Symfony 2最佳实践DBAL没有对象原则

Question

Well I am finally started to learn Symfony and I think peoples will understand my question (I Hope) and my wish to structure my code...

Well, I would like to create a Class which is called Reception and this class has a sql let's say in each methods/function. Each and evry methods can return a different nombre of column results.

Example : Sql 1 : Jo;DATE; Sql 2 : Client;Car;Time

Let's tell that I don't want to create a Entity to use it with doctrine...

I would like to use DBAL (pdo doctrine sql query) to do execute my queries... like in normal PHP poo programming.

Finally the question is : wether I should do this class as a Service, Entity? or I can simple put the pdo query in the controller....

Thanks in advance for your answers... I avoid doctrine for the moment because I principaly doing some statistiques and also to play a bit with symfony and to increase the difficutly level progresivly...

thanks for your understanding... Good Day

Answer 1

A Service ( docs ) is usually just a class which is responsible for doing some specific task. Lets say you have some statistics you need to be updated whenever specific events occur (ie file is downloaded, favored, etc) and you have multiple controllers where those different events occur. It would be a really bad idea to simply "copy-paste" your code. A better way would be to create a service and call it.

An Entity ( docs ) is an object which represents your database table. This object can later be used to generate forms in Symfony. Once you create an Entity , you can then create an EntityRepository . It is used to store more comprehensive sql queries. You can, for instance, have a method like this:

public function findUsersWithOrders() {
    // Here you can:
    //  1. use queryBuilder, which generates the query for you
    //  2. write your DQL (Doctrine Query Language) manually
    //  3. write a plain SQL query and return the results
}

I would strongly advice you to use this approach - it will save you a lot of time once you get a hold of it and IMHO is a better coding practice.

If you still decide you would want to pursuit your idea of storing queries in a class:

1. Yes, you could create a Service and use it for that purpose. You should use Symfony >= 2.3 because of Lazy Services which optimizes service loading. Here is an example of how your service might look like:

    // App\\BaseBundle\\Services\\MyServiceName.php namespace App\\BaseBundle\\Services; use Doctrine\\ORM\\EntityManager; class MyServiceName { /** * @var \\Doctrine\\ORM\\EntityManager */ private $em; /** * @var \\Doctrine\\DBAL\\Connection */ private $connection; public function __construct(EntityManager $entityManager) { $this->em = $entityManager; $this->connection = $entityManager->getConnection(); } public function getUsers(){ // Update query $this->connection->query('UPDATE statistics SET counter=counter+1 WHERE id = 1')->execute(); // Prepare (you can use just query() as well) $select = $this->connection->prepare('SELECT * FROM users WHERE username LIKE :username'); $select->bindValue(':username', '%sample%'); $select->execute(); return $select->fetch(\\PDO::FETCH_ASSOC); } } 

   Then, in your services.yml file you need to put this:

    app.myservicename: class: App\\BaseBundle\\Services\\MyServiceName arguments: [ @doctrine.orm.entity_manager ] 

   Now, whenever you call $this->get('app.myservicename') from a Controller , you will get an instance of your class.

2. Of course, you can put your sql code in the controller as well. This is not a good practice and you should avoid doing it, though. This example shows you how to do it:

    /** * @Route("/some/route") * @Template() */ public function indexAction() { /** * @var \\Doctrine\\ORM\\EntityManager $em */ $em = $this->getDoctrine()->getManager(); // some business logic ... try { $em->getConnection()->query('UPDATE statistics SET counter=counter+1 WHERE id = 1')->execute(); } catch(\\Doctrine\\DBAL\\DBALException $e){ // the query might fail, catch the exception and do something with it. } // other business logic... return array('name' => 'Hello World'); } 

I would advice you to have a look at the symfony best practices to see what are the best approaches to common problems. Also reading the main documentation will help you clear a lot of questions.