Setup database connection. Phew, that took longer than expected!

logic/Actions/FetchData.php

@@ -8,8 +8,10 @@ class FetchData {
 	private $validator;
 	
 	public function __construct(
-		\SBRL\TomlConfig $in_settings) {
+		\SBRL\TomlConfig $in_settings,
+		\AirQuality\Database $in_database) {
 		$this->settings = $in_settings;
+		$this->database = $in_database;
 		$this->validator = new \AirQuality\Validator($_GET);
 	}
 	

logic/Database.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace AirQuality;
+
+/**
+ * Holds the main database connection.
+ */
+class Database
+{
+	// Whether the database connection should be read only or not.
+	// Defaults to true, as we don't need to write _anything_ to the database.
+	private const read_only = true;
+	private $connection;
+	
+	private $pdo_options = [
+		// https://devdocs.io/php/pdo.setattribute
+	    PDO::ATTR_ERRMODE				=> PDO::ERRMODE_EXCEPTION,
+	    PDO::ATTR_DEFAULT_FETCH_MODE	=> PDO::FETCH_ASSOC,
+	    PDO::ATTR_EMULATE_PREPARES		=> false,
+		PDO::ATTR_AUTOCOMMIT			=> false
+	];
+	
+	function __construct(\SBRL\TomlConfig $in_settings) {
+		$this->settings = $in_settings;
+	}
+	
+	public function connect() {
+		$this->connection = new \PDO(
+			$this->get_connection_string(),
+			$this->settings->get("database.username"),
+			$this->settings->get("database.password"),
+		);
+		// Make this connection read-only
+		if(self::read_only)
+			$this->connection->query("SET SESSION TRANSACTION READ ONLY;");
+	}
+	
+	public function query($sql, $variables) {
+		// FUTURE: Optionally cache prepared statements?
+		return $this->connection->prepare($sql)->execute($variables);
+	}
+	
+	private function get_connection_string() {
+		return "{$this->settings->get("database.type")}:host={$this->settings->get("database.host")};dbname={$this->settings->get("database.name")};charset=utf8mb4";
+	}
+}

settings.default.toml

@@ -7,8 +7,15 @@
 # Settings that control the database, or the connection to it
 
 type = "mysql" # MariaDB. MySQL servers might work too, but no promises.
-database_name = "aq_db"
+
+# The host that the database is running on. Both IP addresses & domain names are fine :-)
+host = "localhost"
+# The database to use.
+name = "aq_db"
+
+# The username to connect with
 username = "user"
+# the password to connect with
 password = "Define_in_custom_config_file"
 
 [routing]