PDO bolt

The PHP Data Objects (PDO) extension defines a lightweight, consistent interface for accessing databases in PHP. This library is dedicated to add bolt protocol. This protocol was created by Neo4j and is used by graph databases like Neo4j, Memgraph or Amazon Neptune.

Right now there is no official C/C++ bolt driver and therefore it is not possible to make this library as extension. Even the unofficial driver looks like it is not maintained. Maybe in future it will change but before that you are welcomed to use this one.

Bolt specification

Requirements

• PHP ^8
• Bolt library

Installation

You can use composer or download this repository from GitHub and manually implement it.

Composer

Run the following command in your project to install the latest applicable version of the package:

composer require stefanak-michal/pdo-bolt

Packagist

Usage

You can use this library as typical PDO, but you have to create instance of \pdo_bolt\PDO which overrides \PDO and adds bolt scheme.

$pdo = new \pdo_bolt\PDO('bolt:host=localhost;port=7687;appname=pdo-bolt', 'neo4j', 'neo4j');
$stmt = $pdo->prepare('RETURN $n AS num, $s AS str');
$stmt->bindValue('n', 123, \PDO::PARAM_INT);
$stmt->bindValue('s', 'hello');
$stmt->execute();
$stmt->setFetchMode(\PDO::FETCH_ASSOC);
foreach ($stmt AS $row) {
    print_r($row);
}

/* output:
Array
(
    [num] => 123
    [str] => hello
)
*/

For more information about how to use PDO follow official documentation at php.net.

DSN

Key	Description
host	The hostname on which the database server resides.
port	The port number where the database server is listening.
dbname	The name of the database.
appname	The application name (used as UserAgent).

PDO constructor available options

Key	Description
auth	Specify authentication method (none/basic/bearer/kerberos). Automatically detected.
ssl	Enable encrypted communication and set ssl context options (see php.net)
protocol_versions	Specify requested bolt versions. Array of versions as int/float/string.

Check method annotation for more informations.

Yii framework

You can use this library with Yii framework in very simple way. Just set up in configuration your PDO class.

https://www.yiiframework.com/doc/api/2.0/yii-db-connection#$pdoClass-detail

Bolt specific features

Parameter placeholders

Supported parameter placeholder for CQL is ? or string with $ prefix.

Don't use placeholder string with : prefix because CQL use : for labels prefix.

PDO Method reset()

Graph database can be in failure state (error code 02001) and any next message is ignored (error code 02002). Instead of destroying PDO instance and creating new, you can call this method.

PDO::PARAM_LOB

Automatically converts resource or string into instance of Bytes class.

Additional bolt parameter types

Constant	Description
PDO::BOLT_PARAM_FLOAT
PDO::BOLT_PARAM_LIST	Array witch consecutive numeric keys from 0.
PDO::BOLT_PARAM_DICTIONARY	Object or array which is not list.
PDO::BOLT_PARAM_STRUCTURE	Class extending IStructure.
PDO::BOLT_PARAM_BYTES	instance of Bytes class.

List of usable parameters depends on graph database you use (Neo4j, Memgraph).

Not supported PDO features with Bolt

• Fetch mode PDO::FETCH_LAZY
• Fetch mode PDO::FETCH_NAMED
• PDO method lastInsertId()
• PDOStatement method rowCount()
• Scrollable cursor

Bolt error codes

Standard PDO error codes are related to SQL databases. Graph database have CQL (Cypher query language) and therefore I had to create new list of error codes.

Error code	Description
01000	Any authentification error
01001	Wrong credentials
01002	Undefined auth type
02000	Any bolt message error
02001	Bolt message failure
02002	Bolt message ignored
03000	Any transaction error
03001	Transaction not supported (required bolt>=3
04000	Any attribute error
04001	Attribute not supported
05000	Any parameter error
05001	Parameter type not supported
05002	Parameters placeholder mismatch
06000	Any fetch error
06001	Requested fetch column not defined
06002	Fetch object error
07000	Any underlying bolt library error