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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 $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it |
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43 | |
44 | # prefetch causes additional columns to be fetched, but we can not just make a new |
45 | # rs via the _resolved_attrs trick - we need to retain the separation between |
bed3a173 |
46 | # +select/+as and select/as. At the same time we want to preserve any joins that the |
47 | # prefetch would otherwise generate. |
48 | my $init_attrs = $new_parent_rs->{attrs} ||= {}; |
49 | delete $init_attrs->{collapse}; |
50 | $init_attrs->{join} = $rs->_merge_attr( delete $init_attrs->{join}, delete $init_attrs->{prefetch} ); |
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51 | |
152002c4 |
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). |
7ae9706c |
56 | my $attrs = $new_parent_rs->_resolved_attrs; |
57 | |
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58 | my $as_list = $attrs->{as} || []; |
59 | my $select_list = $attrs->{select} || []; |
60 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
b6e85b48 |
61 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
62 | |
63 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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64 | return $new; |
65 | } |
66 | |
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67 | =head2 as_query (EXPERIMENTAL) |
658fa250 |
68 | |
69 | =over 4 |
70 | |
428a645e |
71 | =item Arguments: none |
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72 | |
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73 | =item Return Value: \[ $sql, @bind ] |
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74 | |
75 | =back |
76 | |
77 | Returns the SQL query and bind vars associated with the invocant. |
78 | |
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79 | This is generally used as the RHS for a subquery. |
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80 | |
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81 | B<NOTE>: This feature is still experimental. |
82 | |
c7a9d102 |
83 | =cut |
84 | |
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85 | sub as_query { return shift->_resultset->as_query(@_) } |
c7a9d102 |
86 | |
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87 | =head2 next |
88 | |
89 | =over 4 |
90 | |
91 | =item Arguments: none |
92 | |
93 | =item Return Value: $value |
94 | |
95 | =back |
96 | |
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97 | Returns the next value of the column in the resultset (or C<undef> if |
98 | there is none). |
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99 | |
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100 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
101 | one value. |
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102 | |
103 | =cut |
104 | |
105 | sub next { |
106 | my $self = shift; |
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107 | my ($row) = $self->_resultset->cursor->next; |
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108 | return $row; |
109 | } |
110 | |
111 | =head2 all |
112 | |
113 | =over 4 |
114 | |
115 | =item Arguments: none |
116 | |
117 | =item Return Value: @values |
118 | |
119 | =back |
120 | |
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121 | Returns all values of the column in the resultset (or C<undef> if |
122 | there are none). |
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123 | |
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124 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
125 | than row objects. |
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126 | |
127 | =cut |
128 | |
129 | sub all { |
130 | my $self = shift; |
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131 | return map { $_->[0] } $self->_resultset->cursor->all; |
132 | } |
133 | |
134 | =head2 reset |
135 | |
136 | =over 4 |
137 | |
138 | =item Arguments: none |
139 | |
140 | =item Return Value: $self |
141 | |
142 | =back |
143 | |
144 | Resets the underlying resultset's cursor, so you can iterate through the |
145 | elements of the column again. |
146 | |
147 | Much like L<DBIx::Class::ResultSet/reset>. |
148 | |
149 | =cut |
150 | |
151 | sub reset { |
152 | my $self = shift; |
153 | $self->_resultset->cursor->reset; |
154 | return $self; |
155 | } |
156 | |
157 | =head2 first |
158 | |
159 | =over 4 |
160 | |
161 | =item Arguments: none |
162 | |
163 | =item Return Value: $value |
164 | |
165 | =back |
166 | |
167 | Resets the underlying resultset and returns the next value of the column in the |
168 | resultset (or C<undef> if there is none). |
169 | |
170 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
171 | |
172 | =cut |
173 | |
174 | sub first { |
175 | my $self = shift; |
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176 | my ($row) = $self->_resultset->cursor->reset->next; |
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177 | return $row; |
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178 | } |
179 | |
180 | =head2 min |
181 | |
182 | =over 4 |
183 | |
184 | =item Arguments: none |
185 | |
186 | =item Return Value: $lowest_value |
187 | |
188 | =back |
189 | |
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190 | my $first_year = $year_col->min(); |
191 | |
192 | Wrapper for ->func. Returns the lowest value of the column in the |
193 | resultset (or C<undef> if there are none). |
