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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 |
42 | my ($select, $as) = |
43 | map { defined $_ ? ($attrs->{select}->[$_], $attrs->{as}->[$_]) : ($column, $column) } |
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44 | List::Util::first { ($attrs->{as} || [])->[$_] eq $column } |
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45 | 0..$#{$attrs->{as} || []}; |
46 | my $new = bless { _select => $select, _as => $as, _parent_resultset => $new_parent_rs }, $class; |
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47 | $new->throw_exception("column must be supplied") unless $column; |
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48 | return $new; |
49 | } |
50 | |
51 | =head2 next |
52 | |
53 | =over 4 |
54 | |
55 | =item Arguments: none |
56 | |
57 | =item Return Value: $value |
58 | |
59 | =back |
60 | |
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61 | Returns the next value of the column in the resultset (or C<undef> if |
62 | there is none). |
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63 | |
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64 | Much like L<DBIx::Class::ResultSet/next> but just returning the |
65 | one value. |
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66 | |
67 | =cut |
68 | |
69 | sub next { |
70 | my $self = shift; |
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71 | my ($row) = $self->_resultset->cursor->next; |
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72 | return $row; |
73 | } |
74 | |
75 | =head2 all |
76 | |
77 | =over 4 |
78 | |
79 | =item Arguments: none |
80 | |
81 | =item Return Value: @values |
82 | |
83 | =back |
84 | |
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85 | Returns all values of the column in the resultset (or C<undef> if |
86 | there are none). |
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87 | |
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88 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
89 | than row objects. |
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90 | |
91 | =cut |
92 | |
93 | sub all { |
94 | my $self = shift; |
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95 | return map { $_->[0] } $self->_resultset->cursor->all; |
96 | } |
97 | |
98 | =head2 reset |
99 | |
100 | =over 4 |
101 | |
102 | =item Arguments: none |
103 | |
104 | =item Return Value: $self |
105 | |
106 | =back |
107 | |
108 | Resets the underlying resultset's cursor, so you can iterate through the |
109 | elements of the column again. |
110 | |
111 | Much like L<DBIx::Class::ResultSet/reset>. |
112 | |
113 | =cut |
114 | |
115 | sub reset { |
116 | my $self = shift; |
117 | $self->_resultset->cursor->reset; |
118 | return $self; |
119 | } |
120 | |
121 | =head2 first |
122 | |
123 | =over 4 |
124 | |
125 | =item Arguments: none |
126 | |
127 | =item Return Value: $value |
128 | |
129 | =back |
130 | |
131 | Resets the underlying resultset and returns the next value of the column in the |
132 | resultset (or C<undef> if there is none). |
133 | |
134 | Much like L<DBIx::Class::ResultSet/first> but just returning the one value. |
135 | |
136 | =cut |
137 | |
138 | sub first { |
139 | my $self = shift; |
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140 | my ($row) = $self->_resultset->cursor->reset->next; |
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141 | return $row; |
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142 | } |
143 | |
144 | =head2 min |
145 | |
146 | =over 4 |
147 | |
148 | =item Arguments: none |
149 | |
150 | =item Return Value: $lowest_value |
151 | |
152 | =back |
153 | |
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154 | my $first_year = $year_col->min(); |
155 | |
156 | Wrapper for ->func. Returns the lowest value of the column in the |
157 | resultset (or C<undef> if there are none). |
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158 | |
159 | =cut |
160 | |
161 | sub min { |
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162 | return shift->func('MIN'); |
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163 | } |
164 | |
165 | =head2 max |
166 | |
167 | =over 4 |
168 | |
169 | =item Arguments: none |
170 | |
171 | =item Return Value: $highest_value |
172 | |
173 | =back |
174 | |
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175 | my $last_year = $year_col->max(); |
176 | |
177 | Wrapper for ->func. Returns the highest value of the column in the |
178 | resultset (or C<undef> if there are none). |
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179 | |
180 | =cut |
181 | |
182 | sub max { |
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183 | return shift->func('MAX'); |
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184 | } |
185 | |
186 | =head2 sum |
187 | |
188 | =over 4 |
189 | |
190 | =item Arguments: none |
191 | |
192 | =item Return Value: $sum_of_values |
193 | |
194 | =back |
195 | |
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196 | my $total = $prices_col->sum(); |
197 | |
198 | Wrapper for ->func. Returns the sum of all the values in the column of |
199 | the resultset. Use on varchar-like columns at your own risk. |
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200 | |
201 | =cut |
202 | |
203 | sub sum { |
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204 | return shift->func('SUM'); |
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205 | } |
206 | |
207 | =head2 func |
208 | |
209 | =over 4 |
210 | |
211 | =item Arguments: $function |
212 | |
213 | =item Return Value: $function_return_value |
214 | |
215 | =back |
216 | |
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217 | $rs = $schema->resultset("CD")->search({}); |
218 | $length = $rs->get_column('title')->func('LENGTH'); |
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219 | |
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220 | Runs a query using the function on the column and returns the |
221 | value. Produces the following SQL: |
222 | |
223 | SELECT LENGTH( title ) FROM cd me |
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224 | |
225 | =cut |
226 | |
227 | sub func { |
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228 | my ($self,$function) = @_; |
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229 | my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor; |
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230 | |
231 | if( wantarray ) { |
232 | return map { $_->[ 0 ] } $cursor->all; |
233 | } |
234 | |
235 | return ( $cursor->next )[ 0 ]; |
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236 | } |
237 | |
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238 | =head2 throw_exception |
239 | |
240 | See L<DBIx::Class::Schema/throw_exception> for details. |
241 | |
242 | =cut |
243 | |
244 | sub throw_exception { |
245 | my $self=shift; |
246 | if (ref $self && $self->{_parent_resultset}) { |
247 | $self->{_parent_resultset}->throw_exception(@_) |
248 | } else { |
249 | croak(@_); |
250 | } |
251 | } |
252 | |
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253 | =head2 _resultset |
254 | |
255 | =over 4 |
256 | |
257 | =item Arguments: none |
258 | |
259 | =item Return Value: $resultset |
260 | |
261 | =back |
262 | |
263 | $year_col->_resultset->next |
264 | |
265 | Returns the underlying resultset. Creates it from the parent resultset if |
266 | necessary. |
267 | |
268 | =cut |
269 | |
270 | sub _resultset { |
271 | my $self = shift; |
272 | |
273 | return $self->{_resultset} ||= $self->{_parent_resultset}->search(undef, |
274 | { |
275 | select => [$self->{_select}], |
276 | as => [$self->{_as}] |
277 | } |
278 | ); |
279 | } |
280 | |
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281 | |
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282 | 1; |
283 | |
284 | =head1 AUTHORS |
285 | |
286 | Luke Saunders <luke.saunders@gmail.com> |
287 | |
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288 | Jess Robinson |
289 | |
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290 | =head1 LICENSE |
291 | |
292 | You may distribute this code under the same terms as Perl itself. |
293 | |
294 | =cut |