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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 | use DBIx::Class::Carp; |
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8 | use DBIx::Class::Exception; |
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9 | |
10 | # not importing first() as it will clash with our own method |
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11 | use List::Util (); |
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12 | |
13 | =head1 NAME |
14 | |
15 | DBIx::Class::ResultSetColumn - helpful methods for messing |
16 | with a single column of the resultset |
17 | |
18 | =head1 SYNOPSIS |
19 | |
20 | $rs = $schema->resultset('CD')->search({ artist => 'Tool' }); |
21 | $rs_column = $rs->get_column('year'); |
22 | $max_year = $rs_column->max; #returns latest year |
23 | |
24 | =head1 DESCRIPTION |
25 | |
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26 | A convenience class used to perform operations on a specific column of |
27 | a resultset. |
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28 | |
29 | =cut |
30 | |
31 | =head1 METHODS |
32 | |
33 | =head2 new |
34 | |
35 | my $obj = DBIx::Class::ResultSetColumn->new($rs, $column); |
36 | |
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37 | Creates a new resultset column object from the resultset and column |
38 | passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>. |
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39 | |
40 | =cut |
41 | |
42 | sub new { |
43 | my ($class, $rs, $column) = @_; |
44 | $class = ref $class if ref $class; |
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45 | |
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46 | $rs->throw_exception('column must be supplied') unless $column; |
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47 | |
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48 | my $orig_attrs = $rs->_resolved_attrs; |
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49 | my $alias = $rs->current_source_alias; |
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50 | my $rsrc = $rs->result_source; |
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51 | |
52 | # If $column can be found in the 'as' list of the parent resultset, use the |
53 | # corresponding element of its 'select' list (to keep any custom column |
54 | # definition set up with 'select' or '+select' attrs), otherwise use $column |
55 | # (to create a new column definition on-the-fly). |
56 | my $as_list = $orig_attrs->{as} || []; |
57 | my $select_list = $orig_attrs->{select} || []; |
58 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
59 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
60 | |
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61 | my ($new_parent_rs, $colmap); |
62 | for ($rsrc->columns, $column) { |
63 | if ($_ =~ /^ \Q$alias\E \. ([^\.]+) $ /x) { |
64 | $colmap->{$_} = $1; |
65 | } |
66 | elsif ($_ !~ /\./) { |
67 | $colmap->{"$alias.$_"} = $_; |
68 | $colmap->{$_} = $_; |
69 | } |
70 | } |
71 | |
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72 | # analyze the order_by, and see if it is done over a function/nonexistentcolumn |
73 | # if this is the case we will need to wrap a subquery since the result of RSC |
74 | # *must* be a single column select |
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75 | if ( |
76 | scalar grep |
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77 | { ! exists $colmap->{$_->[0]} } |
78 | ( $rsrc->schema->storage->_extract_order_criteria ($orig_attrs->{order_by} ) ) |
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79 | ) { |
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80 | # nuke the prefetch before collapsing to sql |
81 | my $subq_rs = $rs->search; |
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82 | $subq_rs->{attrs}{join} = $subq_rs->_merge_joinpref_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} ); |
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83 | $new_parent_rs = $subq_rs->as_subselect_rs; |
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84 | } |
85 | |
86 | $new_parent_rs ||= $rs->search_rs; |
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87 | my $new_attrs = $new_parent_rs->{attrs} ||= {}; |
88 | |
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89 | # prefetch causes additional columns to be fetched, but we can not just make a new |
90 | # rs via the _resolved_attrs trick - we need to retain the separation between |
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91 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
92 | # prefetch would otherwise generate. |
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93 | $new_attrs->{join} = $rs->_merge_joinpref_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} ); |
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94 | |
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95 | # {collapse} would mean a has_many join was injected, which in turn means |
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96 | # we need to group *IF WE CAN* (only if the column in question is unique) |
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97 | if (!$orig_attrs->{group_by} && keys %{$orig_attrs->{collapse}}) { |
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98 | |
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99 | if ($colmap->{$select} and $rsrc->_identifying_column_set([$colmap->{$select}])) { |
100 | $new_attrs->{group_by} = [ $select ]; |
101 | delete $new_attrs->{distinct}; # it is ignored when group_by is present |
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102 | } |
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103 | else { |
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104 | carp ( |
105 | "Attempting to retrieve non-unique column '$column' on a resultset containing " |
106 | . 'one-to-many joins will return duplicate results.' |
107 | ); |
108 | } |
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109 | } |
110 | |
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111 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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112 | return $new; |
113 | } |
114 | |
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115 | =head2 as_query |
