NAME
Mojo::SQLite - A tiny Mojolicious wrapper for SQLite
SYNOPSIS
use Mojo::SQLite;
# Select the library version
my $sql = Mojo::SQLite->new('sqlite:test.db');
say $sql->db->query('select sqlite_version() as version')->hash->{version};
# Use migrations to create a table
$sql->migrations->name('my_names_app')->from_string(<<EOF)->migrate;
-- 1 up
create table names (id integer primary key autoincrement, name text);
-- 1 down
drop table names;
EOF
# Use migrations to drop and recreate the table
$sql->migrations->migrate(0)->migrate;
# Insert a few rows
my $db = $sql->db;
$db->query('insert into names (name) values (?)', 'Sara');
$db->query('insert into names (name) values (?)', 'Stefan');
# Insert more rows in a transaction
eval {
my $tx = $db->begin;
$db->query('insert into names (name) values (?)', 'Baerbel');
$db->query('insert into names (name) values (?)', 'Wolfgang');
$tx->commit;
};
say $@ if $@;
# Insert another row and return the generated id
say $db->query('insert into names (name) values (?)', 'Daniel')
->last_insert_id;
# JSON roundtrip
say $db->query('select ? as foo', {json => {bar => 'baz'}})
->expand(json => 'foo')->hash->{foo}{bar};
# Select one row at a time
my $results = $db->query('select * from names');
while (my $next = $results->hash) {
say $next->{name};
}
# Select all rows
say $_->{name} for $db->query('select * from names')->hashes->each;
# Send and receive notifications non-blocking
$sql->pubsub->listen(foo => sub {
my ($pubsub, $payload) = @_;
say "foo: $payload";
$pubsub->notify(bar => $payload);
});
$sql->pubsub->listen(bar => sub {
my ($pubsub, $payload) = @_;
say "bar: $payload";
});
$sql->pubsub->notify(foo => 'SQLite rocks!');
Mojo::IOLoop->start unless Mojo::IOLoop->is_running;DESCRIPTION
Mojo::SQLite is a tiny wrapper around DBD::SQLite that makes SQLite a lot of fun to use with the Mojolicious real-time web framework.
Database and statement handles are cached automatically, so they can be reused transparently to increase performance. And you can handle connection timeouts gracefully by holding on to them only for short amounts of time.
use Mojolicious::Lite;
use Mojo::SQLite;
helper sqlite => sub { state $sql = Mojo::SQLite->new('sqlite:test.db') };
get '/' => sub {
my $c = shift;
my $db = $c->sqlite->db;
$c->render(json => $db->query('select datetime("now","localtime") as now')->hash);
};
app->start;In this example application, we create a sqlite helper to store a Mojo::SQLite object. Our action calls that helper and uses the method "db" in Mojo::SQLite to dequeue a Mojo::SQLite::Database object from the connection pool. Then we use the method "query" in Mojo::SQLite::Database to execute an SQL statement, which returns a Mojo::SQLite::Results object. And finally we call the method "hash" in Mojo::SQLite::Results to retrieve the first row as a hash reference.
All I/O and queries are performed synchronously. However, the "Write-Ahead Log" journal is enabled for all connections, allowing multiple processes to read and write concurrently to the same database file (but only one can write at a time). See http://sqlite.org/wal.html for more information.
# Performed concurrently
my $pid = fork || die $!;
say $sql->db->query('select datetime("now","localtime") as time')->hash->{time};
exit unless $pid;All cached database handles will be reset automatically if a new process has been forked, this allows multiple processes to share the same Mojo::SQLite object safely.
Any database errors will throw an exception as RaiseError is automatically enabled, so use eval or Try::Tiny to catch them. This makes transactions with "begin" in Mojo::SQLite::Database easy.
While passing a file path of :memory: (or a custom "dsn" with mode=memory) will create a temporary database, in-memory databases cannot be shared between connections, so subsequent calls to "db" may return connections to completely different databases. For a temporary database that can be shared between connections and processes, pass a file path of :temp: to store the database in a temporary directory (this is the default), or consider constructing a temporary directory yourself with File::Temp if you need to reuse the filename. A temporary directory allows SQLite to create additional temporary files safely.
use File::Spec::Functions 'catfile';
use File::Temp;
use Mojo::SQLite;
my $tempdir = File::Temp->newdir; # Deleted when object goes out of scope
my $tempfile = catfile $tempdir, 'test.db';
my $sql = Mojo::SQLite->new->from_filename($tempfile);EVENTS
Mojo::SQLite inherits all events from Mojo::EventEmitter and can emit the following new ones.
connection
$sql->on(connection => sub {
my ($sql, $dbh) = @_;
$dbh->do('pragma journal_size_limit=1000000');
});Emitted when a new database connection has been established.
ATTRIBUTES
Mojo::SQLite implements the following attributes.
auto_migrate
my $bool = $sql->auto_migrate;
$sql = $sql->auto_migrate($bool);Automatically migrate to the latest database schema with "migrations", as soon as the first database connection has been established.
database_class
my $class = $sql->database_class;
$sql = $sql->database_class('MyApp::Database');Class to be used by "db", defaults to Mojo::SQLite::Database. Note that this class needs to have already been loaded before "db" is called.
dsn
my $dsn = $sql->dsn;
$sql = $sql->dsn('dbi:SQLite:uri=file:foo.db');Data source name, defaults to dbi:SQLite:dbname= followed by a path to a temporary file.
max_connections
my $max = $sql->max_connections;
$sql = $sql->max_connections(3);Maximum number of idle database handles to cache for future use, defaults to 5.
migrations
my $migrations = $sql->migrations;
$sql = $sql->migrations(Mojo::SQLite::Migrations->new);Mojo::SQLite::Migrations object you can use to change your database schema more easily.
