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Adapters for SQL database access

branch: develop-2
README.md

Aura.Sql

Provides an extension to the native PDO along with a profiler and connection locator. Because ExtendedPdo is an extension of the native PDO, code already using the native PDO or typehinted to the native PDO can use ExtendedPdo without any changes.

Added functionality in Aura.Sql over the native PDO includes:

  • Lazy connection. ExtendedPdo connects to the database only on method calls that require a connection. This means you can create an instance and not incur the cost of a connection if you never make a query.

  • Decoration. ExtendedPdo can be used to decorate an existing PDO instance. This means that a PDO instance can be "extended" at runtime to provide the ExtendedPdo behaviors. (Note that lazy connection is not possible in this case, as the PDO instance being decorated has already connected.)

  • Array quoting. The quote() method will accept an array as input, and return a string of comma-separated quoted values.

  • New perform() method. The perform() method acts just like query(), but binds values to a prepared statement as part of the call. In addition, placeholders that represent array values will be replaced with comma- separated quoted values. This means you can bind an array of values to a placeholder used with an IN (...) condition when using perform().

  • New fetch*() methods. The new fetch*() methods provide for commonly-used fetch actions. For example, you can call fetchAll() directly on the instance instead of having to prepare a statement, bind values, execute, and then fetch from the prepared statement. All of the fetch*() methods take an array of values to bind to to the query statement, and use the new perform() method internally.

  • Exceptions by default. ExtendedPdo starts in the ERRMODE_EXCEPTION mode for error reporting instead of the ERRMODE_SILENT mode.

  • Profiler. An optional query profiler is provided, along with an interface for other implementations.

  • Connection locator. A optional lazy-loading service locator is provided for picking different database connections (default, read, and write).

Foreword

Installation

This library requires PHP 5.3 or later, and has no userland dependencies.

It is installable and autoloadable via Composer as aura/sql.

Alternatively, download a release or clone this repository, then require or include its autoload.php file.

Quality

Scrutinizer Code Quality Code Coverage Build Status

To run the PHPUnit tests at the command line, go to the tests directory and issue phpunit.

This library attempts to comply with PSR-1, PSR-2, and PSR-4. If you notice compliance oversights, please send a patch via pull request.

Community

To ask questions, provide feedback, or otherwise communicate with the Aura community, please join our Google Group, follow @auraphp on Twitter, or chat with us on #auraphp on Freenode.

Getting Started

Instantiation

You can instantiate ExtendedPdo so that it uses lazy connection, or you can use it to decorate an existing PDO instance.

Lazy Connection Instance

Instantiation is the same as with the native PDO class: pass a data source name, username, password, and driver options. There is one additional parameter that allows you to pass attributes to be set after the connection is made.

<?php
use Aura\Sql\ExtendedPdo;

$pdo = new ExtendedPdo(
    'mysql:host=localhost;dbname=test',
    'username',
    'password',
    array(), // driver options as key-value pairs
    array()  // attributes as key-value pairs
);
?>

Whereas the native PDO connects on instantiation, ExtendedPdo does not connect immediately. Instead, it connects only when you call a method that actually needs the connection to the database; e.g., on query().

If you want to force a connection, call the connect() method.

<?php
// does not connect to the database
$pdo = new ExtendedPdo(
    'mysql:host=localhost;dbname=test',
    'username',
    'password'
);

// automatically connects
$pdo->exec('SELECT * FROM test');

// explicitly forces a connection
$pdo->connect();
?>

Decorator Instance

The ExtendedPdo class can be used to decorate an existing PDO connection as well. To do so, instantiate ExtendedPdo by passing an existing PDO connection:

<?php
use Aura\Sql\ExtendedPdo;

$pdo = new PDO(...);
$extended_pdo = new ExtendedPdo($pdo);
?>

The decorated PDO instance now provides all the ExtendedPdo functionality (aside from lazy connection, which is not possible since the PDO instance by definition has already connected).

Decoration of this kind can be useful when you have access to an existing PDO connection managed elsewhere in your application.

Array Quoting

The native PDO quote() method will not quote arrays. This makes it difficult to bind an array to something like an IN (...) condition in SQL. However, ExtendedPdo recognizes arrays and converts them into comma- separated quoted strings.

