#401 ✓resolved
Troy K

extlib LazyArray to_json proxy

Reported by Troy K | June 18th, 2008 @ 02:57 PM

I'm not sure if this is something you want to support, but I'm mentioning it because json encoding model/resource collections is important in my small corner of the world, and it should at least be noted in the documentation that Resource.all() returns a DataMapper::Collection < LazyArray and although it smells like an Array, you need to add your own proxy for something like to_json

LazyArray will not proxy the method "to_json" to the underlying array, because the JSON library auto-adds "to_json" to every object, so method_missing is never called. The fix is simple:

class LazyArray
  def to_json(*a)

We do this when we initialize our framework, which is where I'm tempted to say it belongs -- but just wanted you guys to be aware as I'm sure it will raise a few wtf's if not documented, especially in Rails apps migrating to dm where render :json just works with AR collections.

Comments and changes to this ticket

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) June 18th, 2008 @ 04:23 PM

    • Milestone cleared.

    I think it's sort of a slippery slope trying to override cases like this, there will always be modules like json that shove stuff into the namespace that we have to override.

    However, I would accept a patch to LazyArray that makes it act more like a "Blank Slate" proxy, and uses undef_method to remove all but a few essential methods, and delegates everything else down to the underlying Array. See how we've done this in the OneToMany::Proxy class for example.

  • Troy K

    Troy K June 19th, 2008 @ 01:39 AM

    Ok, I'll take a look at OneToMany::Proxy and submit a patch for your review.

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) November 28th, 2008 @ 02:39 AM

    • Assigned user changed from “Sam Smoot” to “Dan Kubb (dkubb)”
    • State changed from “new” to “open”

    Troy, is this still an issue?

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) November 30th, 2008 @ 06:50 PM

    • Assigned user changed from “Dan Kubb (dkubb)” to “Xavier Shay”

    Xavier, I've emailed Troy about this too, but I wanted to follow up with you to see if you think this is still applicable.

  • Xavier Shay

    Xavier Shay November 30th, 2008 @ 06:59 PM

    • Tag changed from suggestion to dm-serializer, extlib, lazyarray
    • State changed from “open” to “resolved”

    Collections implement #to_json, so it should never get down to LazyArray to proxy the call.

    There was a related problem with the collection proxies - we had to undef #to_json so it was passed through to the collection correctly.

    This could still be a potential issue if LazyArray is used for anything that isn't a DM::Collection? If that is the case, I recommend using the same approach as used for the other proxies - undef the method in the lib that depends on the method being proxied (dm-serializer).

  • Dan Kubb (dkubb)

    Dan Kubb (dkubb) November 30th, 2008 @ 07:52 PM

    Yeah, I'll look into it. I would like LazyArray to be useful for more than just Collection (although offhand I can't think of anything I'd use it for)

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