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https://github.com/grinnz/mojo-sqlite

Mojo::SQLite - A tiny Mojolicious wrapper for SQLite
https://github.com/grinnz/mojo-sqlite

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Mojo::SQLite - A tiny Mojolicious wrapper for SQLite

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README 

        
=pod



=head1 NAME



Mojo::SQLite - A tiny Mojolicious wrapper for SQLite



=head1 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(<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;



=head1 DESCRIPTION



L is a tiny wrapper around L that makes

L a lot of fun to use with the

L real-time web framework. Use all

L SQLite has to offer, generate CRUD

queries from data structures, and manage your database schema with migrations.



=head1 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 ($c) {

    my $db = $c->sqlite->db;

    $c->render(json => $db->query(q{select datetime('now','localtime') as now})->hash);

  };



  app->start;



In this example application, we create a C helper to store a

L object. Our action calls that helper and uses the method

L to dequeue a L object from the

connection pool. Then we use the method L to

execute an L

statement, which returns a L object. And finally we call

the method L to retrieve the first row as a hash

reference.



All I/O and queries are performed synchronously, and SQLite's default journal

mode only supports concurrent reads from multiple processes while the database

is not being written. The "Write-Ahead Log" journal mode allows multiple

processes to read and write concurrently to the same database file (but only

one can write at a time). WAL mode is enabled by the C option,

currently enabled by default, and persists when opening that same database in

the future.



  # Performed concurrently (concurrent with writing only with WAL journaling mode)

  my $pid = fork || die $!;

  say $sql->db->query(q{select datetime('now','localtime') as time})->hash->{time};

  exit unless $pid;



The C option prevents WAL mode from being enabled in new databases but

doesn't affect databases where it has already been enabled. C may not

be set by default in a future release. See L and

L for more information.



The L is

disabled for all connections since Mojo::SQLite 3.003; use single quotes for

string literals and double quotes for identifiers, as is normally recommended.



All cached database handles will be reset automatically if a new process has

been forked, this allows multiple processes to share the same L

object safely.



Any database errors will throw an exception as C is automatically

enabled, so use C or L to catch them. This makes transactions

with L easy.



While passing a file path of C<:memory:> (or a custom L"dsn"> with

C) will create a temporary database, in-memory databases cannot be

shared between connections, so subsequent calls to L"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 C<:temp:>

to store the database in a temporary directory (this is the default), or

consider constructing a temporary directory yourself with L if you

need to reuse the filename. A temporary directory allows SQLite to create

L 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);



=head1 EXAMPLES



This distribution also contains a well-structured example

L

you can use for inspiration. This application shows how to apply the MVC design

pattern in practice.



=head1 EVENTS



L inherits all events from L and can emit the

following new ones.



=head2 connection



  $sql->on(connection => sub ($sql, $dbh) {

    $dbh->do('pragma journal_size_limit=1000000');

  });



Emitted when a new database connection has been established.



=head1 ATTRIBUTES



L implements the following attributes.



=head2 abstract



  my $abstract = $sql->abstract;

  $sql         = $sql->abstract(SQL::Abstract->new);



L object used to generate CRUD queries for

L, defaults to a L object with

C set to C<.> and C set to C<">.



  # Generate WHERE clause and bind values

  my($stmt, @bind) = $sql->abstract->where({foo => 'bar', baz => 'yada'});



L provides additional features to the L

query methods in L such as C<-json> and

C/C. The C feature is not applicable to SQLite queries.



  $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'}});



  # Upsert supported since SQLite 3.24.0

  $sql->db->insert('some_table', {name => $name, value => $value},

    {on_conflict => [name => {value => \'"excluded"."value"'}]});



=head2 auto_migrate



  my $bool = $sql->auto_migrate;

  $sql     = $sql->auto_migrate($bool);



Automatically migrate to the latest database schema with L"migrations">, as

soon as L"db"> has been called for the first time.



=head2 database_class



  my $class = $sql->database_class;

  $sql      = $sql->database_class('MyApp::Database');



Class to be used by L"db">, defaults to L. Note that

this class needs to have already been loaded before L"db"> is called.



=head2 dsn



  my $dsn = $sql->dsn;

  $sql    = $sql->dsn('dbi:SQLite:uri=file:foo.db');



Data source name, defaults to C followed by a path to a

temporary file.



=head2 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

C<1>.



=head2 migrations



  my $migrations = $sql->migrations;

  $sql           = $sql->migrations(Mojo::SQLite::Migrations->new);



L 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;



=head2 options



  my $options = $sql->options;

  $sql        = $sql->options({AutoCommit => 1, RaiseError => 1});



Options for database handles, defaults to setting C to

C, setting C,

C and C, and deactivating C.

Note that C and C are considered mandatory, so

deactivating them would be very dangerous. See

L and

L for more information on available

options.



=head2 parent



  my $parent = $sql->parent;

  $sql       = $sql->parent(Mojo::SQLite->new);



Another L object to use for connection management, instead of

establishing and caching our own database connections.



=head1 METHODS



L inherits all methods from L and implements

the following new ones.



=head2 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 L object and parse connection string with

L"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);



=head2 db



  my $db = $sql->db;



Get a database object based on L"database_class"> (which is usually

L) for a cached or newly established database

connection. The L 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} });



=head2 from_filename



  $sql = $sql->from_filename('C:\\Documents and Settings\\foo & bar.db', $options);



Parse database filename directly. Unlike L"from_string">, the filename is

parsed as a local filename and not a URL. A hashref of L"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 });

  

  # Strict unicode strings and WAL mode

  use DBD::SQLite::Constants ':dbd_sqlite_string_mode';

  $sql->from_filename($filename, { sqlite_string_mode => DBD_SQLITE_STRING_MODE_UNICODE_STRICT, wal_mode => 1 });



=head2 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 L

object as L"parent">. Connection strings are parsed as URLs, so you should

construct them using a module like L, L, or L.

For portability on non-Unix-like systems, either construct the URL with the

C scheme, or use L to construct a URL with the C

scheme. A URL with no scheme will be parsed as a C URL, and C URLs

are parsed according to the current operating system. If specified, the

hostname must be C. If the URL has a query string, it will be parsed

and applied to L"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');



  # String unicode strings and WAL mode

  use DBD::SQLite::Constants ':dbd_sqlite_string_mode';

  $sql->from_string(Mojo::URL->new->scheme('sqlite')->path('data.db')

    ->query(sqlite_string_mode => DBD_SQLITE_STRING_MODE_UNICODE_STRICT, wal_mode => 1));



=head1 DEBUGGING



You can set the C environment variable to get some advanced

diagnostics information printed by L.



  DBI_TRACE=1

  DBI_TRACE=15

  DBI_TRACE=SQL



=head1 REFERENCE



This is the class hierarchy of the L distribution.



=over 2



=item * L



=item * L



=item * L



=item * L



=item * L



=back



=head1 BUGS



Report any issues on the public bugtracker.



=head1 AUTHOR



Dan Book, C



=head1 CREDITS



Sebastian Riedel, author of L, which this distribution is based on.



=head1 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.



=head1 SEE ALSO



L, L, L



=cut