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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 | |
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8 | use Carp::Clan qw/^DBIx::Class/; |
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9 | use DBIx::Class::Exception; |
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10 | use List::Util; |
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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 | |
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25 | A convenience class used to perform operations on a specific column of |
26 | a resultset. |
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27 | |
28 | =cut |
29 | |
30 | =head1 METHODS |
31 | |
32 | =head2 new |
33 | |
34 | my $obj = DBIx::Class::ResultSetColumn->new($rs, $column); |
35 | |
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36 | Creates a new resultset column object from the resultset and column |
37 | passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>. |
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38 | |
39 | =cut |
40 | |
41 | sub new { |
42 | my ($class, $rs, $column) = @_; |
43 | $class = ref $class if ref $class; |
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44 | |
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45 | $rs->throw_exception('column must be supplied') unless $column; |
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46 | |
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47 | my $orig_attrs = $rs->_resolved_attrs; |
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48 | |
49 | # If $column can be found in the 'as' list of the parent resultset, use the |
50 | # corresponding element of its 'select' list (to keep any custom column |
51 | # definition set up with 'select' or '+select' attrs), otherwise use $column |
52 | # (to create a new column definition on-the-fly). |
53 | my $as_list = $orig_attrs->{as} || []; |
54 | my $select_list = $orig_attrs->{select} || []; |
55 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
56 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
57 | |
58 | my $new_parent_rs; |
59 | # analyze the order_by, and see if it is done over a function/nonexistentcolumn |
60 | # if this is the case we will need to wrap a subquery since the result of RSC |
61 | # *must* be a single column select |
62 | my %collist = map { $_ => 1 } ($rs->result_source->columns, $column); |
63 | if ( |
64 | scalar grep |
65 | { ! $collist{$_} } |
66 | ( $rs->result_source->schema->storage->_parse_order_by ($orig_attrs->{order_by} ) ) |
67 | ) { |
68 | my $alias = $rs->current_source_alias; |
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69 | # nuke the prefetch before collapsing to sql |
70 | my $subq_rs = $rs->search; |
71 | $subq_rs->{attrs}{join} = $subq_rs->_merge_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} ); |
72 | |
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73 | $new_parent_rs = $rs->result_source->resultset->search ( {}, { |
74 | alias => $alias, |
75 | from => [{ |
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76 | $alias => $subq_rs->as_query, |
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77 | -alias => $alias, |
78 | -source_handle => $rs->result_source->handle, |
79 | }] |
80 | }); |
81 | } |
82 | |
83 | $new_parent_rs ||= $rs->search_rs; |
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84 | my $new_attrs = $new_parent_rs->{attrs} ||= {}; |
85 | |
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86 | # FIXME - this should go away when the chaining branch is merged |
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87 | # since what we do is actually chain to the original resultset, we need to throw |
88 | # away all selectors (otherwise they'll chain) |
89 | delete $new_attrs->{$_} for (qw/columns +columns select +select as +as cols include_columns/); |
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90 | |
91 | # prefetch causes additional columns to be fetched, but we can not just make a new |
92 | # rs via the _resolved_attrs trick - we need to retain the separation between |
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93 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
94 | # prefetch would otherwise generate. |
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95 | $new_attrs->{join} = $rs->_merge_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} ); |
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96 | |
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97 | # {collapse} would mean a has_many join was injected, which in turn means |
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98 | # we need to group *IF WE CAN* (only if the column in question is unique) |
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99 | if (!$new_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) { |
100 | |
101 | # scan for a constraint that would contain our column only - that'd be proof |
102 | # enough it is unique |
103 | my $constraints = { $rs->result_source->unique_constraints }; |
104 | for my $constraint_columns ( values %$constraints ) { |
105 | |
106 | next unless @$constraint_columns == 1; |
107 | |
108 | my $col = $constraint_columns->[0]; |
109 | my $fqcol = join ('.', $new_attrs->{alias}, $col); |
110 | |
111 | if ($col eq $select or $fqcol eq $select) { |
112 | $new_attrs->{group_by} = [ $select ]; |
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113 | delete $new_attrs->{distinct}; # it is ignored when group_by is present |
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114 | last; |
115 | } |
116 | } |
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117 | |
118 | if (!$new_attrs->{group_by}) { |
119 | carp ( |
120 | "Attempting to retrieve non-unique column '$column' on a resultset containing " |
121 | . 'one-to-many joins will return duplicate results.' |
122 | ); |
123 | } |
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124 | } |
125 | |
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126 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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127 | return $new; |
