Database Pool and Controller

This is a set of 3 classes for convenience of work with databases, a wrapper and sugar for PHP's PDO.

Classes

• Config: A class for preparing configuration for database connection. You can treat this as an alternative to common 'config.php' files, but it has a few potentially beneficial features:
  • Enforcing of useful security beneficial driver settings
  • Validation of some host parameters (like port number)
  • Convenient DSN generation using getDSN() function
  • Password protection that makes it a bit harder to spoof the password from outside functions, besides the appropriate Pool class
• Pool: A static proxy class which can pool database connection setups (\Simbiat\Database\Config objects) and use the one currently active, when you are requesting a PDO connection. With ability to change active connection, if required.
• Controller: a wrapper with some potentially useful features:
  • You can send both string (single query) and array (set of queries) and both will be processed. In case of array, it will automatically start a transaction and process each query separately. In case array will have any SELECT-like queries you will be notified, because their output may not get processed properly.
  • Attempts to retry in case of deadlock. You can set number of retries and time to sleep before each try using appropriate setters.
  • Binding sugar:
    • Instead of \PDO::PARAM_* or obscure integers you can send appropriate types as strings, like 'boolean'
    • Enforced type casting: it's known, that sometimes PDO driver does not cast or casts weirdly. Some cases enforce regular casting in attempt to work around this
    • Limit casting: when sending binding for use with LIMIT you need to remember to cast it as integer, but with this controller - just mark it as 'limit'
    • Like casting: when sending binding for use with LIKE you need to enclose it in % yourself, but with this controller - just mark it as 'like'
    • Date and time casting: mark a binding as 'date' or 'time' and script will attempt to check if it's a datetime value and convert it to an appropriate string for you. Or even get current time, if you do not want to use engine's own functions
  • Semantic wrappers: a set of functions for SELECT which clearly state, what they will be returning (row, column, everything)
  • Smart result return: if you send a single query, script will attempt to identify what it is and do either fetch() or fetchAll() or rowCount() and setting appropriate result. Drawback is that you need to use getResult() afterwards.

How to use

Please, note, that I am using MySQL as main DB engine in my projects, thus I may miss some peculiarities of other engines. Please, let me know of them, so that they can be incorporated.

First you need to create a \Config object and set its parameters like this:

$config = (new \Simbiat\Database\Config)->setUser('user')->setPassword('password')->setDB('database');

The above line is the minimum you will require. Additionally, you can set driver options like this:

$config->setOption(\PDO::MYSQL_ATTR_FOUND_ROWS, true)->setOption(\PDO::MYSQL_ATTR_INIT_COMMAND, 'SET @@global.character_set_client = \'utf8mb4\', @@global.character_set_connection = \'utf8mb4\', @@global.character_set_database = \'utf8mb4\', @@global.character_set_results = \'utf8mb4\', @@global.character_set_server = \'utf8mb4\', @@global.time_zone=\'+00:00\'');

After you set it up to your liking (can be done in one line), you need to add it to pool:

(new \Simbiat\Database\Pool)->openConnection($config, 'example');

Passing ID is not required but will improve your life if you will need to juggle multiple connections.

You can also pass the third argument (maxTries), if you want to have the script to retry connection, in case of failures. Default is 1.

If connection is established successfully you then can get \PDO object for it by not sending any parameters to the pool:

(new \Simbiat\Database\Pool)->openConnection();

Or sending a previous $config or connection ID if you need a specific one. \Controller class uses variant without parameters for flexibility, but can be overridden, if deemed necessary.

If connection failed, you will be able to get errors using

\Simbiat\Database\Pool::$errors

To utilize \Controller you need to establish as shown above and then call either it query() function or any of the wrappers. For example, this line will count rows in a table and return only the number of those rows, that is an integer:

(new \Simbiat\Database\Controller)->count('SELECT COUNT(*) FROM `table`');

This one will return a boolean, advising if something exists in a table:

(new \Simbiat\Database\Controller)->check('SELECT * FROM `table` WHERE `time`=:value', [':value'=>['', 'time']]);

The above example also shows one of possible ways to set bindings. Regular \PDO allows binding values like hook, value, type, but \Controller expects an array for value if you want to send a non-string one or a special value, like the above mentioned time. Since We are sending an empty value for time \Controller will take current microtime and convert and bind it in Y-m-d H:i:s.u format.