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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 | my $new_parent_rs = $rs->search_rs; # we don't want to mess up the original, so clone it |
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40 | my $attrs = $new_parent_rs->_resolved_attrs; |
41 | $new_parent_rs->{attrs}->{$_} = undef for qw(prefetch include_columns +select +as); # prefetch, include_columns, +select, +as cause additional columns to be fetched |
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42 | |
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43 | # If $column can be found in the 'as' list of the parent resultset, use the |
44 | # corresponding element of its 'select' list (to keep any custom column |
45 | # definition set up with 'select' or '+select' attrs), otherwise use $column |
46 | # (to create a new column definition on-the-fly). |
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47 | my $as_list = $attrs->{as} || []; |
48 | my $select_list = $attrs->{select} || []; |
49 | my $as_index = List::Util::first { ($as_list->[$_] || "") eq $column } 0..$#$as_list; |
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50 | my $select = defined $as_index ? $select_list->[$as_index] : $column; |
51 | |
52 | my $new = bless { _select => $select, _as => $column, _parent_resultset => $new_parent_rs }, $class; |
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53 | $new->throw_exception("column must be supplied") unless $column; |
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54 | return $new; |
55 | } |
56 | |
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57 | =head2 as_query |
58 | |
59 | =over 4 |
60 | |
61 | =item Arguments: none |
62 | |
63 | =item Return Value: [ $sql, @bind ] |
64 | |
65 | =back |
66 | |
67 | Returns the SQL query and bind vars associated with the invocant. |
68 | |
69 | =cut |
70 | |
71 | sub as_query { return shift->_resultset->as_query } |
72 | |
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73 | =head2 next |
74 | |
75 | =over 4 |
76 | |
77 | =item Arguments: none |
78 | |
79 | =item Return Value: $value |
80 | |
81 | =back |
82 | |
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83 | Returns the next value of the column in the resultset (or C<undef> if |
84 | there is none). |
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85 | |
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86 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
87 | one value. |
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88 | |
89 | =cut |
90 | |
91 | sub next { |
92 | my $self = shift; |
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93 | my ($row) = $self->_resultset->cursor->next; |
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94 | return $row; |
95 | } |
96 | |
97 | =head2 all |
98 | |
99 | =over 4 |
100 | |
101 | =item Arguments: none |
102 | |
103 | =item Return Value: @values |
104 | |
105 | =back |
106 | |
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107 | Returns all values of the column in the resultset (or C<undef> if |
108 | there are none). |
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109 | |
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110 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
111 | than row objects. |
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112 | |
113 | =cut |
114 | |
115 | sub all { |
116 | my $self = shift; |
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117 | return map { $_->[0] } $self->_resultset->cursor->all; |
118 | } |
119 | |
120 | =head2 reset |
121 | |
122 | =over 4 |
123 | |
124 | =item Arguments: none |
125 | |
126 | =item Return Value: $self |
127 | |
128 | =back |
129 | |
130 | Resets the underlying resultset's cursor, so you can iterate through the |
131 | elements of the column again. |
132 | |
133 | Much like L<DBIx::Class::ResultSet/reset>. |
134 | |
135 | =cut |
136 | |
137 | sub reset { |
138 | my $self = shift; |
139 | $self->_resultset->cursor->reset; |
140 | return $self; |
141 | } |
142 | |
143 | =head2 first |
144 | |
145 | =over 4 |
146 | |
147 | =item Arguments: none |
148 | |
149 | =item Return Value: $value |
150 | |
151 | =back |
152 | |
153 | Resets the underlying resultset and returns the next value of the column in the |
154 | resultset (or C<undef> if there is none). |
155 | |
156 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
157 | |
158 | =cut |
159 | |
160 | sub first { |
161 | my $self = shift; |
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162 | my ($row) = $self->_resultset->cursor->reset->next; |
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163 | return $row; |