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116 | |
117 | =over 4 |
118 | |
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119 | =item Arguments: none |
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120 | |
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121 | =item Return Value: \[ $sql, L<@bind_values|DBIx::Class::ResultSet/DBIC BIND VALUES> ] |
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122 | |
123 | =back |
124 | |
125 | Returns the SQL query and bind vars associated with the invocant. |
126 | |
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127 | This is generally used as the RHS for a subquery. |
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128 | |
129 | =cut |
130 | |
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131 | sub as_query { return shift->_resultset->as_query(@_) } |
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132 | |
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133 | =head2 next |
134 | |
135 | =over 4 |
136 | |
137 | =item Arguments: none |
138 | |
139 | =item Return Value: $value |
140 | |
141 | =back |
142 | |
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143 | Returns the next value of the column in the resultset (or C<undef> if |
144 | there is none). |
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145 | |
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146 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
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147 | one value. |
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148 | |
149 | =cut |
150 | |
151 | sub next { |
152 | my $self = shift; |
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153 | |
154 | # using cursor so we don't inflate anything |
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155 | my ($row) = $self->_resultset->cursor->next; |
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156 | |
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157 | return $row; |
158 | } |
159 | |
160 | =head2 all |
161 | |
162 | =over 4 |
163 | |
164 | =item Arguments: none |
165 | |
166 | =item Return Value: @values |
167 | |
168 | =back |
169 | |
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170 | Returns all values of the column in the resultset (or C<undef> if |
171 | there are none). |
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172 | |
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173 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
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174 | than result objects. |
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175 | |
176 | =cut |
177 | |
178 | sub all { |
179 | my $self = shift; |
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180 | |
181 | # using cursor so we don't inflate anything |
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182 | return map { $_->[0] } $self->_resultset->cursor->all; |
183 | } |
184 | |
185 | =head2 reset |
186 | |
187 | =over 4 |
188 | |
189 | =item Arguments: none |
190 | |
191 | =item Return Value: $self |
192 | |
193 | =back |
194 | |
195 | Resets the underlying resultset's cursor, so you can iterate through the |
196 | elements of the column again. |
197 | |
198 | Much like L<DBIx::Class::ResultSet/reset>. |
199 | |
200 | =cut |
201 | |
202 | sub reset { |
203 | my $self = shift; |
204 | $self->_resultset->cursor->reset; |
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205 | return $self; |
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206 | } |
207 | |
208 | =head2 first |
209 | |
210 | =over 4 |
211 | |
212 | =item Arguments: none |
213 | |
214 | =item Return Value: $value |
215 | |
216 | =back |
217 | |
218 | Resets the underlying resultset and returns the next value of the column in the |
219 | resultset (or C<undef> if there is none). |
220 | |
221 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
222 | |
223 | =cut |
224 | |
225 | sub first { |
226 | my $self = shift; |
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227 | |
228 | # using cursor so we don't inflate anything |
229 | $self->_resultset->cursor->reset; |
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230 | my ($row) = $self->_resultset->cursor->next; |
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231 | |
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232 | return $row; |
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233 | } |
234 | |
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235 | =head2 single |
236 | |
237 | =over 4 |
238 | |
239 | =item Arguments: none |
240 | |
241 | =item Return Value: $value |
242 | |
243 | =back |
244 | |
245 | Much like L<DBIx::Class::ResultSet/single> fetches one and only one column |
246 | value using the cursor directly. If additional rows are present a warning |
247 | is issued before discarding the cursor. |
248 | |
249 | =cut |
250 | |
251 | sub single { |
252 | my $self = shift; |
253 | |
254 | my $attrs = $self->_resultset->_resolved_attrs; |
255 | my ($row) = $self->_resultset->result_source->storage->select_single( |
256 | $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs |
257 | ); |
258 | |
259 | return $row; |
260 | } |
261 | |
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262 | =head2 min |
263 | |
264 | =over 4 |
265 | |
266 | =item Arguments: none |
267 | |
268 | =item Return Value: $lowest_value |
269 | |
270 | =back |
271 | |
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272 | my $first_year = $year_col->min(); |
273 | |
274 | Wrapper for ->func. Returns the lowest value of the column in the |
275 | resultset (or C<undef> if there are none). |
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276 | |
277 | =cut |
278 | |
279 | sub min { |
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280 | return shift->func('MIN'); |
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281 | } |
282 | |
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283 | =head2 min_rs |
284 | |
285 | =over 4 |
286 | |
287 | =item Arguments: none |
288 | |
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289 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
4fa7bc22 |
290 | |
291 | =back |
292 | |
293 | my $rs = $year_col->min_rs(); |
294 | |
295 | Wrapper for ->func_rs for function MIN(). |
