Category: | Database Programming |
Author/Contact Info | |
Description: | When using Class::DBI with a table such as:
you want to use: instead of:
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Say you want to store configuration data in a database, such as:
Table: preferences +----+------------------+----------------------------+ | id | name | value | +----+------------------+----------------------------+ | 0 | filename | /path/to/file.txt | | 1 | item_enabled | 1 | | 2 | task_name | something | +----+------------------+----------------------------+but instead of doing: my $row=DB::Prefs->search({ name => "filename" })->first; print $row->value,$/; $row->value("/new/path/to/file");you want to set up accessors to point to the row in the database rather than the column: print DB::Prefs->filename,$/; DB::Prefs->filename("/new/path/to/file");which is much easier to use and looks cleaner. All you have to do is create your Prefs class with an AUTOLOAD function, as below: package App::Prefs; use base 'App'; use strict; __PACKAGE__->table("preferences"); __PACKAGE__->columns( ALL => qw/ id name value/ ); sub AUTOLOAD { my $self = shift; my $newval = shift; my $attr = our $AUTOLOAD; $attr =~ s/.*:://; return if($attr eq "DESTROY"); my $row = $self->search({ name => "$attr" })->first(); if(defined($newval)) { if(!$row) { $row=$self->insert({ name => "$attr" }); } $row->value($newval); $row->update(); } return defined($row) ? $row->value : undef; }So calling an accessor with no matching "name" in the preferences table will return "undef", calling an accessor with a parameter will insert that name/value pair into the table, and thereafter calling the accessor will return the correct value for the name matching the accessor |
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