Start on project with the connection services and first command to list databases

.env

@@ -17,3 +17,7 @@
 APP_ENV=dev
 APP_SECRET=c38de86853448126a1e57bd9dbe6760e
 ###< symfony/framework-bundle ###
+
+DATABASE_HOSTNAME=localhost
+DATABASE_USER=user
+DATABASE_PASSWORD=password

composer.json

@@ -4,7 +4,7 @@
   "minimum-stability": "stable",
   "prefer-stable": true,
   "require": {
-        "php": ">=7.2.5",
+    "php": ">=8.0",
     "ext-ctype": "*",
     "ext-iconv": "*",
     "symfony/console": "5.3.*",
@@ -12,7 +12,8 @@
     "symfony/flex": "^1.3.1",
     "symfony/framework-bundle": "5.3.*",
     "symfony/runtime": "5.3.*",
-        "symfony/yaml": "5.3.*"
+    "symfony/yaml": "5.3.*",
+    "ext-mysqli": "*"
   },
   "require-dev": {
   },

composer.lock

@@ -2684,6 +2684,8 @@
         "ext-ctype": "*",
         "ext-iconv": "*"
     },
-    "platform-dev": [],
+    "platform-dev": {
+        "php": "*"
+    },
     "plugin-api-version": "2.1.0"
 }

config/services.yaml

@@ -23,3 +23,9 @@ services:
 
     # add more service definitions when explicit configuration is needed
     # please note that last definitions always *replace* previous ones
+
+    App\Service\MysqliConnection:
+        arguments:
+            $hostname: '%env(string:DATABASE_HOSTNAME)%'
+            $user: '%env(string:DATABASE_USER)%'
+            $password: '%env(DATABASE_PASSWORD)%'

src/Console/ListDatabasesCommand.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Console;
+
+use App\Service\DatabaseManager;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+class ListDatabasesCommand extends Command
+{
+    // the name of the command (the part after "bin/console")
+    protected static $defaultName = 'app:db:list';
+
+    public function __construct(
+        private DatabaseManager $db,
+    )
+    {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        // ...
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $dbs = $this->db->listDatabases();
+
+        $output->writeln('List of databases:');
+        foreach ($dbs as $db) {
+            $output->writeln(sprintf(' -%s', $db));
+        }
+
+        return Command::SUCCESS;
+    }
+}

src/Service/DatabaseManager.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Service;
+
+use mysqli;
+
+class DatabaseManager
+{
+    private mysqli $conn;
+
+    public function __construct(
+        private MysqliConnection $service
+    )
+    {
+        $this->conn = $this->service->getConnection();
+    }
+
+    public function listDatabases(): array
+    {
+        $dbs = [];
+        $results = $this->conn->query('SHOW DATABASES');
+        while ($result = $results->fetch_object()) {
+            $dbs[] = $result->Database;
+        }
+
+        return $dbs;
+    }
+}

src/Service/MysqliConnection.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Service;
+
+use mysqli;
+
+class MysqliConnection
+{
+    private mysqli $connection;
+
+    public function __construct($hostname, $user, $password)
+    {
+        $this->connection = new mysqli($hostname, $user, $password);
+        if ($this->connection->connect_error) {
+            throw new \Exception("Connection failed: " . $this->connection->connect_error);
+        }
+    }
+
+    public function getConnection(): mysqli
+    {
+        return $this->connection;
+    }
+}