be fetched, but we can not just make a new |
85 | # rs via the _resolved_attrs trick - we need to retain the separation between |
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86 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
87 | # prefetch would otherwise generate. |
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88 | $new_attrs->{join} = $rs->_merge_joinpref_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} ); |
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89 | |
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90 | # {collapse} would mean a has_many join was injected, which in turn means |
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91 | # we need to group *IF WE CAN* (only if the column in question is unique) |
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92 | if (!$orig_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) { |
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93 | |
94 | # scan for a constraint that would contain our column only - that'd be proof |
95 | # enough it is unique |
96 | my $constraints = { $rs->result_source->unique_constraints }; |
97 | for my $constraint_columns ( values %$constraints ) { |
98 | |
99 | next unless @$constraint_columns == 1; |
100 | |
101 | my $col = $constraint_columns->[0]; |
102 | my $fqcol = join ('.', $new_attrs->{alias}, $col); |
103 | |
104 | if ($col eq $select or $fqcol eq $select) { |
105 | $new_attrs->{group_by} = [ $select ]; |
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106 | delete $new_attrs->{distinct}; # it is ignored when group_by is present |
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107 | last; |
108 | } |
109 | } |
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110 | |
111 | if (!$new_attrs->{group_by}) { |
112 | carp ( |
113 | "Attempting to retrieve non-unique column '$column' on a resultset containing " |
114 | . 'one-to-many joins will return duplicate results.' |
115 | ); |
116 | } |
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117 | } |
118 | |
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119 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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120 | return $new; |
121 | } |
122 | |
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123 | =head2 as_query |
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124 | |
125 | =over 4 |
126 | |
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127 | =item Arguments: none |
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128 | |
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129 | =item Return Value: \[ $sql, @bind ] |
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130 | |
131 | =back |
132 | |
133 | Returns the SQL query and bind vars associated with the invocant. |
134 | |
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135 | This is generally used as the RHS for a subquery. |
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136 | |
137 | =cut |
138 | |
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139 | sub as_query { return shift->_resultset->as_query(@_) } |
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140 | |
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141 | =head2 next |
142 | |
143 | =over 4 |
144 | |
145 | =item Arguments: none |
146 | |
147 | =item Return Value: $value |
148 | |
149 | =back |
150 | |
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151 | Returns the next value of the column in the resultset (or C<undef> if |
152 | there is none). |
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153 | |
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154 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
155 | one value. |
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156 | |
157 | =cut |
158 | |
159 | sub next { |
160 | my $self = shift; |
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161 | |
162 | # using cursor so we don't inflate anything |
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163 | my ($row) = $self->_resultset->cursor->next; |
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164 | |
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165 | return $row; |
166 | } |
167 | |
168 | =head2 all |
169 | |
170 | =over 4 |
171 | |
172 | =item Arguments: none |
173 | |
174 | =item Return Value: @values |
175 | |
176 | =back |
177 | |
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178 | Returns all values of the column in the resultset (or C<undef> if |
179 | there are none). |
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180 | |
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181 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
182 | than row objects. |
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183 | |
184 | =cut |
185 | |
186 | sub all { |
187 | my $self = shift; |
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188 | |
189 | # using cursor so we don't inflate anything |
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190 | return map { $_->[0] } $self->_resultset->cursor->all; |
191 | } |
192 | |
193 | =head2 reset |
194 | |
195 | =over 4 |
196 | |
197 | =item Arguments: none |
198 | |
199 | =item Return Value: $self |
200 | |
201 | =back |
202 | |
203 | Resets the underlying resultset's cursor, so you can iterate through the |
204 | elements of the column again. |
205 | |
206 | Much like L<DBIx::Class::ResultSet/reset>. |
207 | |
208 | =cut |
209 | |
210 | sub reset { |
211 | my $self = shift; |
212 | $self->_resultset->cursor->reset; |
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213 | return $self; |
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214 | } |
215 | |
216 | =head2 first |
217 | |
218 | =over 4 |
219 | |
220 | =item Arguments: none |
221 | |
222 | =item Return Value: $value |
223 | |
224 | =back |
225 | |
226 | Resets the underlying resultset and returns the next value of the column in the |
227 | resultset (or C<undef> if there is none). |
228 | |
229 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
230 | |
231 | =cut |
232 | |
233 | sub first { |
234 | my $self = shift; |
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235 | |
236 | # using cursor so we don't inflate anything |
237 | $self->_resultset->cursor->reset; |
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238 | my ($row) = $self->_resultset->cursor->next; |
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239 | |
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240 | return $row; |
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241 | } |
242 | |
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243 | =head2 single |
244 | |
245 | =over 4 |
246 | |
247 | =item Arguments: none |
248 | |
249 | =item Return Value: $value |
250 | |
251 | =back |
252 | |
253 | Much like L<DBIx::Class::ResultSet/single> fetches one and only one column |
254 | value using the cursor directly. If additional rows are present a warning |
255 | is issued before discarding the cursor. |
256 | |
257 | =cut |
258 | |
259 | sub single { |
260 | my $self = shift; |
261 | |
262 | my $attrs = $self->_resultset->_resolved_attrs; |
