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

Question

I am trying to relate SonataMediaBundle to another Entity: Products with a relation ManyToMany.

The schema and relation are well created.

However, when I edit or create a new product, I try to add a button where I can search a media file through the media library and a button to upload a new file.

For a relation OneToMany, this is easily done in Admin\ProductAdmin::configureFormFields by adding:

->add('image', 'sonata_type_model_list', array(
                    'required' => false
                ), array(
                    'link_parameters' => array(
                        'context'  => 'default',
                        'provider' => 'sonata.media.provider.image'
                     )
                ))

So I get the same 3 icons as they already been used in the Gallery of SonataMediaBundle (add from library, upload and delete)

BUT on the relation ManyToMany it isn't possible! Because every time I choose a media, it replaces the previous one. So I can't select multiple media types.

I thought on using the same way as The Gallery (galleryHasMedia)

->add('galleryHasMedias', 'sonata_type_collection', array(
            'by_reference' => false
        ), array(
            'edit'     => 'inline',
            'inline'   => 'table',
            'sortable' => 'position',
            'link_parameters' => array('context' => $context)
        ))

However, it is really complex. How can I choose or upload multiple media files on another Entity through a ManyToMany Relation?

Answer 1

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.