128 | } |
129 | |
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130 | =head2 as_query |
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131 | |
132 | =over 4 |
133 | |
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134 | =item Arguments: none |
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135 | |
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136 | =item Return Value: \[ $sql, @bind ] |
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137 | |
138 | =back |
139 | |
140 | Returns the SQL query and bind vars associated with the invocant. |
141 | |
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142 | This is generally used as the RHS for a subquery. |
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143 | |
144 | =cut |
145 | |
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146 | sub as_query { return shift->_resultset->as_query(@_) } |
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147 | |
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148 | =head2 next |
149 | |
150 | =over 4 |
151 | |
152 | =item Arguments: none |
153 | |
154 | =item Return Value: $value |
155 | |
156 | =back |
157 | |
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158 | Returns the next value of the column in the resultset (or C<undef> if |
159 | there is none). |
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160 | |
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161 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
162 | one value. |
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163 | |
164 | =cut |
165 | |
166 | sub next { |
167 | my $self = shift; |
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168 | |
169 | # using cursor so we don't inflate anything |
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170 | my ($row) = $self->_resultset->cursor->next; |
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171 | |
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172 | return $row; |
173 | } |
174 | |
175 | =head2 all |
176 | |
177 | =over 4 |
178 | |
179 | =item Arguments: none |
180 | |
181 | =item Return Value: @values |
182 | |
183 | =back |
184 | |
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185 | Returns all values of the column in the resultset (or C<undef> if |
186 | there are none). |
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187 | |
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188 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
189 | than row objects. |
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190 | |
191 | =cut |
192 | |
193 | sub all { |
194 | my $self = shift; |
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195 | |
196 | # using cursor so we don't inflate anything |
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197 | return map { $_->[0] } $self->_resultset->cursor->all; |
198 | } |
199 | |
200 | =head2 reset |
201 | |
202 | =over 4 |
203 | |
204 | =item Arguments: none |
205 | |
206 | =item Return Value: $self |
207 | |
208 | =back |
209 | |
210 | Resets the underlying resultset's cursor, so you can iterate through the |
211 | elements of the column again. |
212 | |
213 | Much like L<DBIx::Class::ResultSet/reset>. |
214 | |
215 | =cut |
216 | |
217 | sub reset { |
218 | my $self = shift; |
219 | $self->_resultset->cursor->reset; |
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220 | return $self; |
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221 | } |
222 | |
223 | =head2 first |
224 | |
225 | =over 4 |
226 | |
227 | =item Arguments: none |
228 | |
229 | =item Return Value: $value |
230 | |
231 | =back |
232 | |
233 | Resets the underlying resultset and returns the next value of the column in the |
234 | resultset (or C<undef> if there is none). |
235 | |
236 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
237 | |
238 | =cut |
239 | |
240 | sub first { |
241 | my $self = shift; |
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242 | |
243 | # using cursor so we don't inflate anything |
244 | $self->_resultset->cursor->reset; |
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245 | my ($row) = $self->_resultset->cursor->next; |
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246 | |
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247 | return $row; |
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248 | } |
249 | |
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250 | =head2 single |
251 | |
252 | =over 4 |
253 | |
254 | =item Arguments: none |
255 | |
256 | =item Return Value: $value |
257 | |
258 | =back |
259 | |
260 | Much like L<DBIx::Class::ResultSet/single> fetches one and only one column |
261 | value using the cursor directly. If additional rows are present a warning |
262 | is issued before discarding the cursor. |
263 | |
264 | =cut |
265 | |
266 | sub single { |
267 | my $self = shift; |
268 | |
269 | my $attrs = $self->_resultset->_resolved_attrs; |
270 | my ($row) = $self->_resultset->result_source->storage->select_single( |
271 | $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs |
272 | ); |
273 | |
274 | return $row; |
275 | } |
276 | |
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277 | =head2 min |
278 | |
279 | =over 4 |
280 | |
281 | =item Arguments: none |
282 | |
283 | =item Return Value: $lowest_value |
284 | |
285 | =back |
286 | |
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287 | my $first_year = $year_col->min(); |
288 | |
289 | Wrapper for ->func. Returns the lowest value of the column in the |
290 | resultset (or C<undef> if there are none). |
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291 | |
292 | =cut |
293 | |
294 | sub min { |
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295 | return shift->func('MIN'); |
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296 | } |
297 | |
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298 | =head2 min_rs |
299 | |
300 | =over 4 |
301 | |
302 | =item Arguments: none |
303 | |
304 | =item Return Value: $resultset |
305 | |
306 | =back |
307 | |
308 | my $rs = $year_col->min_rs(); |
