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1 | package DBIx::Class::InflateColumn; |
2 | |
3 | use strict; |
4 | use warnings; |
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5 | |
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6 | use base 'DBIx::Class::Row'; |
7 | use DBIx::Class::_Util 'is_literal_value'; |
8 | use namespace::clean; |
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9 | |
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10 | =head1 NAME |
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11 | |
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12 | DBIx::Class::InflateColumn - Automatically create references from column data |
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13 | |
14 | =head1 SYNOPSIS |
15 | |
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16 | # In your table classes |
17 | __PACKAGE__->inflate_column('column_name', { |
18 | inflate => sub { |
19 | my ($raw_value_from_db, $result_object) = @_; |
20 | ... |
21 | }, |
22 | deflate => sub { |
23 | my ($inflated_value_from_user, $result_object) = @_; |
24 | ... |
25 | }, |
26 | }); |
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27 | |
28 | =head1 DESCRIPTION |
29 | |
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30 | This component translates column data into references, i.e. "inflating" |
31 | the column data. It also "deflates" references into an appropriate format |
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32 | for the database. |
33 | |
34 | It can be used, for example, to automatically convert to and from |
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35 | L<DateTime> objects for your date and time fields. There's a |
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36 | convenience component to actually do that though, try |
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37 | L<DBIx::Class::InflateColumn::DateTime>. |
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38 | |
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39 | It will handle all types of references except scalar references. It |
40 | will not handle scalar values, these are ignored and thus passed |
41 | through to L<SQL::Abstract>. This is to allow setting raw values to |
42 | "just work". Scalar references are passed through to the database to |
43 | deal with, to allow such settings as C< \'year + 1'> and C< \'DEFAULT' > |
44 | to work. |
45 | |
46 | If you want to filter plain scalar values and replace them with |
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47 | something else, see L<DBIx::Class::FilterColumn>. |
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48 | |
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49 | =head1 METHODS |
50 | |
51 | =head2 inflate_column |
52 | |
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53 | Instruct L<DBIx::Class> to inflate the given column. |
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54 | |
55 | In addition to the column name, you must provide C<inflate> and |
56 | C<deflate> methods. The C<inflate> method is called when you access |
57 | the field, while the C<deflate> method is called when the field needs |
58 | to used by the database. |
59 | |
60 | For example, if you have a table C<events> with a timestamp field |
61 | named C<insert_time>, you could inflate the column in the |
62 | corresponding table class using something like: |
63 | |
64 | __PACKAGE__->inflate_column('insert_time', { |
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65 | inflate => sub { |
66 | my ($insert_time_raw_value, $event_result_object) = @_; |
67 | DateTime->from_epoch( epoch => $insert_time_raw_value ); |
68 | }, |
69 | deflate => sub { |
70 | my ($insert_time_dt_object, $event_result_object) = @_; |
71 | $insert_time_dt_object->epoch; |
72 | }, |
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73 | }); |
74 | |
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75 | The coderefs you set for inflate and deflate are called with two parameters, |
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76 | the first is the value of the column to be inflated/deflated, the second is |
77 | the result object itself. |
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78 | |
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79 | In this example, calls to an event's C<insert_time> accessor return a |
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80 | L<DateTime> object. This L<DateTime> object is later "deflated" back |
81 | to the integer epoch representation when used in the database layer. |
82 | For a much more thorough handling of the above example, please see |
83 | L<DBIx::Class::DateTime::Epoch> |
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84 | |
85 | =cut |
86 | |
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87 | sub inflate_column { |
88 | my ($self, $col, $attrs) = @_; |
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89 | |
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90 | my $colinfo = $self->column_info($col); |
91 | |
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92 | $self->throw_exception("InflateColumn does not work with FilterColumn") |
93 | if $self->isa('DBIx::Class::FilterColumn') && |
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94 | defined $colinfo->{_filter_info}; |
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95 | |
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96 | $self->throw_exception("No such column $col to inflate") |
97 | unless $self->has_column($col); |
98 | $self->throw_exception("inflate_column needs attr hashref") |
99 | unless ref $attrs eq 'HASH'; |
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100 | $colinfo->{_inflate_info} = $attrs; |
101 | my $acc = $colinfo->{accessor}; |
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102 | $self->mk_group_accessors('inflated_column' => [ (defined $acc ? $acc : $col), $col]); |
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103 | return 1; |
104 | } |
105 | |
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106 | sub _inflated_column { |
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107 | my ($self, $col, $value) = @_; |
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108 | return $value unless defined $value; # NULL is NULL is NULL |
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109 | |
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110 | my $info = $self->column_info($col) |
111 | or $self->throw_exception("No column info for $col"); |
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112 | |
