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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::_Util 'fail_on_internal_wantarray'; |
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9 | use namespace::clean; |
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10 | |
11 | # not importing first() as it will clash with our own method |
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12 | use List::Util (); |
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13 | |
14 | =head1 NAME |
15 | |
16 | DBIx::Class::ResultSetColumn - helpful methods for messing |
17 | with a single column of the resultset |
18 | |
19 | =head1 SYNOPSIS |
20 | |
21 | $rs = $schema->resultset('CD')->search({ artist => 'Tool' }); |
22 | $rs_column = $rs->get_column('year'); |
23 | $max_year = $rs_column->max; #returns latest year |
24 | |
25 | =head1 DESCRIPTION |
26 | |
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27 | A convenience class used to perform operations on a specific column of |
28 | a resultset. |
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29 | |
30 | =cut |
31 | |
32 | =head1 METHODS |
33 | |
34 | =head2 new |
35 | |
36 | my $obj = DBIx::Class::ResultSetColumn->new($rs, $column); |
37 | |
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38 | Creates a new resultset column object from the resultset and column |
39 | passed as params. Used internally by L<DBIx::Class::ResultSet/get_column>. |
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40 | |
41 | =cut |
42 | |
43 | sub new { |
44 | my ($class, $rs, $column) = @_; |
45 | $class = ref $class if ref $class; |
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46 | |
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47 | $rs->throw_exception('column must be supplied') unless $column; |
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48 | |
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49 | my $orig_attrs = $rs->_resolved_attrs; |
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50 | my $alias = $rs->current_source_alias; |
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51 | my $rsrc = $rs->result_source; |
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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] : $column; |
61 | |
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62 | my ($new_parent_rs, $colmap); |
63 | for ($rsrc->columns, $column) { |
64 | if ($_ =~ /^ \Q$alias\E \. ([^\.]+) $ /x) { |
65 | $colmap->{$_} = $1; |
66 | } |
67 | elsif ($_ !~ /\./) { |
68 | $colmap->{"$alias.$_"} = $_; |
69 | $colmap->{$_} = $_; |
70 | } |
71 | } |
72 | |
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73 | # analyze the order_by, and see if it is done over a function/nonexistentcolumn |
74 | # if this is the case we will need to wrap a subquery since the result of RSC |
75 | # *must* be a single column select |
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76 | if ( |
77 | scalar grep |
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78 | { ! exists $colmap->{$_->[0]} } |
79 | ( $rsrc->schema->storage->_extract_order_criteria ($orig_attrs->{order_by} ) ) |
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80 | ) { |
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81 | # nuke the prefetch before collapsing to sql |
82 | my $subq_rs = $rs->search; |
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83 | $subq_rs->{attrs}{join} = $subq_rs->_merge_joinpref_attr( $subq_rs->{attrs}{join}, delete $subq_rs->{attrs}{prefetch} ); |
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84 | $new_parent_rs = $subq_rs->as_subselect_rs; |
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85 | } |
86 | |
87 | $new_parent_rs ||= $rs->search_rs; |
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88 | my $new_attrs = $new_parent_rs->{attrs} ||= {}; |
89 | |
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90 | # prefetch causes additional columns to be fetched, but we can not just make a new |
91 | # rs via the _resolved_attrs trick - we need to retain the separation between |
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92 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
93 | # prefetch would otherwise generate. |
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94 | $new_attrs->{join} = $rs->_merge_joinpref_attr( $new_attrs->{join}, delete $new_attrs->{prefetch} ); |
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95 | |
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96 | # {collapse} would mean a has_many join was injected, which in turn means |
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97 | # we need to group *IF WE CAN* (only if the column in question is unique) |
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98 | if (!$orig_attrs->{group_by} && $orig_attrs->{collapse}) { |
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99 | |
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100 | if ($colmap->{$select} and $rsrc->_identifying_column_set([$colmap->{$select}])) { |
101 | $new_attrs->{group_by} = [ $select ]; |
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102 | delete @{$new_attrs}{qw(distinct _grouped_by_distinct)}; # it is ignored when group_by is present |
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103 | } |
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104 | else { |
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105 | carp ( |
106 | "Attempting to retrieve non-unique column '$column' on a resultset containing " |
107 | . 'one-to-many joins will return duplicate results.' |
108 | ); |
109 | } |
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110 | } |
111 | |
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112 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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113 | return $new; |
114 | } |
115 | |
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116 | =head2 as_query |
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117 | |
118 | =over 4 |
119 | |
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120 | =item Arguments: none |
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121 | |