<?php
// the array to be quoted
$array = array('foo', 'bar', 'baz');

// the native PDO way:
// "Warning:  PDO::quote() expects parameter 1 to be string, array given"
$pdo = new PDO(...);
$cond = 'IN (' . $pdo->quote($array) . ')';

// the ExtendedPdo way:
// "IN ('foo', 'bar', 'baz')"
$pdo = new ExtendedPdo(...);
$cond = 'IN (' . $pdo->quote($array) . ')'; 
?>

The perform() Method

The new perform() method will prepare a query with bound values in a single step. Also, because the native PDO does not deal with bound array values, perform() modifies the query string to replace array-bound placeholders with the quoted array. Note that this is not the same thing as binding: the query string itself is modified before passing to the database for value binding.

<?php
// the array to be quoted
$array = array('foo', 'bar', 'baz');

// the statement to prepare
$stm = 'SELECT * FROM test WHERE foo IN (:foo)'

// the native PDO way does not work (PHP Notice:  Array to string conversion)
$pdo = new ExtendedPdo(...);
$sth = $pdo->prepare($stm);
$sth->bindValue('foo', $array);

// the ExtendedPdo way allows a single call to prepare and execute the query.
// it quotes the array and replaces the array placeholder directly in the 
// query string
$pdo = new ExtendedPdo(...);
$bind_values = array('foo' => $array);
$sth = $pdo->perform($stm, $bind_values);
echo $sth->queryString;
// the query string has been modified by ExtendedPdo to become
// "SELECT * FROM test WHERE foo IN ('foo', 'bar', 'baz')"
?>

Finally, note that array quoting works only via the perform() method, not on returned PDOStatement instances.

New fetch*() Methods

ExtendedPdo comes with fetch*() methods to help reduce boilerplate code. Instead of issuing prepare(), a series of bindValue() calls, execute(), and then fetch*() on a PDOStatement, you can bind values and fetch results in one call on ExtendedPdo directly. (The fetch*() methods use perform() internally, so quoting-and-replacement of array placeholders is supported.)

<?php
$stm  = 'SELECT * FROM test WHERE foo = :foo AND bar = :bar';
$bind = array('foo' => 'bar', 'baz' => 'dib');

// the native PDO way to "fetch all" where the result is a sequential array
// of rows, and the row arrays are keyed on the column names
$pdo = new PDO(...);
$sth = $pdo->prepare($stm);
$sth->execute($bind);
$result = $sth->fetchAll(PDO::FETCH_ASSOC);

// the ExtendedPdo way to do the same kind of "fetch all"
$pdo = new ExtendedPdo(...);
$result = $pdo->fetchAll($stm, $bind);

// fetchAssoc() returns an associative array of all rows where the key is the
// first column, and the row arrays are keyed on the column names
$result = $pdo->fetchAssoc($stm, $bind);

// fetchCol() returns a sequential array of all values in the first column
$result = $pdo->fetchCol($stm, $bind);

// fetchObject() returns the first row as an object of your choosing; the
// columns are mapped to object properties. an optional 4th parameter array
// provides constructor arguments when instantiating the object.
$result = $pdo->fetchObject($stm, $bind, 'ClassName', array('ctor_arg_1'));

// fetchObjects() returns an array of objects of your choosing; the
// columns are mapped to object properties. an optional 4th parameter array
// provides constructor arguments when instantiating the object.
$result = $pdo->fetchObjects($stm, $bind, 'ClassName', array('ctor_arg_1'));

// fetchOne() returns the first row as an associative array where the keys
// are the column names
$result = $pdo->fetchOne($stm, $bind);

// fetchPairs() returns an associative array where each key is the first
// column and each value is the second column
$result = $pdo->fetchPairs($stm, $bind);

// fetchValue() returns the value of the first row in the first column
$result = $pdo->fetchValue($stm, $bind);

// fetchAffected() returns the number of affected rows
$stm = "UPDATE test SET incr = incr + 1 WHERE foo = :foo AND bar = :bar";
$row_count = $pdo->fetchAffected($stm, $bind);
?>

The methods fetchAll(), fetchAssoc(), fetchCol(), and fetchPairs() take an optional third parameter, a callable, to apply to each row of the results before returning.

<?php
$result = $pdo->fetchAssoc($stm, $bind, function (&$row) {
    // add a column to the row
    $row['my_new_col'] = 'Added this column from the callable.';
});
?>

Profiler

When debugging, it is often useful to see what queries have been executed, where they were issued from in the codebase, and how long they took to complete. ExtendedPdo comes with an optional profiler that you can use to discover that information.