# Load migrations from file and migrate to latest version
$sql->migrations->from_file('/home/dbook/migrations.sql')->migrate;options
my $options = $sql->options;
$sql = $sql->options({AutoCommit => 1, RaiseError => 1});Options for database handles, defaults to activating sqlite_unicode, AutoCommit, AutoInactiveDestroy as well as RaiseError and deactivating PrintError. Note that AutoCommit and RaiseError are considered mandatory, so deactivating them would be very dangerous. See "ATTRIBUTES COMMON TO ALL HANDLES" in DBI and "DRIVER PRIVATE ATTRIBUTES" in DBD::SQLite for more information on available options.
pubsub
my $pubsub = $sql->pubsub;
$sql = $sql->pubsub(Mojo::SQLite::PubSub->new);Mojo::SQLite::PubSub object you can use to send and receive notifications very efficiently, by sharing a single database connection with many consumers.
# Subscribe to a channel
$sql->pubsub->listen(news => sub {
my ($pubsub, $payload) = @_;
say "Received: $payload";
});
# Notify a channel
$sql->pubsub->notify(news => 'SQLite rocks!');METHODS
Mojo::SQLite inherits all methods from Mojo::EventEmitter and implements the following new ones.
new
my $sql = Mojo::SQLite->new;
my $sql = Mojo::SQLite->new('file:test.db);
my $sql = Mojo::SQLite->new('sqlite:test.db');Construct a new Mojo::SQLite object and parse connection string with "from_string" if necessary.
# Customize configuration further
my $sql = Mojo::SQLite->new->dsn('dbi:SQLite:dbname=test.db');
my $sql = Mojo::SQLite->new->dsn('dbi:SQLite:uri=file:test.db?mode=memory');
# Pass filename directly
my $sql = Mojo::SQLite->new->from_filename($filename);db
my $db = $sql->db;Get a database object based on "database_class" for a cached or newly established database connection. The DBD::SQLite database handle will be automatically cached again when that object is destroyed, so you can handle problems like connection timeouts gracefully by holding on to it only for short amounts of time.
# Add up all the money
say $sql->db->query('select * from accounts')
->hashes->reduce(sub { $a->{money} + $b->{money} });from_filename
$sql = $sql->from_filename('C:\\Documents and Settings\\foo & bar.db', $options);Parse database filename directly. Unlike "from_string", the filename is parsed as a local filename and not a URL. A hashref of "options" may be passed as the second argument.
# Absolute filename
$sql->from_filename('/home/fred/data.db');
# Relative to current directory
$sql->from_filename('data.db');
# Temporary file database (default)
$sql->from_filename(':temp:');
# In-memory temporary database (single connection only)
my $db = $sql->from_filename(':memory:')->db;
# Additional options
$sql->from_filename($filename, { PrintError => 1 });from_string
$sql = $sql->from_string('test.db');
$sql = $sql->from_string('file:test.db');
$sql = $sql->from_string('file:///C:/foo/bar.db');
$sql = $sql->from_string('sqlite:C:%5Cfoo%5Cbar.db');Parse configuration from connection string. Connection strings are parsed as URLs, so you should construct them using a module like Mojo::URL, URI::file, or URI::db. For portability on non-Unix-like systems, either construct the URL with the sqlite scheme, or use "new" in URI::file to construct a URL with the file scheme. A URL with no scheme will be parsed as a file URL, and file URLs are parsed according to the current operating system. If specified, the hostname must be localhost. If the URL has a query string, it will be parsed and applied to "options".
# Absolute filename
$sql->from_string('sqlite:////home/fred/data.db');
$sql->from_string('sqlite://localhost//home/fred/data.db');
$sql->from_string('sqlite:/home/fred/data.db');
$sql->from_string('file:///home/fred/data.db');
$sql->from_string('file://localhost/home/fred/data.db');
$sql->from_string('file:/home/fred/data.db');
$sql->from_string('///home/fred/data.db');
$sql->from_string('//localhost/home/fred/data.db');
$sql->from_string('/home/fred/data.db');
# Relative to current directory
$sql->from_string('sqlite:data.db');
$sql->from_string('file:data.db');
$sql->from_string('data.db');
# Connection string must be a valid URL
$sql->from_string(Mojo::URL->new->scheme('sqlite')->path($filename));
$sql->from_string(URI::db->new->Mojo::Base::tap(engine => 'sqlite')->Mojo::Base::tap(dbname => $filename));
$sql->from_string(URI::file->new($filename));
# Temporary file database (default)
$sql->from_string(':temp:');
# In-memory temporary database (single connection only)
my $db = $sql->from_string(':memory:')->db;
# Additional options
$sql->from_string('data.db?PrintError=1&sqlite_allow_multiple_statements=1');
$sql->from_string(Mojo::URL->new->scheme('sqlite')->path($filename)->query(sqlite_see_if_its_a_number => 1));
$sql->from_string(URI::file->new($filename)->Mojo::Base::tap(query_form => {PrintError => 1}));REFERENCE
This is the class hierarchy of the Mojo::SQLite distribution.
BUGS
Report any issues on the public bugtracker.
AUTHOR
Dan Book, dbook@cpan.org
CREDITS
Sebastian Riedel, author of Mojo::Pg, which this distribution is based on.
COPYRIGHT AND LICENSE
Copyright 2015, Dan Book.
This library is free software; you may redistribute it and/or modify it under the terms of the Artistic License version 2.0.