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194 | |
195 | =cut |
196 | |
197 | sub min { |
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198 | return shift->func('MIN'); |
2bb7b40b |
199 | } |
200 | |
4fa7bc22 |
201 | =head2 min_rs |
202 | |
203 | =over 4 |
204 | |
205 | =item Arguments: none |
206 | |
207 | =item Return Value: $resultset |
208 | |
209 | =back |
210 | |
211 | my $rs = $year_col->min_rs(); |
212 | |
213 | Wrapper for ->func_rs for function MIN(). |
214 | |
215 | =cut |
216 | |
217 | sub min_rs { return shift->func_rs('MIN') } |
218 | |
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219 | =head2 max |
220 | |
221 | =over 4 |
222 | |
223 | =item Arguments: none |
224 | |
225 | =item Return Value: $highest_value |
226 | |
227 | =back |
228 | |
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229 | my $last_year = $year_col->max(); |
230 | |
231 | Wrapper for ->func. Returns the highest value of the column in the |
232 | resultset (or C<undef> if there are none). |
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233 | |
234 | =cut |
235 | |
236 | sub max { |
6b051e14 |
237 | return shift->func('MAX'); |
2bb7b40b |
238 | } |
239 | |
4fa7bc22 |
240 | =head2 max_rs |
241 | |
242 | =over 4 |
243 | |
244 | =item Arguments: none |
245 | |
246 | =item Return Value: $resultset |
247 | |
248 | =back |
249 | |
250 | my $rs = $year_col->max_rs(); |
251 | |
252 | Wrapper for ->func_rs for function MAX(). |
253 | |
254 | =cut |
255 | |
256 | sub max_rs { return shift->func_rs('MAX') } |
257 | |
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258 | =head2 sum |
259 | |
260 | =over 4 |
261 | |
262 | =item Arguments: none |
263 | |
264 | =item Return Value: $sum_of_values |
265 | |
266 | =back |
267 | |
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268 | my $total = $prices_col->sum(); |
269 | |
270 | Wrapper for ->func. Returns the sum of all the values in the column of |
271 | the resultset. Use on varchar-like columns at your own risk. |
2bb7b40b |
272 | |
273 | =cut |
274 | |
275 | sub sum { |
6b051e14 |
276 | return shift->func('SUM'); |
2bb7b40b |
277 | } |
278 | |
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279 | =head2 sum_rs |
280 | |
281 | =over 4 |
282 | |
283 | =item Arguments: none |
284 | |
285 | =item Return Value: $resultset |
286 | |
287 | =back |
288 | |
289 | my $rs = $year_col->sum_rs(); |
290 | |
291 | Wrapper for ->func_rs for function SUM(). |
292 | |
293 | =cut |
294 | |
295 | sub sum_rs { return shift->func_rs('SUM') } |
296 | |
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297 | =head2 func |
298 | |
299 | =over 4 |
300 | |
301 | =item Arguments: $function |
302 | |
303 | =item Return Value: $function_return_value |
304 | |
305 | =back |
306 | |
e8419341 |
307 | $rs = $schema->resultset("CD")->search({}); |
308 | $length = $rs->get_column('title')->func('LENGTH'); |
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309 | |
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310 | Runs a query using the function on the column and returns the |
311 | value. Produces the following SQL: |
312 | |
313 | SELECT LENGTH( title ) FROM cd me |
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314 | |
315 | =cut |
316 | |
317 | sub func { |
6b051e14 |
318 | my ($self,$function) = @_; |
4fa7bc22 |
319 | my $cursor = $self->func_rs($function)->cursor; |
5d62876f |
320 | |
321 | if( wantarray ) { |
322 | return map { $_->[ 0 ] } $cursor->all; |
323 | } |
324 | |
325 | return ( $cursor->next )[ 0 ]; |
2bb7b40b |
326 | } |
327 | |
4fa7bc22 |
328 | =head2 func_rs |
329 | |
330 | =over 4 |
331 | |
332 | =item Arguments: $function |
333 | |
334 | =item Return Value: $resultset |
335 | |
336 | =back |
337 | |
338 | Creates the resultset that C<func()> uses to run its query. |
339 | |
340 | =cut |
341 | |
342 | sub func_rs { |
343 | my ($self,$function) = @_; |
344 | return $self->{_parent_resultset}->search( |
345 | undef, { |
346 | select => {$function => $self->{_select}}, |
347 | as => [$self->{_as}], |
348 | }, |
349 | ); |
350 | } |
351 | |
5d1fc7dc |
352 | =head2 throw_exception |
353 | |
354 | See L<DBIx::Class::Schema/throw_exception> for details. |
355 | |
356 | =cut |
357 | |
358 | sub throw_exception { |
359 | my $self=shift; |
360 | if (ref $self && $self->{_parent_resultset}) { |
361 | $self->{_parent_resultset}->throw_exception(@_) |
362 | } else { |
363 | croak(@_); |
364 | } |
365 | } |
366 | |
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367 | # _resultset |
368 | # |
369 | # Arguments: none |
370 | # |
371 | # Return Value: $resultset |
372 | # |
373 | # $year_col->_resultset->next |
374 | # |
375 | # Returns the underlying resultset. Creates it from the parent resultset if |
376 | # necessary. |
377 | # |
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378 | sub _resultset { |
379 | my $self = shift; |
380 | |
381 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
382 | { |
383 | select => [$self->{_select}], |
384 | as => [$self->{_as}] |
385 | } |
386 | ); |
387 | } |
388 | |
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389 | 1; |
390 | |
391 | =head1 AUTHORS |
392 | |
393 | Luke Saunders <luke.saunders@gmail.com> |
394 | |
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395 | Jess Robinson |
396 | |
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397 | =head1 LICENSE |
398 | |
399 | You may distribute this code under the same terms as Perl itself. |
400 | |
401 | =cut |