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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 qw(first); |
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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, $column) } |
44 | first { ($attrs->{as} || [])->[$_] eq $column } |
45 | 0..$#{$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 | $self->{_resultset} = $self->{_parent_resultset}->search(undef, {select => [$self->{_select}], as => [$self->{_as}]}) unless ($self->{_resultset}); |
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72 | my ($row) = $self->{_resultset}->cursor->next; |
73 | return $row; |
74 | } |
75 | |
76 | =head2 all |
77 | |
78 | =over 4 |
79 | |
80 | =item Arguments: none |
81 | |
82 | =item Return Value: @values |
83 | |
84 | =back |
85 | |
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86 | Returns all values of the column in the resultset (or C<undef> if |
87 | there are none). |
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88 | |
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89 | Much like L<DBIx::Class::ResultSet/all> but returns values rather |
90 | than row objects. |
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91 | |
92 | =cut |
93 | |
94 | sub all { |
95 | my $self = shift; |
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96 | return map {$_->[0]} $self->{_parent_resultset}->search(undef, {select => [$self->{_select}], as => [$self->{_as}]})->cursor->all; |
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97 | } |
98 | |
99 | =head2 min |
100 | |
101 | =over 4 |
102 | |
103 | =item Arguments: none |
104 | |
105 | =item Return Value: $lowest_value |
106 | |
107 | =back |
108 | |
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109 | my $first_year = $year_col->min(); |
110 | |
111 | Wrapper for ->func. Returns the lowest value of the column in the |
112 | resultset (or C<undef> if there are none). |
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113 | |
114 | =cut |
115 | |
116 | sub min { |
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117 | return shift->func('MIN'); |
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118 | } |
119 | |
120 | =head2 max |
121 | |
122 | =over 4 |
123 | |
124 | =item Arguments: none |
125 | |
126 | =item Return Value: $highest_value |
127 | |
128 | =back |
129 | |
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130 | my $last_year = $year_col->max(); |
131 | |
132 | Wrapper for ->func. Returns the highest value of the column in the |
133 | resultset (or C<undef> if there are none). |
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134 | |
135 | =cut |
136 | |
137 | sub max { |
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138 | return shift->func('MAX'); |
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139 | } |
140 | |
141 | =head2 sum |
142 | |
143 | =over 4 |
144 | |
145 | =item Arguments: none |
146 | |
147 | =item Return Value: $sum_of_values |
148 | |
149 | =back |
150 | |
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151 | my $total = $prices_col->sum(); |
152 | |
153 | Wrapper for ->func. Returns the sum of all the values in the column of |
154 | the resultset. Use on varchar-like columns at your own risk. |
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155 | |
156 | =cut |
157 | |
158 | sub sum { |
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159 | return shift->func('SUM'); |
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160 | } |
161 | |
162 | =head2 func |
163 | |
164 | =over 4 |
165 | |
166 | =item Arguments: $function |
167 | |
168 | =item Return Value: $function_return_value |
169 | |
170 | =back |
171 | |
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172 | $rs = $schema->resultset("CD")->search({}); |
173 | $length = $rs->get_column('title')->func('LENGTH'); |
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174 | |
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175 | Runs a query using the function on the column and returns the |
176 | value. Produces the following SQL: |
177 | |
178 | SELECT LENGTH( title ) FROM cd me |
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179 | |
180 | =cut |
181 | |
182 | sub func { |
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183 | my ($self,$function) = @_; |
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184 | my $cursor = $self->{_parent_resultset}->search(undef, {select => {$function => $self->{_select}}, as => [$self->{_as}]})->cursor; |
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185 | |
186 | if( wantarray ) { |
187 | return map { $_->[ 0 ] } $cursor->all; |
188 | } |
189 | |
190 | return ( $cursor->next )[ 0 ]; |
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191 | } |
192 | |
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193 | =head2 throw_exception |
194 | |
195 | See L<DBIx::Class::Schema/throw_exception> for details. |
196 | |
197 | =cut |
198 | |
199 | sub throw_exception { |
200 | my $self=shift; |
201 | if (ref $self && $self->{_parent_resultset}) { |
202 | $self->{_parent_resultset}->throw_exception(@_) |
203 | } else { |
204 | croak(@_); |
205 | } |
206 | } |
207 | |
208 | |
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209 | 1; |
210 | |
211 | =head1 AUTHORS |
212 | |
213 | Luke Saunders <luke.saunders@gmail.com> |
214 | |
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215 | Jess Robinson |
216 | |
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217 | =head1 LICENSE |
218 | |
219 | You may distribute this code under the same terms as Perl itself. |
220 | |
221 | =cut |