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__construct()

public function __construct(?string $module_name = null, ?string $db_group = null)

Description

Initializes a database connection using PDO with configuration from config/database.php. Supports multiple database groups and provides environment‑aware error handling (detailed errors in development, generic errors in production). The constructor also blocks direct URL access to the Db module for security.

IMPORTANT: The framework automatically passes the module name as the first parameter when instantiating Db via $this->db. When creating Db instances manually, you can omit the module name.

Parameters

Parameter Type Description Default Required
module_name string|null The module name (passed by framework for integration with Trongate module system). Can be null for manual instantiation. null No
db_group string|null Database group name from config/database.php (defaults to 'default'). null No

Return Value

Type Description
void No return value.

Exceptions

  • Exception - If the specified database group is not configured in /config/database.php.
  • Exception - If the database connection fails.

Example #1: Framework Instantiation (Typical Usage)

In controllers and models, Db is automatically available via $this->db:

PHP
<?php
class Products extends Trongate {
    public function index() {
        // $this->db is already instantiated by the framework
        $products = $this->db->get('id', 'products');
        // ...
    }
}

Example #2: Manual Instantiation with Default Database

Creating a Db instance manually (outside framework context):

PHP
// Uses 'default' database group from config/database.php
$db = new Db();

// Now use like any Db instance
$users = $db->get('id', 'users');

Example #3: Manual Instantiation with Specific Database Group

Connecting to an alternative database defined in config/database.php:

PHP
// Connect to 'analytics' database group
$analytics_db = new Db(null, 'analytics');

// Query the analytics database
$stats = $analytics_db->get('date', 'page_views');

Example #4: Framework Instantiation with Custom Database Group

Within a module, you can load Db with a specific database group:

PHP
<?php
class Reports extends Trongate {
    public function __construct() {
        parent::__construct();
        // Load Db with 'analytics' database group
        $this->module('db', 'analytics');
        // Now $this->db points to the analytics database
    }
    
    public function index() {
        $data = $this->db->get('id', 'analytics_data');
        // ...
    }
}

Configuration Example (config/database.php)

PHP
$databases['default'] = [
    'host' => 'localhost',
    'port' => '3306',
    'user' => 'root',
    'password' => 'secret',
    'database' => 'myapp'
];

$databases['analytics'] = [
    'host' => 'analytics.db.example.com',
    'port' => '3306',
    'user' => 'analytics_user',
    'password' => 'analytics_pass',
    'database' => 'analytics_db'
];

Important Notes

  • Always calls parent::__construct($module_name) first (required by framework).
  • Blocks URL access to the Db module via block_url('db') for security.
  • Determines environment mode (dev/prod) from the ENV constant.
  • Uses persistent PDO connections by default (PDO::ATTR_PERSISTENT => true).
  • Sets error mode to PDO::ERRMODE_EXCEPTION.
  • If the database name is empty in configuration, returns without connecting (useful for tests).
  • In development mode (ENV === 'dev'), errors include detailed messages.
  • In production mode, errors are generic to avoid leaking sensitive information.
  • The $module_name parameter is primarily for framework integration; you can ignore it when creating instances manually.