Class::DBI keys as accessors

Category:	Database Programming
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Description:	When using Class::DBI with a table such as: `Table: preferences +----+------------------+----------------------------+ \| id \| name \| value \| +----+------------------+----------------------------+ \| 0 \| filename \| /path/to/file.txt \| \| 1 \| item_enabled \| 1 \| \| 2 \| task_name \| something \| +----+------------------+----------------------------+` [download] you want to use: `print DB::Prefs->filename,$/; DB::Prefs->filename("/new/path/to/file");` [download] instead of: `my $row=DB::Prefs->search({ name => "filename" })->first; print $row->value,$/; $row->value("/new/path/to/file");` [download]
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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