How to implement many-to-many relationships in Sonata Media Bundle

I had the same problem as you, but I've figured it out.

First of all, you might want to choose for a one-to-many/many-to-one relationship (using an intermediate entity) instead of a many-to-many relationship. Why? Because this allows for additional columns, such as a position column. This way you can reorder the images any way you want. In a many-to-many relationship, the link table only has two columns: the id's of the associated tables.

From the Doctrine documentation:

(...) frequently you want to associate additional attributes with an association, in which case you introduce an association class. Consequently, the direct many-to-many association disappears and is replaced by one-to-many/many-to-one associations between the 3 participating classes.

So I added this to my Product mapping file: (as you can see I'm using YAML as my configuration file format)

oneToMany:    images:        targetEntity: MyBundle\Entity\ProductImage        mappedBy: product        orderBy:            position: ASC

And I created a new ProductImage mapping file:

MyBundle\Entity\ProductImage:    type: entity    table: product_images    id:        id:            type: integer            generator: { strategy: AUTO }    fields:        position:            type: integer    manyToOne:        product:            targetEntity: MyBundle\Entity\Product            inversedBy: images        image:            targetEntity: Application\Sonata\MediaBundle\Entity\Media

Using the command line (php app/console doctrine:generate:entities MyBundle) I created / updated the corresponding entities (Product and ProductImage).

Next, I created/updated the Admin classes. ProductAdmin.php:

class ProductAdmin extends Admin{    protected function configureFormFields(FormMapper $formMapper)    {        $formMapper            // define other form fields            ->add('images', 'sonata_type_collection', array(                'required' => false            ), array(                'edit' => 'inline',                'inline' => 'table',                'sortable'  => 'position',            ))        ;    }

ProductImageAdmin.php:

class ProductImageAdmin extends Admin{    protected function configureFormFields(FormMapper $formMapper)    {        $formMapper            ->add('image', 'sonata_type_model_list', array(                'required' => false            ), array(                'link_parameters' => array(                    'context' => 'product_image'                )            ))            ->add('position', 'hidden')        ;    }

Don't forget to add both of them as services. If you don't want a link to the ProductImage form to be displayed on the dashboard, add the show_in_dashboard: false tag. (how you do this depends on the configuration format (yaml/xml/php) you use)

After this I had the admin form working correctly, however I still had some problems trying to save products. I had to perform the following steps in order to fix all problems:

First, I had to configure cascade persist operations for the Product entity. Again, how to do this depends on your configuration format. I'm using yaml, so in the images one-to-many relationship, I added the cascade property:

oneToMany:    images:        targetEntity: MyBundle\Entity\ProductImage        mappedBy: product        orderBy:            position: ASC        cascade: ["persist"]

That got it working (or so I thought), but I noticed that the product_id in the database was set to NULL. I solved this by adding prePersist() and preUpdate() methods to the ProductAdmin class:

public function prePersist($object){    foreach ($object->getImages() as $image) {        $image->setProduct($object);    }}public function preUpdate($object){    foreach ($object->getImages() as $image) {        $image->setProduct($object);    }}

... and added a single line to the addImages() method of the Product entity:

public function addImage(\MyBundle\Entity\ProductImage $images){    $images->setProduct($this);    $this->images[] = $images;    return $this;}

This worked for me, now I can add, change, reorder, delete, etc. images to/from my Products.

You need to rely on MediaBundle Gallery. In your entity you something like :

/** * @ORM\ManyToOne(targetEntity="Application\Sonata\MediaBundle\Entity\Gallery") * @ORM\JoinColumn(name="image", referencedColumnName="id") */private $images;

And then in your form, you'll be able to link a Gallery to your object with something like :

->add('images', 'sonata_type_model_list', array('required' => false), array('link_parameters' => array('context' => $context)))