Provided by: libmojo-sqlite-perl_3.003-1_all 
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'});
my $id = $db->select('names', ['id'], {name => 'Isabel'})->hash->{id};
$db->update('names', {name => 'Bel'}, {id => $id});
$db->delete('names', {name => 'Bel'});
# Insert a few rows in a transaction with SQL and placeholders
eval {
my $tx = $db->begin;
$db->query('insert into names (name) values (?)', 'Sara');
$db->query('insert into names (name) values (?)', 'Stefan');
$tx->commit;
};
say $@ if $@;
# Insert another row with SQL::Abstract and return the generated id
say $db->insert('names', {name => '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 with SQL::Abstract
say $_->{name} for $db->select('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. Use all SQL features
<http://sqlite.org/lang.html> SQLite has to offer, generate CRUD queries from data structures, and manage
your database schema with migrations.
BASICS
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). You can prevent this mode from being enabled by passing the option
"no_wal", but note that this is incompatible with SQLite databases that have already had WAL mode
enabled. See <http://sqlite.org/wal.html> and "journal_mode" in DBD::SQLite 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);
SQL::Abstract::Pg can provide additional features to the SQL::Abstract query methods in
Mojo::SQLite::Database. The "on_conflict" and "for" features are not applicable to SQLite queries.
use SQL::Abstract::Pg;
my $sql = Mojo::SQLite->new(abstract => SQL::Abstract::Pg->new(name_sep => '.', quote_char => '"'));
$sql->db->select(['some_table', ['other_table', foo_id => 'id']],
['foo', [bar => 'baz'], \q{datetime('now') as dt}],
{foo => 'value'},
{order_by => 'foo', limit => 10, offset => 5, group_by => ['foo'], having => {baz => 'value'}});
EXAMPLES
This distribution also contains a well-structured example blog application
<https://github.com/Grinnz/Mojo-SQLite/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 = $sql->abstract(SQL::Abstract->new);
SQL::Abstract object used to generate CRUD queries for Mojo::SQLite::Database, defaults to setting
"name_sep" to "." and "quote_char" to """. SQL::Abstract::Pg may be used to provide additional features.
# Generate WHERE clause and bind values
my($stmt, @bind) = $sql->abstract->where({foo => 'bar', baz => 'yada'});
auto_migrate
my $bool = $sql->auto_migrate;
$sql = $sql->auto_migrate($bool);
Automatically migrate to the latest database schema with "migrations", as soon as "db" has been called
for the first time.
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 1.
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.
parent
my $parent = $sql->parent;
$sql = $sql->parent(Mojo::SQLite->new);
Another Mojo::SQLite object to use for connection management, instead of establishing and caching our own
database connections.
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');
my $sql = Mojo::SQLite->new(Mojo::SQLite->new);
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" (which is usually Mojo::SQLite::Database) 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 });
# Readonly connection without WAL mode
$sql->from_filename($filename, { ReadOnly => 1, no_wal => 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');
$sql = $sql->from_string(Mojo::SQLite->new);
Parse configuration from connection string or use another Mojo::SQLite object as "parent". 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}));
# Readonly connection without WAL mode
$sql->from_string('data.db?ReadOnly=1&no_wal=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
perl v5.30.0 2019-10-22 Mojo::SQLite(3pm)