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164 | } |
165 | |
166 | =head2 min |
167 | |
168 | =over 4 |
169 | |
170 | =item Arguments: none |
171 | |
172 | =item Return Value: $lowest_value |
173 | |
174 | =back |
175 | |
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176 | my $first_year = $year_col->min(); |
177 | |
178 | Wrapper for ->func. Returns the lowest value of the column in the |
179 | resultset (or C<undef> if there are none). |
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180 | |
181 | =cut |
182 | |
183 | sub min { |
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184 | return shift->func('MIN'); |
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185 | } |
186 | |
187 | =head2 max |
188 | |
189 | =over 4 |
190 | |
191 | =item Arguments: none |
192 | |
193 | =item Return Value: $highest_value |
194 | |
195 | =back |
196 | |
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197 | my $last_year = $year_col->max(); |
198 | |
199 | Wrapper for ->func. Returns the highest value of the column in the |
200 | resultset (or C<undef> if there are none). |
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201 | |
202 | =cut |
203 | |
204 | sub max { |
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205 | return shift->func('MAX'); |
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206 | } |
207 | |
208 | =head2 sum |
209 | |
210 | =over 4 |
211 | |
212 | =item Arguments: none |
213 | |
214 | =item Return Value: $sum_of_values |
215 | |
216 | =back |
217 | |
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218 | my $total = $prices_col->sum(); |
219 | |
220 | Wrapper for ->func. Returns the sum of all the values in the column of |
221 | the resultset. Use on varchar-like columns at your own risk. |
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222 | |
223 | =cut |
224 | |
225 | sub sum { |
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226 | return shift->func('SUM'); |
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227 | } |
228 | |
229 | =head2 func |
230 | |
231 | =over 4 |
232 | |
233 | =item Arguments: $function |
234 | |
235 | =item Return Value: $function_return_value |
236 | |
237 | =back |
238 | |
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239 | $rs = $schema->resultset("CD")->search({}); |
240 | $length = $rs->get_column('title')->func('LENGTH'); |
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241 | |
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242 | Runs a query using the function on the column and returns the |
243 | value. Produces the following SQL: |
244 | |
245 | SELECT LENGTH( title ) FROM cd me |
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246 | |
247 | =cut |
248 | |
249 | sub func { |
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250 | my ($self,$function) = @_; |
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251 | my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor; |
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252 | |
253 | if( wantarray ) { |
254 | return map { $_->[ 0 ] } $cursor->all; |
255 | } |
256 | |
257 | return ( $cursor->next )[ 0 ]; |
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258 | } |
259 | |
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260 | =head2 throw_exception |
261 | |
262 | See L<DBIx::Class::Schema/throw_exception> for details. |
263 | |
264 | =cut |
265 | |
266 | sub throw_exception { |
267 | my $self=shift; |
268 | if (ref $self && $self->{_parent_resultset}) { |
269 | $self->{_parent_resultset}->throw_exception(@_) |
270 | } else { |
271 | croak(@_); |
272 | } |
273 | } |
274 | |
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275 | # _resultset |
276 | # |
277 | # Arguments: none |
278 | # |
279 | # Return Value: $resultset |
280 | # |
281 | # $year_col->_resultset->next |
282 | # |
283 | # Returns the underlying resultset. Creates it from the parent resultset if |
284 | # necessary. |
285 | # |
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286 | sub _resultset { |
287 | my $self = shift; |
288 | |
289 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
290 | { |
291 | select => [$self->{_select}], |
292 | as => [$self->{_as}] |
293 | } |
294 | ); |
295 | } |
296 | |
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297 | 1; |
298 | |
299 | =head1 AUTHORS |
300 | |
301 | Luke Saunders <luke.saunders@gmail.com> |
302 | |
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303 | Jess Robinson |
304 | |
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305 | =head1 LICENSE |
306 | |
307 | You may distribute this code under the same terms as Perl itself. |
308 | |
309 | =cut |