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113 | return $value unless exists $info->{_inflate_info}; |
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114 | |
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115 | my $inflate = $info->{_inflate_info}{inflate}; |
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116 | $self->throw_exception("No inflator for $col") unless defined $inflate; |
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117 | |
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118 | return $inflate->($value, $self); |
119 | } |
120 | |
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121 | sub _deflated_column { |
122 | my ($self, $col, $value) = @_; |
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123 | |
124 | ## Deflate any refs except for literals, pass through plain values |
125 | return $value if ( |
126 | ! length ref $value |
127 | or |
128 | is_literal_value($value) |
129 | ); |
130 | |
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131 | my $info = $self->column_info($col) or |
132 | $self->throw_exception("No column info for $col"); |
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133 | |
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134 | return $value unless exists $info->{_inflate_info}; |
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135 | |
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136 | my $deflate = $info->{_inflate_info}{deflate}; |
137 | $self->throw_exception("No deflator for $col") unless defined $deflate; |
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138 | |
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139 | return $deflate->($value, $self); |
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140 | } |
141 | |
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142 | =head2 get_inflated_column |
143 | |
144 | my $val = $obj->get_inflated_column($col); |
145 | |
146 | Fetch a column value in its inflated state. This is directly |
147 | analogous to L<DBIx::Class::Row/get_column> in that it only fetches a |
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148 | column already retrieved from the database, and then inflates it. |
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149 | Throws an exception if the column requested is not an inflated column. |
150 | |
151 | =cut |
152 | |
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153 | sub get_inflated_column { |
154 | my ($self, $col) = @_; |
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155 | $self->throw_exception("$col is not an inflated column") |
156 | unless exists $self->column_info($col)->{_inflate_info}; |
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157 | return $self->{_inflated_column}{$col} |
158 | if exists $self->{_inflated_column}{$col}; |
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159 | |
160 | my $val = $self->get_column($col); |
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161 | |
162 | return $val if is_literal_value($val); #that would be a not-yet-reloaded literal update |
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163 | |
164 | return $self->{_inflated_column}{$col} = $self->_inflated_column($col, $val); |
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165 | } |
166 | |
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167 | =head2 set_inflated_column |
168 | |
169 | my $copy = $obj->set_inflated_column($col => $val); |
170 | |
171 | Sets a column value from an inflated value. This is directly |
172 | analogous to L<DBIx::Class::Row/set_column>. |
173 | |
174 | =cut |
175 | |
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176 | sub set_inflated_column { |
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177 | my ($self, $col, $inflated) = @_; |
178 | $self->set_column($col, $self->_deflated_column($col, $inflated)); |
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179 | |
180 | if (length ref $inflated and ! is_literal_value($inflated) ) { |
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181 | $self->{_inflated_column}{$col} = $inflated; |
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182 | } else { |
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183 | delete $self->{_inflated_column}{$col}; |
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184 | } |
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185 | return $inflated; |
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186 | } |
187 | |
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188 | =head2 store_inflated_column |
189 | |
190 | my $copy = $obj->store_inflated_column($col => $val); |
191 | |
192 | Sets a column value from an inflated value without marking the column |
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193 | as dirty. This is directly analogous to L<DBIx::Class::Row/store_column>. |
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194 | |
195 | =cut |
196 | |
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197 | sub store_inflated_column { |
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198 | my ($self, $col, $inflated) = @_; |
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199 | |
200 | if (is_literal_value($inflated)) { |
201 | delete $self->{_inflated_column}{$col}; |
202 | $self->store_column($col => $inflated); |
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203 | } |
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204 | else { |
205 | delete $self->{_column_data}{$col}; |
206 | $self->{_inflated_column}{$col} = $inflated; |
207 | } |
208 | |
209 | return $inflated; |
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210 | } |
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211 | |
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212 | =head1 SEE ALSO |
213 | |
214 | =over 4 |
215 | |
216 | =item L<DBIx::Class::Core> - This component is loaded as part of the |
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217 | C<core> L<DBIx::Class> components; generally there is no need to |
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218 | load it directly |
219 | |
220 | =back |
221 | |
222 | =head1 AUTHOR |
223 | |
224 | Matt S. Trout <mst@shadowcatsystems.co.uk> |
225 | |
226 | =head1 CONTRIBUTORS |
227 | |
228 | Daniel Westermann-Clark <danieltwc@cpan.org> (documentation) |
229 | |
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230 | Jess Robinson <cpan@desert-island.demon.co.uk> |
231 | |
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232 | =head1 LICENSE |
233 | |
234 | You may distribute this code under the same terms as Perl itself. |
235 | |
236 | =cut |
237 | |
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238 | 1; |