Magento2 : Filtering product list by extension attribute

Question

I added a new extension attribute extensionattribute1 to

Magento\Catalog\Api\Data\ProductInterface.

<attribute code="extensionattribute1" type="string">
  <join reference_table="training_extensionattributes_values" reference_field="product_id" join_on_field="entity_id">
    <field column="extensionattribute1">extensionattribute1</field>
  </join>
</attribute>

That worked all right and the extension attribute is shining up in the collection gathered over the rest api.

Now I would like to filter the product list returned by

Magento\Catalog\Api\ProductRepositoryInterface

programmatically via the SearchCriteriaBuilder (without passing the params via rest api). In concrete: I want to return it all products where extensionattribute1 is set to the value '20'.

What I tried was to build a filter like that:

   $filter=$this->filterBuilder
        ->setField('extensionattribute1')
        ->setValue('20')
        ->create();

But that did not work (Invalid attribute name Error). Same with

   $filter=$this->filterBuilder
        ->setField('extension_attributes[extensionattribute1]')
        ->setValue('20')
        ->create();

Thanks for giving me a hint on how to reach my goal.

Answer 1

this method you used was fine as below:

$filter=$this->filterBuilder
        ->setField('extensionattribute1')
        ->setValue('20')
        ->create();

the change that I found to make the filter working was to add a filterProcessor so that you can declare the extension attribute filter as a custom filter

in the di.xml, declaring a virtual type does exactly this:

<virtualType name="Magento\Eav\Model\Api\SearchCriteria\CollectionProcessor\FilterProcessor" type="Magento\Framework\Api\SearchCriteria\CollectionProcessor\FilterProcessor">
            <arguments>
                <argument name="customFilters" xsi:type="array">
                    <item name="training_extensionattributes_values" xsi:type="object">Mbs\ProductExtensionAttributes\Model\Api\SearchCriteria\CollectionProcessor\FilterProcessor\TrainingExtensionattributesValuesFilter</item>
                </argument>
            </arguments>
    </virtualType> 

finally the filter code below does the filter for my situation.

class TrainingExtensionattributesValuesFilter implements \Magento\Framework\Api\SearchCriteria\CollectionProcessor\FilterProcessor\CustomFilterInterface
{
    /**
     * @inheritDoc
     */
    public function apply(Filter $filter, AbstractDb $collection)
    {
        $collection->getSelect()->where('extension_attribute_training_extensionattributes_values.extension_value1 like ?', $filter->getValue() . '%');
        return true;
    }
}