Introduction to Connections

DSN, the Data Source Name

In order to connect to a database through Doctrine, you have to create a valid DSN (Data Source Name).

Doctrine supports both PEAR DB/MDB2 like data source names as well as PDO style data source names. The following section deals with PEAR like data source names. If you need more info about the PDO-style data source names see the documentation on PDO.

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phptype(dbsyntax)://username:password@protocol+hostspec/database?option=value

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phptype://username:password@protocol+hostspec:110//usr/db_file.db
phptype://username:password@hostspec/database
phptype://username:password@hostspec
phptype://username@hostspec
phptype://hostspec/database phptype://hostspec phptype:///database
phptype:///database?option=value&anotheroption=anothervalue
phptype(dbsyntax) phptype
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phptype(syntax)://user:pass@protocol(proto_opts)/database

Opening New Connections

Opening a new database connection in Doctrine is very easy. If you wish to use PDO you can just initialize a new PDO object.

Remember our bootstrap.php file we created in the Getting Started chapter? Under the code where we registered the Doctrine autoloader we are going to instantiate our new connection:

// bootstrap.php
$ dsn = 'mysql:dbname=testdb;host=127.0.0.1';
$ user = 'dbuser';
$ password = 'dbpass';

$ dbh = new PDO($dsn, $user, $password);
$ conn = Doctrine_Manager::connection($dbh);

// bootstrap.php
$ conn->setOption('username', $user);
$ conn->setOption('password', $password);

Lazy Database Connecting

Lazy-connecting to database can save a lot of resources. There might be many times where you don't need an actual database connection, hence its always recommended to use lazy-connecting (that means Doctrine will only connect to database when needed).

This feature can be very useful when using for example page caching, hence not actually needing a database connection on every request. Remember connecting to database is an expensive operation.

In the example below we will show you when you create a new Doctrine connection, the connection to the database isn't created until it is actually needed.

// bootstrap.php
// At this point no actual connection to the database is created
$ conn = Doctrine_Manager::connection('mysql://username:password@localhost/test');

// The first time the connection is needed, it is instantiated
// This query triggers the connection to be created
$ conn->execute('SHOW TABLES');

Testing your Connection

After reading the previous sections of this chapter, you should now know how to create a connection. So, lets modify our bootstrap file to include the initialization of a connection. For this example we will just be using a sqlite memory database but you can use whatever type of database connection you prefer.

Add your database connection to bootstrap.php and it should look something like the following:

/* Bootstrap Doctrine.php, register autoloader and specify
   configuration attributes */

require_once('../doctrine/branches/1.2/lib/Doctrine.php');
spl_autoload_register(array('Doctrine', 'autoload'));
$ manager = Doctrine_Manager::getInstance();

$ conn = Doctrine_Manager::connection('sqlite::memory:', 'doctrine');

To test the connection lets modify our test.php script and perform a small test. Since we create a variable name $conn, that variable is available to the test script so lets setup a small test to make sure our connection is working:

First lets create a test table and insert a record:

// test.php
$ conn->export->createTable('test', array('name' => array('type' => 'string')));
$ conn->execute('INSERT INTO test (name) VALUES (?)', array('jwage'));

Now lets execute a simple SELECT query from the test table we just created to make sure the data was inserted and that we can retrieve it:

// test.php
$ stmt = $conn->prepare('SELECT \* FROM test');
$ stmt->execute();
$ results = $stmt->fetchAll();
print_r($results);

Execute test.php from your terminal and you should see:

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php test.php
Array(
  [0] => Array(
    [name] => jwage,
    [0] => jwage
  )
)
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Conclusion

Great! Now we learned some basic operations of Doctrine connections. We have modified our Doctrine test environment to have a new connection. This is required because the examples in the coming chapters will require a connection.

Lets move on to the Configuration chapter and learn how you can control functionality and configurations using the Doctrine attribute system.