296 | |
297 | =cut |
298 | |
299 | sub min_rs { return shift->func_rs('MIN') } |
300 | |
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301 | =head2 max |
302 | |
303 | =over 4 |
304 | |
305 | =item Arguments: none |
306 | |
307 | =item Return Value: $highest_value |
308 | |
309 | =back |
310 | |
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311 | my $last_year = $year_col->max(); |
312 | |
313 | Wrapper for ->func. Returns the highest value of the column in the |
314 | resultset (or C<undef> if there are none). |
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315 | |
316 | =cut |
317 | |
318 | sub max { |
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319 | return shift->func('MAX'); |
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320 | } |
321 | |
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322 | =head2 max_rs |
323 | |
324 | =over 4 |
325 | |
326 | =item Arguments: none |
327 | |
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328 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
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329 | |
330 | =back |
331 | |
332 | my $rs = $year_col->max_rs(); |
333 | |
334 | Wrapper for ->func_rs for function MAX(). |
335 | |
336 | =cut |
337 | |
338 | sub max_rs { return shift->func_rs('MAX') } |
339 | |
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340 | =head2 sum |
341 | |
342 | =over 4 |
343 | |
344 | =item Arguments: none |
345 | |
346 | =item Return Value: $sum_of_values |
347 | |
348 | =back |
349 | |
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350 | my $total = $prices_col->sum(); |
351 | |
352 | Wrapper for ->func. Returns the sum of all the values in the column of |
353 | the resultset. Use on varchar-like columns at your own risk. |
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354 | |
355 | =cut |
356 | |
357 | sub sum { |
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358 | return shift->func('SUM'); |
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359 | } |
360 | |
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361 | =head2 sum_rs |
362 | |
363 | =over 4 |
364 | |
365 | =item Arguments: none |
366 | |
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367 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
4fa7bc22 |
368 | |
369 | =back |
370 | |
371 | my $rs = $year_col->sum_rs(); |
372 | |
373 | Wrapper for ->func_rs for function SUM(). |
374 | |
375 | =cut |
376 | |
377 | sub sum_rs { return shift->func_rs('SUM') } |
378 | |
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379 | =head2 func |
380 | |
381 | =over 4 |
382 | |
383 | =item Arguments: $function |
384 | |
385 | =item Return Value: $function_return_value |
386 | |
387 | =back |
388 | |
e8419341 |
389 | $rs = $schema->resultset("CD")->search({}); |
390 | $length = $rs->get_column('title')->func('LENGTH'); |
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391 | |
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392 | Runs a query using the function on the column and returns the |
393 | value. Produces the following SQL: |
394 | |
395 | SELECT LENGTH( title ) FROM cd me |
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396 | |
397 | =cut |
398 | |
399 | sub func { |
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400 | my ($self,$function) = @_; |
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401 | my $cursor = $self->func_rs($function)->cursor; |
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402 | |
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403 | if( wantarray ) { |
404 | return map { $_->[ 0 ] } $cursor->all; |
405 | } |
406 | |
407 | return ( $cursor->next )[ 0 ]; |
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408 | } |
409 | |
4fa7bc22 |
410 | =head2 func_rs |
411 | |
412 | =over 4 |
413 | |
414 | =item Arguments: $function |
415 | |
fb13a49f |
416 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
4fa7bc22 |
417 | |
418 | =back |
419 | |
420 | Creates the resultset that C<func()> uses to run its query. |
421 | |
422 | =cut |
423 | |
424 | sub func_rs { |
425 | my ($self,$function) = @_; |
426 | return $self->{_parent_resultset}->search( |
427 | undef, { |
428 | select => {$function => $self->{_select}}, |
429 | as => [$self->{_as}], |
430 | }, |
431 | ); |
432 | } |
433 | |
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434 | =head2 throw_exception |
435 | |
436 | See L<DBIx::Class::Schema/throw_exception> for details. |
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437 | |
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438 | =cut |
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439 | |
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440 | sub throw_exception { |
441 | my $self=shift; |
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442 | |
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443 | if (ref $self && $self->{_parent_resultset}) { |
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444 | $self->{_parent_resultset}->throw_exception(@_); |
445 | } |
446 | else { |
447 | DBIx::Class::Exception->throw(@_); |
5d1fc7dc |
448 | } |
449 | } |
450 | |
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451 | # _resultset |
452 | # |
453 | # Arguments: none |
454 | # |
455 | # Return Value: $resultset |
456 | # |
457 | # $year_col->_resultset->next |
458 | # |
459 | # Returns the underlying resultset. Creates it from the parent resultset if |
460 | # necessary. |
b7c79955 |
461 | # |
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462 | sub _resultset { |
463 | my $self = shift; |
464 | |
465 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
466 | { |
467 | select => [$self->{_select}], |
468 | as => [$self->{_as}] |
469 | } |
470 | ); |
471 | } |
472 | |
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473 | 1; |
474 | |
0c11ad0e |
475 | =head1 AUTHOR AND CONTRIBUTORS |
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476 | |
0c11ad0e |
477 | See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class |
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478 | |
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479 | =head1 LICENSE |
480 | |
481 | You may distribute this code under the same terms as Perl itself. |
482 | |
483 | =cut |