[DDC-1398] Extra-lazy get for indexed associations

[sandermarechal]

If an association is EXTRA_LAZY and has an indexBy, then
you can call get() without loading the entire collection.

[beberlei]

<3

[stof]

you need to handle the case of non-existent keys properly: the Collection interface wants to get null in such case, not false (which is what current returns when the array is empty)

[stof]

you could also implement containsKey this way, checking if an element is found

[beberlei]

can you test for the actual data being returned as well? in the second test as well

[stof]

and please also add a test for non-existent keys

[sandermarechal]

I think I fixed all the things you pointed out. I'm looking at implementing containsKey as well.

[sandermarechal]

I am not sure what the best way is to handle containsKey. I see three possible options:

1. Simply call get from containsKey and check for NULL. This is simple to implement but it will load the actuall entity (which may have FETCH_EAGER associations, causing more data to be hydrated, etcetera).

2. Query the database directly. This is what I have been working on so far. It works, but looks ugly. There is significant code overlap between containsKey and count and I don't see a non-ugly way to reduce it, except for option 3.

3. Extend the count API to accept additional conditions and/or Criteria. In this case containsKey could simply use count with an extra condition and check if the result >= 0. Downside is that it is more work and that it is an addition to the API. On the upside, this sounds like a nice feature to have. People would be able to do things like this on a collection, and it would work properly on extra lazy collections as well:

   $numUsers = $group->users->count(array('active' => true));
   

So, what do you suggest?

[beberlei]

@sandermarechal Lets keep containsKey for another time, we have something very useful here already. One thing I would like to see is the Persister Collections to use find() instead of findBy() to use the identity map, if the index-by is the identifier field. Otherwise its already awesome

[sandermarechal]

@beberlei: I'm sorry, I don't quite understand what you mean. I'm not using find() in this PR but I am using load() directly.

Do you mean fixing the TODO at BasicEntityPersister->load() on line 742?

[beberlei]

@sandermarechal yes, please use the EntityManager#find instead if index-by == identifier field. This will greatly enhance performance in some use-cases.

[stof]

@sandermarechal regarding your propsal above, I don't think count() should be changed. It is the implementation of Countable

[sandermarechal]

@beberlei Done

@stof Good point. I didn't think about Countable. Anyway, I will make a separate PR for containsKey so this can be merged.

[beberlei]

@sandermarechal i am afraid you need to add more tests now ;) the article stuff uses articleIds, so its never triggering the collection persister get calls anymore

[sandermarechal]

@beberlei Yup. Done.