# Trying to inject PDO with failing when using type hinting
**URL:** https://discourse.slimframework.com/t/trying-to-inject-pdo-with-failing-when-using-type-hinting/4663
**Category:** Questions
**Created:** [February 18, 2021, 7:14pm UTC](https://discourse.slimframework.com/t/trying-to-inject-pdo-with-failing-when-using-type-hinting/4663 "2021-02-18T19:14:00Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@carlosrpnegrao](https://discourse.slimframework.com/u/carlosrpnegrao)
#### Post date: [February 18, 2021, 7:14pm UTC](https://discourse.slimframework.com/t/trying-to-inject-pdo-with-failing-when-using-type-hinting/4663/1 "2021-02-18T19:14:00Z")
I’ve spent the whole afternoon trying to get DI to work with PDO, but for what’s probably a dumb reason it didn’t work, so, can I ask for a bit of help here?
```php
$builder = new DI\ContainerBuilder();
$builder->addDefinitions([
PDO::class => function (ContainerInterface $container) {
$host = 'localhost';
$dbname = 'xxx';
$username = 'yyyy';
$password = 'zzzz';
$charset = 'utf8mb4';
$flags = [
// Turn off persistent connections
PDO::ATTR_PERSISTENT => false,
// Enable exceptions
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
// Emulate prepared statements
PDO::ATTR_EMULATE_PREPARES => true,
// Set default fetch mode to array
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
// Set character set
PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci'
];
$dsn = "mysql:host=$host;dbname=$dbname;charset=$charset";
return new PDO($dsn, $username, $password, $flags);
},
]);
$container = $builder->build();
AppFactory::setContainer($container);
```
So far this works if I use
```auto
die(var_dump(DPO::class));
```
I can see that a PDO object has been created.
But when it come to the time to use it on a constructor:
```php
abstract class Controller
{
private $db = null;
public function __construct(PDO $db)
{
$this->db = $db;
}
}
```
I get the error:
`Entry "PDO" cannot be resolved: Parameter $dsn of __construct() has no value defined or guessable`
What could I be doing wrong?
---
### Author:  [@odan](https://discourse.slimframework.com/u/odan)
#### Post date: [February 19, 2021, 1:02pm UTC](https://discourse.slimframework.com/t/trying-to-inject-pdo-with-failing-when-using-type-hinting/4663/2 "2021-02-19T13:02:34Z")
I wonder why this line works for you:
> [@carlosrpnegrao](#):
>
> `die(var_dump(DPO::class)); `
This line gives me: `string(3) "DPO"`, but the output must be `object(PDO)#1 (0) {}`
> Entry “PDO” cannot be resolved: Parameter $dsn of \_\_construct() has no value defined or guessable
This error message says that the DI container could not find a container definition and tried to create it manually. So make sure that the DI container for `DPO::class` is correctly configured.
Example:
```php
use DI\ContainerBuilder;
use Slim\App;
use Slim\Factory\AppFactory;
$containerBuilder = new ContainerBuilder();
// Add container definitions
$containerBuilder->addDefinitions( /* ... */ );
// Build PHP-DI Container instance
$container = $containerBuilder->build();
// Create App instance
$app = $container->get(App::class);
// ...
$app->run();
```
Also make sure to set the correct container instance into the Slim AppFactory.
I would also recommend putting the `App::class` into the DI container:
```php
App::class => function (ContainerInterface $container) {
AppFactory::setContainer($container);
return AppFactory::create();
},
```
---
### Author:  [@carlosrpnegrao](https://discourse.slimframework.com/u/carlosrpnegrao)
#### Post date: [February 19, 2021, 1:44pm UTC](https://discourse.slimframework.com/t/trying-to-inject-pdo-with-failing-when-using-type-hinting/4663/3 "2021-02-19T13:44:50Z")
Here’s the configuration for the container:
> [@](#):
>
> > use Psr\Container\ContainerInterface;
> >
> > use Slim\App;
> >
> > use Slim\Factory\AppFactory;
> >
> > use Slim\Middleware\ErrorMiddleware;
> >
> > use Slim\Views\Twig;
> >
> > use Slim\Views\TwigMiddleware;
> >
> > return [
> >
> > ```
> > 'settings' => function () {
> >
> > return require __DIR__. '/config.php';
> >
> > },
> >
> > PDO::class => function (ContainerInterface $container) {
> >
> > $settings = $container->get('settings')['db'];
> >
> > $host = $settings['host'];
> >
> > $dbname = $settings['database'];
> >
> > $username = $settings['username'];
> >
> > $password = $settings['password'];
> >
> > $charset = $settings['charset'];
> >
> > $flags = $settings['flags'];
> >
> > $dsn = "mysql:host=$host;dbname=$dbname;charset=$charset";
> >
> > return new PDO($dsn, $username, $password, $flags);
> >
> > },
> >
> > Slim\Views\Twig::class => function(ContainerInterface $container) {
> >
> > return Twig::create('/home/fmo/slim_fmo/templates', ['cache' => '/tmp/slim_fmo/cache']);
> >
> > },
> >
> > App::class => function (ContainerInterface $container) {
> >
> > AppFactory::setContainer($container);
> >
> > return AppFactory::create();
> >
> > },
> >
> > ```
> >
> > ];
Here I attempt to create the app:
> [@](#):
>
> // Create Container
>
> $containerBuilder = new DI\ContainerBuilder();
>
> // Add container definitions
>
> $containerBuilder-\>addDefinitions( **DIR**. ‘/…/config/container.php’);
>
> // Build PHP-DI Container instance
>
> $container = $containerBuilder-\>build();
>
> // Create App instance
>
> $app = $container-\>get(App::class);
Now it fails with
> [@](#):
>
> FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught DI\NotFoundException: No entry or class found for ‘App’ …
Before I had been using
> [@](#):
>
> AppFactory::setContainer($container);
> $app = \DI\Bridge\Slim\Bridge::create();
so it failed once later, but I figured I’d better try to follow your example as closely as possible.
---
### Author:  [@carlosrpnegrao](https://discourse.slimframework.com/u/carlosrpnegrao)
#### Post date: [February 19, 2021, 2:37pm UTC](https://discourse.slimframework.com/t/trying-to-inject-pdo-with-failing-when-using-type-hinting/4663/4 "2021-02-19T14:37:04Z")
I think I may be stupid.
I used “$app = \DI\Bridge\Slim\Bridge::create();” since I saw it as being the recomended way to initialize the app after installing the PHP-DI Slim bridge, but I never noticed I didn’t pass it the container.
Using “$app = \DI\Bridge\Slim\Bridge::create($container);” solved the problem.