Add CollectionIterator::map

[tlode]

Adds array_map helper for CollectionIterator

[chanmix51]

Is it different from using a filter and then extract the iterator ?

$identity = function($row) { return $row; };
$result->registerFilter($identity)->extract();

Would that behave differently thant $result->map($identity); ?

[tlode]

Using a filter and the extract method would only return row values of type array. I would like to use map to easily transform rows or entities in something different, for example value objects.

$valueObjects = $result->map(
   function ($entity) { 
      return new SomeValueObject($entity->getProperty());
   }
);

I have such cases a lot and always have to iterate over the result set externally.

[chanmix51]

Yes but this array is at the end used to hydrate entities by the iterator. This is the way we can turn json fields into embedded objects by example.

[tlode]

Perhaps, I don't understand the purpose of the filter feature. But I think, it is meant for a different use case.

In some cases I don't need to have flexible entities in the end. I wan't to transform the result set into something different, something independent.

Using array_map is a convenient way to achieve that and adding a map function in the CollectionIterator seemed appropriate.

It is another question if it could / should be rather added in the ResultIterator instead. I am not sure.

[chanmix51]

That’s what I felt. If you do not need entities, wouldn’t that be a ConvertedResultIterator method instead ? (I am +1 on this)

[tlode]

No, I do all the queries through Model methods. ConvertedResultIterator wouldn't help, since CollectionIterator extends from ResultIterator.

[chanmix51]

ConvertedResultIterator always return an array per row or can be expanded as an array of arrays. The CollectionIterator does the same but with entities. Would’t the CollectionIterator::map output something else than an array of entities in that case ?

[tlode]

Yes, as mentioned earlier it would return an array of anything you like. In my case simple value objects which I don't treat as entities

[tlode]

Sorry, I shall not write comments with the phone :-)

[chanmix51]

Ok, the feeling I have regarding this is the following: add the map method in the ConvertedResultIterator maybe using a PHP generator. Break the inheritance withCollectionIterator (it was a bad idea) and use the interface developed in pomm-project/Foundation#71 instead. What do you think ?