Missing target data in Custom Transformer

[cpoint-eu]

It would be great to have access to the target object's data and the specific property being transformed in the transform method of a custom transformer. This would greatly help in creating more generic data transformation rules.

If I have a data field that contains IDs instead of specific objects, and I want to create a generic transformer to translate IDs into objects, I currently have to create a separate transformer for each transformation. The only difference between these transformers is the className, which seems unnecessary to me. If I had access to the target object's data, I could determine this directly within it (similarly to the support method).

[AntipodTX]

Same issue here.

My case:

I map the DTO, containing some references as integer IDs to the Doctrine Entity, containing related entities of the different types - so i want to create a correspondent Entity based on its ID for every DTO/Entity property pair. Now, i have no possibility to determine the target Entity class with this concrete ID.

My proposal:

Give the array|null return type to the supports() method (where we have the full access to the source and the target metadata, null = 'not supported') to have it written in the generated mapper class (and cached) and have it as a fourth parameter of the transform() method (or have a separated method for that purpose with the same input parameters as support() - it will be even better). Using this, the property mappers can be more flexible.

[MrMeshok]

I think you can use TransformerFactory for that, they get all needed metadata. For example something like that

class GenericTransformerFactory
{
    public function getTransformer(TypesMatching $types, SourcePropertyMetadata $source, TargetPropertyMetadata $target, MapperMetadata $mapperMetadata): ?TransformerInterface
    {
        $targetType = $types->getTargetUniqueType($types->getSourceUniqueType());

        return new GenericTransformer($targetType->getClassName());
    }
}

But transformerFactories argument in AutoMapper::create() is deprecated, I am not sure why. And I am not familiar with Symfony, so don't know how to inject custom factories there

[AntipodTX]

@MrMeshok Thank you for your advice!
As i see, it should not be difficult to override the TransformerFactory in Symfony - the automapper bundle already implements a automapper.transformer_factory tag for autowiring. Then it will be possible to use your own PropertyTransformer and add a parameter to the transform() call.