<?php
use Aura\Sql\ExtendedPdo;
use Aura\Sql\Profiler;

$pdo = new ExtendedPdo(...);
$pdo->setProfiler(new Profiler);

// ...
// query(), fetch(), beginTransaction()/commit()/rollback() etc.
// ...

// now retrieve the profile information:
$profiles = $pdo->getProfiler()->getProfiles();
?>

Each profile entry will have these keys:

  • duration: How long the query took to complete, in seconds.

  • function: The method that was called on ExtendedPdo that created the profile entry.

  • statement: The query string that was issued, if any. (Methods like connect() and rollBack() do not send query strings.)

  • bind_values: Any values that were bound to the query.

  • trace: An exception stack trace indicating where the query was issued from in the codebase.

Setting the Profiler into the ExtendedPdo instance is optional. Once it is set, you can activate and deactivate it as you wish using the Profiler::setActive() method. When not active, query profiles will not be retained.

<?php
$pdo = new ExtendedPdo(...);
$pdo->setProfiler(new Profiler);

// deactivate, issue a query, and reactivate;
// the query will not show up in the profiles
$pdo->getProfiler()->setActive(false);
$pdo->fetchAll('SELECT * FROM foo');
$pdo->getProfiler()->setActive(true);
?>

Connection Locator

Frequently, high-traffic PHP applications use multiple database servers, generally one for writes, and one or more for reads. The ConnectionLocator allows you to define multiple ExtendedPdo objects for lazy-loaded read and write connections. It will create the connections only when they are when called. The creation logic is wrapped in a callable.

First, create the ConnectionLocator:

<?php
use Aura\Sql\ExtendedPdo;
use Aura\Sql\ConnectionLocator;

$connections = new ConnectionLocator;
?>

Now add a default connection; this will be used when a read or write connection is not defined. (This is also useful for setting up connection location in advance of actually having multiple database servers.)

<?php
$connections->setDefault(function () {
    return new ExtendedPdo(
        'mysql:host=default.db.localhost;dbname=database',
        'username',
        'password'
    );
});
?>

Next, add as many named read and write connections as you like:

<?php
// the write (master) server
$connections->setWrite('master', function () {
    return new ExtendedPdo(
        'mysql:host=master.db.localhost;dbname=database',
        'username',
        'password'
    );
});

// read (slave) #1
$connections->setRead('slave1', function () {
    return new ExtendedPdo(
        'mysql:host=slave1.db.localhost;dbname=database',
        'username',
        'password'
    );
});

// read (slave) #2
$connections->setRead('slave2', function () {
    return new ExtendedPdo(
        'mysql:host=slave2.db.localhost;dbname=database',
        'username',
        'password'
    );
});

// read (slave) #3
$connections->setRead('slave3', function () {
    return new ExtendedPdo(
        'mysql:host=slave3.db.localhost;dbname=database',
        'username',
        'password'
    );
});
?>

Finally, retrieve a connection from the locator when you need it. This will create the connection (if needed) and then return it.

  • getDefault() will return the default connection.

  • getRead() will return a named read connection; if no name is specified, it will return a random read connection. If no read connections are defined, it will return the default connection.

  • getWrite() will return a named write connection; if no name is specified, it will return a random write connection. If no write connections are defined, it will return the default connection.

<?php
$read = $connections->getRead();
$results = $read->fetchAll('SELECT * FROM table_name LIMIT 10');
?>

Construction-Time Configuration

The ConnectionLocator can be configured with all its connections at construction time; this is useful with dependency injection mechanisms.

<?php
use Aura\Sql\ConnectionLocator;
use Aura\Sql\ExtendedPdo;

// default connection
$default = function () {
    return new ExtendedPdo(
        'mysql:host=default.db.localhost;dbname=database',
        'username',
        'password'
    );
};

// read connections
$read = array(
    'slave1' => function () {
        return new ExtendedPdo(
            'mysql:host=slave1.db.localhost;dbname=database',
            'username',
            'password'
        );
    },
    'slave2' => function () {
        return new ExtendedPdo(
            'mysql:host=slave2.db.localhost;dbname=database',
            'username',
            'password'
        );
    },
    'slave3' => function () {
        return new ExtendedPdo(
            'mysql:host=slave3.db.localhost;dbname=database',
            'username',
            'password'
        );
    },
);

// write connection
$write = array(
    'master' => function () {
        return new ExtendedPdo(
            'mysql:host=master.db.localhost;dbname=database',
            'username',
            'password'
        );
    },
);

// configure locator at construction time
$connections = new ConnectionLocator($default, $read, $write);
?>
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