309 | |
310 | Wrapper for ->func_rs for function MIN(). |
311 | |
312 | =cut |
313 | |
314 | sub min_rs { return shift->func_rs('MIN') } |
315 | |
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316 | =head2 max |
317 | |
318 | =over 4 |
319 | |
320 | =item Arguments: none |
321 | |
322 | =item Return Value: $highest_value |
323 | |
324 | =back |
325 | |
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326 | my $last_year = $year_col->max(); |
327 | |
328 | Wrapper for ->func. Returns the highest value of the column in the |
329 | resultset (or C<undef> if there are none). |
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330 | |
331 | =cut |
332 | |
333 | sub max { |
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334 | return shift->func('MAX'); |
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335 | } |
336 | |
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337 | =head2 max_rs |
338 | |
339 | =over 4 |
340 | |
341 | =item Arguments: none |
342 | |
343 | =item Return Value: $resultset |
344 | |
345 | =back |
346 | |
347 | my $rs = $year_col->max_rs(); |
348 | |
349 | Wrapper for ->func_rs for function MAX(). |
350 | |
351 | =cut |
352 | |
353 | sub max_rs { return shift->func_rs('MAX') } |
354 | |
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355 | =head2 sum |
356 | |
357 | =over 4 |
358 | |
359 | =item Arguments: none |
360 | |
361 | =item Return Value: $sum_of_values |
362 | |
363 | =back |
364 | |
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365 | my $total = $prices_col->sum(); |
366 | |
367 | Wrapper for ->func. Returns the sum of all the values in the column of |
368 | the resultset. Use on varchar-like columns at your own risk. |
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369 | |
370 | =cut |
371 | |
372 | sub sum { |
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373 | return shift->func('SUM'); |
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374 | } |
375 | |
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376 | =head2 sum_rs |
377 | |
378 | =over 4 |
379 | |
380 | =item Arguments: none |
381 | |
382 | =item Return Value: $resultset |
383 | |
384 | =back |
385 | |
386 | my $rs = $year_col->sum_rs(); |
387 | |
388 | Wrapper for ->func_rs for function SUM(). |
389 | |
390 | =cut |
391 | |
392 | sub sum_rs { return shift->func_rs('SUM') } |
393 | |
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394 | =head2 func |
395 | |
396 | =over 4 |
397 | |
398 | =item Arguments: $function |
399 | |
400 | =item Return Value: $function_return_value |
401 | |
402 | =back |
403 | |
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404 | $rs = $schema->resultset("CD")->search({}); |
405 | $length = $rs->get_column('title')->func('LENGTH'); |
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406 | |
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407 | Runs a query using the function on the column and returns the |
408 | value. Produces the following SQL: |
409 | |
410 | SELECT LENGTH( title ) FROM cd me |
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411 | |
412 | =cut |
413 | |
414 | sub func { |
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415 | my ($self,$function) = @_; |
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416 | my $cursor = $self->func_rs($function)->cursor; |
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417 | |
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418 | if( wantarray ) { |
419 | return map { $_->[ 0 ] } $cursor->all; |
420 | } |
421 | |
422 | return ( $cursor->next )[ 0 ]; |
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423 | } |
424 | |
4fa7bc22 |
425 | =head2 func_rs |
426 | |
427 | =over 4 |
428 | |
429 | =item Arguments: $function |
430 | |
431 | =item Return Value: $resultset |
432 | |
433 | =back |
434 | |
435 | Creates the resultset that C<func()> uses to run its query. |
436 | |
437 | =cut |
438 | |
439 | sub func_rs { |
440 | my ($self,$function) = @_; |
441 | return $self->{_parent_resultset}->search( |
442 | undef, { |
443 | select => {$function => $self->{_select}}, |
444 | as => [$self->{_as}], |
445 | }, |
446 | ); |
447 | } |
448 | |
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449 | =head2 throw_exception |
450 | |
451 | See L<DBIx::Class::Schema/throw_exception> for details. |
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452 | |
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453 | =cut |
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454 | |
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455 | sub throw_exception { |
456 | my $self=shift; |
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457 | |
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458 | if (ref $self && $self->{_parent_resultset}) { |
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459 | $self->{_parent_resultset}->throw_exception(@_); |
460 | } |
461 | else { |
462 | DBIx::Class::Exception->throw(@_); |
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463 | } |
464 | } |
465 | |
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466 | # _resultset |
467 | # |
468 | # Arguments: none |
469 | # |
470 | # Return Value: $resultset |
471 | # |
472 | # $year_col->_resultset->next |
473 | # |
474 | # Returns the underlying resultset. Creates it from the parent resultset if |
475 | # necessary. |
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476 | # |
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477 | sub _resultset { |
478 | my $self = shift; |
479 | |
480 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
481 | { |
482 | select => [$self->{_select}], |
483 | as => [$self->{_as}] |
484 | } |
485 | ); |
486 | } |
487 | |
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488 | 1; |
489 | |
490 | =head1 AUTHORS |
491 | |
492 | Luke Saunders <luke.saunders@gmail.com> |
493 | |
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494 | Jess Robinson |
495 | |
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496 | =head1 LICENSE |
497 | |
498 | You may distribute this code under the same terms as Perl itself. |
499 | |
500 | =cut |