[2.x] Custom data provider

[soyuka]

This issue will lead to a documentation pull-request.

In 2.x, the data provider uses decorations. Actually, the default data provider will call it's decorated data providers and return the according method, or skip silently when a ResourceClassNotSupportedException is thrown.

Based on the CollectionDataProvider, my natural implementation (with symfony) would be to:

1. declare a service

services:
    my_custom.collection_data_provider:
        class: 'Acme\DataProvider\BlogCollectionDataProvider'
        decorates: 'api_platform.doctrine.orm.default.collection_data_provider'
        arguments: 
            - '@doctrine'
            - '@my_custom.collection_data_provider.inner'

1. Have a class that throws a ResourceClassNotSupportedException if the current resource class is not supported:

//skipping the class/constructor declaration which implements the CollectionDataProviderInterface

public function getCollection(string $resourceClass, string $operationName)
{
        if ($resourceClass !== 'Acme\Entity\BlogEntity') {
            throw new ResourceClassNotSupportedException();
        }

        //fetch data
}

What I don't understand, is that if my custom data provider decorates the api_platform.doctrine.orm.default.collection_data_provider, I get something like:

return $this->services['my_custom.collection_data_provider'] = new \Acme\DataProvider\BlogCollectionDataProvider(
  $a, 
  new \ApiPlatform\Core\Bridge\Doctrine\Orm\CollectionDataProvider($a, ...)
);

The default collection data provider will therefore never get any decorations, and my custom data provider will always throw an un-catched ResourceClassNotSupportedException.

Is this a matter of decoration priorities or am I doing something wrong?

Thanks!

[teohhanhui]

Looks like you've figured it out 👍

[soyuka]

Hmm, actually I think I understood how it's supposed to work but I think there's still something wrong.

For example, I added a bunch of dataproviders, all decorating api_platform.collection_data_provider.

In doctrine_orm.xml we're setting up the following services:

        <service id="api_platform.collection_data_provider" alias="api_platform.doctrine.orm.default.collection_data_provider" />
        <service id="api_platform.doctrine.orm.collection_data_provider" public="false" abstract="true">
            <argument type="service" id="doctrine" />
            <argument type="collection"></argument> <!-- extensions -->
        </service>
        <service id="api_platform.doctrine.orm.default.collection_data_provider" parent="api_platform.doctrine.orm.collection_data_provider" class="ApiPlatform\Core\Bridge\Doctrine\Orm\CollectionDataProvider" />

With no decoration on top of the default services, debug:container outputs:

(development ✗)❯ ./bin/console debug:container | grep data_provider
  api_platform.collection_data_provider                                ApiPlatform\Core\Bridge\Doctrine\Orm\CollectionDataProvider

But as soon as I add a decorator:

  api_platform.collection_data_provider                                alias for "core_orm.closure_collection_data_provider" # this is my service, not calling decorators

There, as soon as I throw the ResourceClassNotSupportedException it breaks. I could call the decorators from the custom data provider but it feels weird. Should the Doctrine orm provider not always be the one calling custom decorators instead?

From what I put in the docs, and what I think should be the correct implementation, this isn't working yet.