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122 | =item Return Value: \[ $sql, L<@bind_values|DBIx::Class::ResultSet/DBIC BIND VALUES> ] |
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123 | |
124 | =back |
125 | |
126 | Returns the SQL query and bind vars associated with the invocant. |
127 | |
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128 | This is generally used as the RHS for a subquery. |
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129 | |
130 | =cut |
131 | |
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132 | sub as_query { return shift->_resultset->as_query(@_) } |
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133 | |
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134 | =head2 next |
135 | |
136 | =over 4 |
137 | |
138 | =item Arguments: none |
139 | |
140 | =item Return Value: $value |
141 | |
142 | =back |
143 | |
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144 | Returns the next value of the column in the resultset (or C<undef> if |
145 | there is none). |
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146 | |
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147 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
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148 | one value. |
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149 | |
150 | =cut |
151 | |
152 | sub next { |
153 | my $self = shift; |
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154 | |
155 | # using cursor so we don't inflate anything |
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156 | my ($row) = $self->_resultset->cursor->next; |
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157 | |
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158 | return $row; |
159 | } |
160 | |
161 | =head2 all |
162 | |
163 | =over 4 |
164 | |
165 | =item Arguments: none |
166 | |
167 | =item Return Value: @values |
168 | |
169 | =back |
170 | |
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171 | Returns all values of the column in the resultset (or C<undef> if |
172 | there are none). |
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173 | |
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174 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
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175 | than result objects. |
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176 | |
177 | =cut |
178 | |
179 | sub all { |
180 | my $self = shift; |
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181 | |
182 | # using cursor so we don't inflate anything |
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183 | return map { $_->[0] } $self->_resultset->cursor->all; |
184 | } |
185 | |
186 | =head2 reset |
187 | |
188 | =over 4 |
189 | |
190 | =item Arguments: none |
191 | |
192 | =item Return Value: $self |
193 | |
194 | =back |
195 | |
196 | Resets the underlying resultset's cursor, so you can iterate through the |
197 | elements of the column again. |
198 | |
199 | Much like L<DBIx::Class::ResultSet/reset>. |
200 | |
201 | =cut |
202 | |
203 | sub reset { |
204 | my $self = shift; |
205 | $self->_resultset->cursor->reset; |
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206 | return $self; |
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207 | } |
208 | |
209 | =head2 first |
210 | |
211 | =over 4 |
212 | |
213 | =item Arguments: none |
214 | |
215 | =item Return Value: $value |
216 | |
217 | =back |
218 | |
219 | Resets the underlying resultset and returns the next value of the column in the |
220 | resultset (or C<undef> if there is none). |
221 | |
222 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
223 | |
224 | =cut |
225 | |
226 | sub first { |
227 | my $self = shift; |
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228 | |
229 | # using cursor so we don't inflate anything |
230 | $self->_resultset->cursor->reset; |
01dc6781 |
231 | my ($row) = $self->_resultset->cursor->next; |
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232 | |
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233 | return $row; |
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234 | } |
235 | |
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236 | =head2 single |
237 | |
238 | =over 4 |
239 | |
240 | =item Arguments: none |
241 | |
242 | =item Return Value: $value |
243 | |
244 | =back |
245 | |
246 | Much like L<DBIx::Class::ResultSet/single> fetches one and only one column |
247 | value using the cursor directly. If additional rows are present a warning |
248 | is issued before discarding the cursor. |
249 | |
250 | =cut |
251 | |
252 | sub single { |
253 | my $self = shift; |
254 | |
255 | my $attrs = $self->_resultset->_resolved_attrs; |
256 | my ($row) = $self->_resultset->result_source->storage->select_single( |
257 | $attrs->{from}, $attrs->{select}, $attrs->{where}, $attrs |
258 | ); |
259 | |
260 | return $row; |
261 | } |
262 | |
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263 | =head2 min |
264 | |
265 | =over 4 |
266 | |
267 | =item Arguments: none |
268 | |
269 | =item Return Value: $lowest_value |
270 | |
271 | =back |
272 | |
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273 | my $first_year = $year_col->min(); |
274 | |
275 | Wrapper for ->func. Returns the lowest value of the column in the |
276 | resultset (or C<undef> if there are none). |
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277 | |
278 | =cut |
279 | |
280 | sub min { |
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281 | return shift->func('MIN'); |
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282 | } |
283 | |
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284 | =head2 min_rs |
285 | |
286 | =over 4 |
287 | |
288 | =item Arguments: none |
289 | |
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290 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
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291 | |
292 | =back |
293 | |
294 | my $rs = $year_col->min_rs(); |
295 | |
296 | Wrapper for ->func_rs for function MIN(). |
297 | |
298 | =cut |
299 | |
300 | sub min_rs { return shift->func_rs('MIN') } |
301 | |
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302 | =head2 max |
303 | |
304 | =over 4 |
305 | |
306 | =item Arguments: none |
307 | |
308 | =item Return Value: $highest_value |
