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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 can not be used on a column with a declared FilterColumn filter") |
93 | if defined $colinfo->{_filter_info} and $self->isa('DBIx::Class::FilterColumn'); |
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94 | |
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95 | $self->throw_exception("No such column $col to inflate") |
96 | unless $self->has_column($col); |
97 | $self->throw_exception("inflate_column needs attr hashref") |
98 | unless ref $attrs eq 'HASH'; |
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99 | $colinfo->{_inflate_info} = $attrs; |
100 | my $acc = $colinfo->{accessor}; |
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101 | $self->mk_group_accessors('inflated_column' => [ (defined $acc ? $acc : $col), $col]); |
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102 | return 1; |
103 | } |
104 | |
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105 | sub _inflated_column { |
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106 | my ($self, $col, $value) = @_; |
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107 | return $value unless defined $value; # NULL is NULL is NULL |
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108 | |
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109 | my $info = $self->column_info($col) |
110 | or $self->throw_exception("No column info for $col"); |
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111 | |
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112 | return $value unless exists $info->{_inflate_info}; |
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113 | |
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114 | my $inflate = $info->{_inflate_info}{inflate}; |
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115 | $self->throw_exception("No inflator for $col") unless defined $inflate; |
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116 | |
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117 | return $inflate->($value, $self); |
118 | } |
119 | |
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120 | sub _deflated_column { |
121 | my ($self, $col, $value) = @_; |
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122 | |
123 | ## Deflate any refs except for literals, pass through plain values |
124 | return $value if ( |
125 | ! length ref $value |
126 | or |
127 | is_literal_value($value) |
128 | ); |
129 | |
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130 | my $info = $self->column_info($col) or |
131 | $self->throw_exception("No column info for $col"); |
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132 | |
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133 | return $value unless exists $info->{_inflate_info}; |
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134 | |
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135 | my $deflate = $info->{_inflate_info}{deflate}; |
136 | $self->throw_exception("No deflator for $col") unless defined $deflate; |
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137 | |
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138 | return $deflate->($value, $self); |
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139 | } |
140 | |
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141 | =head2 get_inflated_column |
142 | |
143 | my $val = $obj->get_inflated_column($col); |
144 | |
145 | Fetch a column value in its inflated state. This is directly |
146 | analogous to L<DBIx::Class::Row/get_column> in that it only fetches a |
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147 | column already retrieved from the database, and then inflates it. |
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148 | Throws an exception if the column requested is not an inflated column. |
149 | |
150 | =cut |
151 | |
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152 | sub get_inflated_column { |
153 | my ($self, $col) = @_; |
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154 | $self->throw_exception("$col is not an inflated column") |
155 | unless exists $self->column_info($col)->{_inflate_info}; |
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156 | return $self->{_inflated_column}{$col} |
157 | if exists $self->{_inflated_column}{$col}; |
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158 | |
159 | my $val = $self->get_column($col); |
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160 | |
161 | return $val if is_literal_value($val); #that would be a not-yet-reloaded literal update |
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162 | |
163 | return $self->{_inflated_column}{$col} = $self->_inflated_column($col, $val); |
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164 | } |
165 | |
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166 | =head2 set_inflated_column |
167 | |
168 | my $copy = $obj->set_inflated_column($col => $val); |
169 | |
170 | Sets a column value from an inflated value. This is directly |
171 | analogous to L<DBIx::Class::Row/set_column>. |
172 | |
173 | =cut |
174 | |
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175 | sub set_inflated_column { |
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176 | my ($self, $col, $inflated) = @_; |
177 | $self->set_column($col, $self->_deflated_column($col, $inflated)); |
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178 | |
179 | if (length ref $inflated and ! is_literal_value($inflated) ) { |
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180 | $self->{_inflated_column}{$col} = $inflated; |
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181 | } else { |
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182 | delete $self->{_inflated_column}{$col}; |
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183 | } |
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184 | return $inflated; |
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185 | } |
186 | |
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187 | =head2 store_inflated_column |
188 | |
189 | my $copy = $obj->store_inflated_column($col => $val); |
190 | |
191 | Sets a column value from an inflated value without marking the column |
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192 | as dirty. This is directly analogous to L<DBIx::Class::Row/store_column>. |
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193 | |
194 | =cut |
195 | |
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196 | sub store_inflated_column { |
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197 | my ($self, $col, $inflated) = @_; |
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198 | |
199 | if (is_literal_value($inflated)) { |
200 | delete $self->{_inflated_column}{$col}; |
201 | $self->store_column($col => $inflated); |
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202 | } |
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203 | else { |
204 | delete $self->{_column_data}{$col}; |
205 | $self->{_inflated_column}{$col} = $inflated; |
206 | } |
207 | |
208 | return $inflated; |
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209 | } |
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210 | |
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211 | =head1 SEE ALSO |
212 | |
213 | =over 4 |
214 | |
215 | =item L<DBIx::Class::Core> - This component is loaded as part of the |
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216 | C<core> L<DBIx::Class> components; generally there is no need to |
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217 | load it directly |
218 | |
219 | =back |
220 | |
221 | =head1 AUTHOR |
222 | |
223 | Matt S. Trout <mst@shadowcatsystems.co.uk> |
224 | |
225 | =head1 CONTRIBUTORS |
226 | |
227 | Daniel Westermann-Clark <danieltwc@cpan.org> (documentation) |
228 | |
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229 | Jess Robinson <cpan@desert-island.demon.co.uk> |
230 | |
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231 | =head1 LICENSE |
232 | |
233 | You may distribute this code under the same terms as Perl itself. |
234 | |
235 | =cut |
236 | |
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237 | 1; |