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