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;
# Get a database handle from the cache for multiple queries
my $db = $sql->db;
# Use SQL::Abstract to generate simple CRUD queries for you
$db->insert('names', {name => 'Isabel'});
say $db->select('names', ['id'], {name => 'Isabel'})->hash->{id};
$db->update('names', {name => 'Bel'}, {name => 'Isabel'});
$db->delete('names', {name => 'Bel'});
# Insert a few rows
$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;
DESCRIPTION
Mojo::SQLite is a tiny wrapper around DBD::SQLite that makes SQLite
<https://www.sqlite.org/> a lot of fun to use with the Mojolicious
<https://mojolico.us> 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
<http://www.postgresql.org/docs/current/static/sql.html> 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
<https://www.sqlite.org/tempfiles.html> 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);
EXAMPLES
This distribution also contains a well-structured example blog
application
<https://github.com/kraih/mojo-pg/tree/master/examples/blog> you can
use for inspiration. This application shows how to apply the MVC design
pattern in practice.
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.
abstract
my $abstract = $sql->abstract;
$sql = $sql->abstract(SQL::Abstract->new);
SQL::Abstract object used to generate CRUD queries for
Mojo::SQLite::Database.
my($stmt, @bind) = $sql->abstract->select('names');
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
This attribute is DEPRECATED.
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->select('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}));
DEBUGGING
You can set the DBI_TRACE environment variable to get some advanced
diagnostics information printed by DBI.
DBI_TRACE=1
DBI_TRACE=15
DBI_TRACE=SQL
REFERENCE
This is the class hierarchy of the Mojo::SQLite distribution.
* Mojo::SQLite
* Mojo::SQLite::Database
* Mojo::SQLite::Migrations
* Mojo::SQLite::Results
* Mojo::SQLite::Transaction
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.
SEE ALSO
Mojolicious, Mojo::Pg, DBD::SQLite