263 | my ($row) = $self->_resultset->result_source->storage->select_single( |
264 | $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs |
265 | ); |
266 | |
267 | return $row; |
268 | } |
269 | |
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270 | =head2 min |
271 | |
272 | =over 4 |
273 | |
274 | =item Arguments: none |
275 | |
276 | =item Return Value: $lowest_value |
277 | |
278 | =back |
279 | |
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280 | my $first_year = $year_col->min(); |
281 | |
282 | Wrapper for ->func. Returns the lowest value of the column in the |
283 | resultset (or C<undef> if there are none). |
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284 | |
285 | =cut |
286 | |
287 | sub min { |
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288 | return shift->func('MIN'); |
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289 | } |
290 | |
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291 | =head2 min_rs |
292 | |
293 | =over 4 |
294 | |
295 | =item Arguments: none |
296 | |
297 | =item Return Value: $resultset |
298 | |
299 | =back |
300 | |
301 | my $rs = $year_col->min_rs(); |
302 | |
303 | Wrapper for ->func_rs for function MIN(). |
304 | |
305 | =cut |
306 | |
307 | sub min_rs { return shift->func_rs('MIN') } |
308 | |
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309 | =head2 max |
310 | |
311 | =over 4 |
312 | |
313 | =item Arguments: none |
314 | |
315 | =item Return Value: $highest_value |
316 | |
317 | =back |
318 | |
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319 | my $last_year = $year_col->max(); |
320 | |
321 | Wrapper for ->func. Returns the highest value of the column in the |
322 | resultset (or C<undef> if there are none). |
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323 | |
324 | =cut |
325 | |
326 | sub max { |
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327 | return shift->func('MAX'); |
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328 | } |
329 | |
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330 | =head2 max_rs |
331 | |
332 | =over 4 |
333 | |
334 | =item Arguments: none |
335 | |
336 | =item Return Value: $resultset |
337 | |
338 | =back |
339 | |
340 | my $rs = $year_col->max_rs(); |
341 | |
342 | Wrapper for ->func_rs for function MAX(). |
343 | |
344 | =cut |
345 | |
346 | sub max_rs { return shift->func_rs('MAX') } |
347 | |
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348 | =head2 sum |
349 | |
350 | =over 4 |
351 | |
352 | =item Arguments: none |
353 | |
354 | =item Return Value: $sum_of_values |
355 | |
356 | =back |
357 | |
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358 | my $total = $prices_col->sum(); |
359 | |
360 | Wrapper for ->func. Returns the sum of all the values in the column of |
361 | the resultset. Use on varchar-like columns at your own risk. |
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362 | |
363 | =cut |
364 | |
365 | sub sum { |
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366 | return shift->func('SUM'); |
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367 | } |
368 | |
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369 | =head2 sum_rs |
370 | |
371 | =over 4 |
372 | |
373 | =item Arguments: none |
374 | |
375 | =item Return Value: $resultset |
376 | |
377 | =back |
378 | |
379 | my $rs = $year_col->sum_rs(); |
380 | |
381 | Wrapper for ->func_rs for function SUM(). |
382 | |
383 | =cut |
384 | |
385 | sub sum_rs { return shift->func_rs('SUM') } |
386 | |
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387 | =head2 func |
388 | |
389 | =over 4 |
390 | |
391 | =item Arguments: $function |
392 | |
393 | =item Return Value: $function_return_value |
394 | |
395 | =back |
396 | |
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397 | $rs = $schema->resultset("CD")->search({}); |
398 | $length = $rs->get_column('title')->func('LENGTH'); |
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399 | |
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400 | Runs a query using the function on the column and returns the |
401 | value. Produces the following SQL: |
402 | |
403 | SELECT LENGTH( title ) FROM cd me |
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404 | |
405 | =cut |
406 | |
407 | sub func { |
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408 | my ($self,$function) = @_; |
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409 | my $cursor = $self->func_rs($function)->cursor; |
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410 | |
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411 | if( wantarray ) { |
412 | return map { $_->[ 0 ] } $cursor->all; |
413 | } |
414 | |
415 | return ( $cursor->next )[ 0 ]; |
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416 | } |
417 | |
4fa7bc22 |
418 | =head2 func_rs |
419 | |
420 | =over 4 |
421 | |
422 | =item Arguments: $function |
423 | |
424 | =item Return Value: $resultset |
425 | |
426 | =back |
427 | |
428 | Creates the resultset that C<func()> uses to run its query. |
429 | |
430 | =cut |
431 | |
432 | sub func_rs { |
433 | my ($self,$function) = @_; |
434 | return $self->{_parent_resultset}->search( |
435 | undef, { |
436 | select => {$function => $self->{_select}}, |
437 | as => [$self->{_as}], |
438 | }, |
439 | ); |
440 | } |
441 | |
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442 | =head2 throw_exception |
443 | |
444 | See L<DBIx::Class::Schema/throw_exception> for details. |
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445 | |
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446 | =cut |
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447 | |
5d1fc7dc |
448 | sub throw_exception { |
449 | my $self=shift; |
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450 | |
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451 | if (ref $self && $self->{_parent_resultset}) { |
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452 | $self->{_parent_resultset}->throw_exception(@_); |
453 | } |
454 | else { |
455 | DBIx::Class::Exception->throw(@_); |
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456 | } |
457 | } |
458 | |
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459 | # _resultset |
460 | # |
461 | # Arguments: none |
462 | # |
463 | # Return Value: $resultset |
464 | # |
465 | # $year_col->_resultset->next |
466 | # |
467 | # Returns the underlying resultset. Creates it from the parent resultset if |
468 | # necessary. |
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469 | # |
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470 | sub _resultset { |
471 | my $self = shift; |
472 | |
473 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
474 | { |
475 | select => [$self->{_select}], |
476 | as => [$self->{_as}] |
477 | } |
478 | ); |
479 | } |
480 | |
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481 | 1; |
482 | |
483 | =head1 AUTHORS |
484 | |
485 | Luke Saunders <luke.saunders@gmail.com> |
486 | |
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487 | Jess Robinson |
488 | |
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489 | =head1 LICENSE |
490 | |
491 | You may distribute this code under the same terms as Perl itself. |
492 | |
493 | =cut |