NAME

DBIx::Class::Manual::QuickStart - up and running with DBIC in 10 minutes

DESCRIPTION

This document shows the minimum amount of code to make you a productive DBIC user. It requires you to be familiar with just the basics of database programming (what database tables, rows and columns are) and the basics of Perl object-oriented programming (calling methods on an object instance). It also helps if you already know a bit of SQL and how to connect to a database through DBI.

Follow along with the example database shipping with this distribution, see directory examples/Schema. This database is also used through-out the rest of the documentation.

Preparation

First, install DBIx::Class like you do with any other CPAN distribution. See http://www.cpan.org/modules/INSTALL.html and perlmodinstall.

Then open the distribution in your shell and change to the subdirectory mentioned earlier, the next command will download and unpack it:

$ perl -mCPAN -e'CPAN::Shell->look("DBIx::Class")'
DBIx-Class$ cd examples/Schema

Inspect the database:

DBIx-Class/examples/Schema$ sqlite3 db/example.db .dump

You can also use a GUI database browser such as SQLite Manager.

Have a look at the schema classes files in the subdirectory MyApp. The MyApp::Schema class is the entry point for loading the other classes and interacting with the database through DBIC and the Result classes correspond to the tables in the database. DBIx::Class::Manual::Example shows how to write all that Perl code. That is almost never necessary, though. Instead use dbicdump (part of the distribution DBIx::Class::Schema::Loader) to automatically create schema classes files from an existing database. The chapter "Resetting the database" below shows an example invocation.

Connecting to the database

A schema object represents the database.

use MyApp::Schema qw();
my $schema = MyApp::Schema->connect('dbi:SQLite:db/example.db');

The first four arguments are the same as for "connect" in DBI.

Working with data

Almost all actions go through a resultset object.

Adding data

Via intermediate result objects:

my $artist_ma = $schema->resultset('Artist')->create({
    name => 'Massive Attack',
});
my $cd_mezz = $artist_ma->create_related(cds => {
    title => 'Mezzanine',
});
for ('Angel', 'Teardrop') {
    $cd_mezz->create_related(tracks => {
        title => $_
    });
}

Via relation accessors:

$schema->resultset('Artist')->create({
    name => 'Metallica',
    cds => [
        {
            title => q{Kill 'Em All},
            tracks => [
                { title => 'Jump in the Fire' },
                { title => 'Whiplash' },
            ],
        },
        {
            title => 'ReLoad',
            tracks => [
                { title => 'The Memory Remains' },
                { title => 'The Unforgiven II' },
                { title => 'Fuel' },
            ],
        },
    ],
});

Columns that are not named are filled with default values. The value undef acts as a NULL in the database.

See the chapter "Introspecting the schema classes" below to find out where the non-obvious source name strings such as Artist and accessors such as cds and tracks come from.

Set the environment variable DBI_TRACE='1|SQL' to see the generated queries.

Retrieving data

Set up a condition.

my $artists_starting_with_m = $schema->resultset('Artist')->search(
    {
        name => { like => 'M%' }
    }
);

Iterate over result objects of class MyApp::Schema::Result::Artist. Result objects represent a row and automatically get accessors for their column names.

for my $artist ($artists_starting_with_m->all) {
    say $artist->name;
}

Changing data

Change the release year of all CDs titled ReLoad.

$schema->resultset('Cd')->search(
    {
        title => 'ReLoad',
    }
)->update_all(
    {
        year => 1997,
    }
);

Removing data

Removes all tracks titled Fuel regardless of which CD the belong to.

$schema->resultset('Track')->search(
    {
        title => 'Fuel',
    }
)->delete_all;

Introspecting the schema classes

This is useful for getting a feel for the naming of things in a REPL or during explorative programming.

From the root to the details:

$schema->sources;                       # returns qw(Cd Track Artist)
$schema->source('Cd')->columns;         # returns qw(cdid artist title year)
$schema->source('Cd')->relationships;   # returns qw(artist tracks)

From a detail to the root:

$some_result->result_source;            # returns appropriate source
$some_resultset->result_source;
$some_resultsource->schema;             # returns appropriate schema

Resetting the database

# delete database file
DBIx-Class/examples/Schema$ rm -f db/example.db

# create database and set up tables from definition
DBIx-Class/examples/Schema$ sqlite3 db/example.db < db/example.sql

# fill them with data
DBIx-Class/examples/Schema$ perl ./insertdb.pl

# delete the schema classes files
DBIx-Class/examples/Schema$ rm -rf MyApp

# recreate schema classes files from database file
DBIx-Class/examples/Schema$ dbicdump \
    -o dump_directory=. MyApp::Schema dbi:SQLite:db/example.db

Where to go next

If you want to exercise what you learned with a more complicated schema, load Northwind into your database.

If you want to transfer your existing SQL knowledge, read DBIx::Class::Manual::SQLHackers.

Continue with DBIx::Class::Tutorial and "WHERE TO START READING" in DBIx::Class.

cpanm DBIx::Class

perl -MCPAN -e shell
install DBIx::Class