309 | |
310 | =back |
311 | |
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312 | my $last_year = $year_col->max(); |
313 | |
314 | Wrapper for ->func. Returns the highest value of the column in the |
315 | resultset (or C<undef> if there are none). |
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316 | |
317 | =cut |
318 | |
319 | sub max { |
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320 | return shift->func('MAX'); |
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321 | } |
322 | |
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323 | =head2 max_rs |
324 | |
325 | =over 4 |
326 | |
327 | =item Arguments: none |
328 | |
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329 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
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330 | |
331 | =back |
332 | |
333 | my $rs = $year_col->max_rs(); |
334 | |
335 | Wrapper for ->func_rs for function MAX(). |
336 | |
337 | =cut |
338 | |
339 | sub max_rs { return shift->func_rs('MAX') } |
340 | |
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341 | =head2 sum |
342 | |
343 | =over 4 |
344 | |
345 | =item Arguments: none |
346 | |
347 | =item Return Value: $sum_of_values |
348 | |
349 | =back |
350 | |
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351 | my $total = $prices_col->sum(); |
352 | |
353 | Wrapper for ->func. Returns the sum of all the values in the column of |
354 | the resultset. Use on varchar-like columns at your own risk. |
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355 | |
356 | =cut |
357 | |
358 | sub sum { |
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359 | return shift->func('SUM'); |
2bb7b40b |
360 | } |
361 | |
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362 | =head2 sum_rs |
363 | |
364 | =over 4 |
365 | |
366 | =item Arguments: none |
367 | |
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368 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
4fa7bc22 |
369 | |
370 | =back |
371 | |
372 | my $rs = $year_col->sum_rs(); |
373 | |
374 | Wrapper for ->func_rs for function SUM(). |
375 | |
376 | =cut |
377 | |
378 | sub sum_rs { return shift->func_rs('SUM') } |
379 | |
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380 | =head2 func |
381 | |
382 | =over 4 |
383 | |
384 | =item Arguments: $function |
385 | |
386 | =item Return Value: $function_return_value |
387 | |
388 | =back |
389 | |
e8419341 |
390 | $rs = $schema->resultset("CD")->search({}); |
391 | $length = $rs->get_column('title')->func('LENGTH'); |
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392 | |
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393 | Runs a query using the function on the column and returns the |
394 | value. Produces the following SQL: |
395 | |
396 | SELECT LENGTH( title ) FROM cd me |
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397 | |
398 | =cut |
399 | |
400 | sub func { |
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401 | my ($self,$function) = @_; |
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402 | my $cursor = $self->func_rs($function)->cursor; |
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403 | |
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404 | if( wantarray ) { |
a9da9b6a |
405 | DBIx::Class::_ENV_::ASSERT_NO_INTERNAL_WANTARRAY and my $sog = fail_on_internal_wantarray($self); |
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406 | return map { $_->[ 0 ] } $cursor->all; |
407 | } |
408 | |
409 | return ( $cursor->next )[ 0 ]; |
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410 | } |
411 | |
4fa7bc22 |
412 | =head2 func_rs |
413 | |
414 | =over 4 |
415 | |
416 | =item Arguments: $function |
417 | |
fb13a49f |
418 | =item Return Value: L<$resultset|DBIx::Class::ResultSet> |
4fa7bc22 |
419 | |
420 | =back |
421 | |
422 | Creates the resultset that C<func()> uses to run its query. |
423 | |
424 | =cut |
425 | |
426 | sub func_rs { |
427 | my ($self,$function) = @_; |
3214abc7 |
428 | |
429 | my $rs = $self->{_parent_resultset}; |
430 | my $select = $self->{_select}; |
431 | |
432 | # wrap a grouped rs |
433 | if ($rs->_resolved_attrs->{group_by}) { |
434 | $select = $self->{_as}; |
435 | $rs = $rs->as_subselect_rs; |
436 | } |
437 | |
438 | $rs->search( undef, { |
439 | columns => { $self->{_as} => { $function => $select } } |
440 | } ); |
4fa7bc22 |
441 | } |
442 | |
5d1fc7dc |
443 | =head2 throw_exception |
444 | |
445 | See L<DBIx::Class::Schema/throw_exception> for details. |
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446 | |
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447 | =cut |
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448 | |
5d1fc7dc |
449 | sub throw_exception { |
f9080e45 |
450 | my $self = shift; |
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451 | |
5d1fc7dc |
452 | if (ref $self && $self->{_parent_resultset}) { |
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453 | $self->{_parent_resultset}->throw_exception(@_); |
454 | } |
455 | else { |
456 | DBIx::Class::Exception->throw(@_); |
5d1fc7dc |
457 | } |
458 | } |
459 | |
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460 | # _resultset |
461 | # |
462 | # Arguments: none |
463 | # |
464 | # Return Value: $resultset |
465 | # |
466 | # $year_col->_resultset->next |
467 | # |
468 | # Returns the underlying resultset. Creates it from the parent resultset if |
469 | # necessary. |
b7c79955 |
470 | # |
66521001 |
471 | sub _resultset { |
472 | my $self = shift; |
473 | |
474 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
475 | { |
476 | select => [$self->{_select}], |
477 | as => [$self->{_as}] |
478 | } |
479 | ); |
480 | } |
481 | |
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482 | 1; |
483 | |
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484 | =head1 AUTHOR AND CONTRIBUTORS |
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485 | |
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486 | See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class |
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487 | |
2bb7b40b |
488 | =head1 LICENSE |
489 | |
490 | You may distribute this code under the same terms as Perl itself. |
491 | |
492 | =cut |