Multiple JoinColumns in Symfony2 using Doctrine annotations?

Question

Here is the problem: Class `Routing` with attributes `objectId` and `objectType`. `objectId` is an int, and `objectType` is a string. The reason for this was to allow the same table to hold data for different kind of routings. For instance for the routing of `Products`, `Department` and `Brand`. So, the combination of the `objectType` and the `objectId` is my JoinColumn. How do I create such a bidirectional relationship with Doctrine2? I looked at inherited relationships, but none of the concepts seemed to be what I'm looking for. I could create some views in the database and just have a couple of different Routing entities, but this does not seem the best route. Here are my entities `Department`, `Product` and `Brand`. `../Entity/Department.php` ``` use Doctrine\ORM\Mapping as ORM; /** * @ORM\Entity() * @ORM\Table(name="departments") */ class Department implements DescribableInterface { /** * @ORM\Id * @ORM\Column(name="id", type="integer", length=11) * @ORM\GeneratedValue(strategy="…

Accepted Answer

After further researching I found a man (Dirk Olbertz) in the know who had the same problem.

Information can be found at: Google Groups: Multiple JoinColumns?

I have now implemented this and I will explain how I did it incase it might help anyone else.

The answer to my problem was the use of single table inheritance.

The first thing I needed to do was update the `routing` entity to use single table inheritance:

`../Entity/Routing.php`

```
/**
 * @ORM\Entity
 * @ORM\InheritanceType("SINGLE_TABLE")
 * @ORM\DiscriminatorColumn(name="object_type", type="string")
 * @ORM\DiscriminatorMap({"product" = "ProductRouting", "department" = "DepartmentRouting", "brand" = "BrandRouting"})
 * @ORM\Table(name="routing")
 */
class Routing
{
    /**
     * @ORM\Id
     * @ORM\Column(name="id", type="integer", length=11)
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;
...
```

The `DiscriminatorColumn` allowed me to specify what column would be used to link, which in this case was the `object_type` field.

The `DiscriminatorMap` allowed me to specify what `object_type` will link with what entities.

These entities then had to be created that extended the `Routing` entity.

`../Entity/ProductRouting.php`

```
/**
 * @ORM\Entity
 */
class ProductRouting extends Routing
{
    /**
     * @ORM\ManyToOne(targetEntity="Product")
     * @ORM\JoinColumn(name="object_id", referencedColumnName="id")
     */
    protected $product;
...
```

`../Entity/DepartmentRouting.php`

```
/**
 * @ORM\Entity
 */
class DepartmentRouting extends Routing
{
    /**
     * @ORM\ManyToOne(targetEntity="Department")
     * @ORM\JoinColumn(name="object_id", referencedColumnName="id")
     */
    protected $department;
...
```

`../Entity/BrandRouting.php`

```
/**
 * @ORM\Entity
 */
class BrandRouting extends Routing
{
    /**
     * @ORM\ManyToOne(targetEntity="Brand")
     * @ORM\JoinColumn(name="object_id", referencedColumnName="id")
     */
    protected $brand;
...
```

Then in each of the `Product`, `Department` and `Brand` entities I needed to add the new `$routings`.

`../Entity/Product.php`

```
...
class Product
{
    ...
    /**
     * @ORM\OneToMany(targetEntity="ProductRouting", mappedBy="product", cascade={"all"})
     */
    private $routings;
...
```

`../Entity/Department.php`

```
...
class Department
{
    ...
    /**
     * @ORM\OneToMany(targetEntity="DepartmentRouting", mappedBy="department", cascade={"all"})
     */
    private $routings;
...
```

`../Entity/Brand.php`

```
...
class Brand
{
    ...
    /**
     * @ORM\OneToMany(targetEntity="BrandRouting", mappedBy="brand", cascade={"all"})
     */
    private $routings;
...
```

Hope that helps...

Multiple JoinColumns in Symfony2 using Doctrine annotations?

Solution

Problem