Getting associated entries in Doctrine 2

Question

I've decided that it would be a good asset to get familiar with an ORM and went for Doctrine 2 as the ORM of choice.

I'm working on a test project to learn the basics of Doctrine. Although most people usually go with a blog, I've decided to make a basic app in which you can save and track orders. My database schema would be as follows:

User
    id
    name
Product
    id
    name
    price
Sales_order
    id
    user_id
    product_id
    quantity
    unit_price

Hence, my Order model looks like:

/**
 * @Entity
 * @Table(name="sales_order")
 */
class Order {

    /**
     * @Id
     * @Column(type="integer", nullable=false)
     * @GeneratedValue(strategy="AUTO")
     */
    private $Id;

    /**
     * @OneToOne(targetEntity="User", inversedBy="user")
     */
    private $user;

    /**
     * @OneToOne(targetEntity="Product", inversedBy="product")
     */
    private $product;

    /**
     * @Column(type="integer", nullable=false)
     */
    private $quantity;
}

Now, the question is, is there a simple way of accessing all the orders from the user model? Should I write DQL (doctrine query language) for these kind of basic stuff or is there a way to easily get associated entities? I mean, there wouldn't be any point to this otherwise, right? Also, am I doing these associations correctly? I'm really confused in this very basic model... Detailed help is really appreciated. Thank you.

Answer 1

Firstly, don't worry too much about the database design. You should design your entities and use the SchemaTool.

Now, the question is, is there a simple way of accessing all the orders from the user model?

Do you mean access all of the orders from the user model, or access all the orders associated to a user?

If you meant the former, well you are doing things wrong (see below). If you meant the later, you should setup a bi-directional relationship between orders and users. (BTW, it would be OneToMany not OneToOne as one user would likely have many orders).

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I'm really confused in this very basic model...

I think what you having trouble with - along with many PHP programmers - is the fundamental understandings of the DataMapper pattern and ultimately Domain Driven Design as well. Remember, you are dealing with persistable objects, not database tables.

I cannot provide detailed information here because I'd be writing a book, hence this I would recommend you get a book on Domain Driven Design to help kick start with the principles. There are a few good online resources available, like a series of blog posts by Federico Cargnelutti, however they aren't specific to Doctrine 2.