README
1NAME
2 Class::DBI::LazyInflate - Defer Inflating Of Columns Until They Are Used
3
4SYNOPSIS
5 package MyData;
6 use base qw(Class::DBI);
7 use Class::DBI::LazyInflate;
8 use DateTime;
9 use DateTime::Format::MySQL;
10
11 __PACKAGE__->has_lazy(
12 'lastmod', 'DateTime',
13 inflate => sub { DateTime::Format::MySQL->parse_datetime(shift) },
14 deflate => sub { DateTime::Format::MySQL->format_datetime(shift) },
15 );
16
17 my $obj = MyData->retrieve($key); # lastmod is not inflated yet
18 $obj->lastmod()->year(); # now it is.
19
20 $obj->lastmod(DateTime->now());
21
22 # Specify another Class::DBI type as a column:
23 __PACKAGE__->has_lazy(cdbi_field => 'MyData');
24
25DESCRIPTION
26 Class::DBI::LazyInflate is a utility class that allows you to create DBI
27 columns that only inflate to an object when it is required. When a row
28 is fetched, columns specified via has_lazy() is wrapped by Data::Lazy,
29 such that it is inflated only when the column is actually used.
30
31 As seen in the SYNOPSIS section, one application of this class is for
32 columns that inflate to objects that are costly to create, such as
33 DateTime. Class::DBI::LazyInflate allows you defer materialization of
34 such objects until when you really need it.
35
36METHODS
37 has_lazy($col, $class, inflate => ..., deflate => ...)
38 has_lazy() declares that column is to be inflated lazily, and is
39 installed to the calling package's namespace upon call to "use
40 Class::DBI::LazyInflate". The arguments are exactly the same as has_a().
41
42 If inflate is not specified, it will lazily perform the default inflate
43 procedure that Class::DBI uses.
44
45AUTHOR
46 Copyright (c) 2004-2005 Daisuke Maki <dmaki@cpan.org>
47
48SEE ALSO
49 Class::DBI Data::Lazy
50
51 For DateTime objects, you may also be interested in DateTime::LazyInit.
52
53