load_collection? triggers sql query on inherited resources

[tmikoss]

When resource_base is a ActiveRecord::Associations::CollectionProxy (common case - inherited resources) resource_base.respond_to? will actually execute the query, due to it being overwritten here.

This presents a problem when working with big data sets + pagination, since all the records will be loaded in memory regardless of how the collection is paginated afterwards.

Rails version: 3.2.11
CanCan version: 1.6.8

[tmikoss]

Will need some version-dependent guards around this code, since the referenced code is different prior to 3.1, and has changed again in current master.

[tmikoss]

This should fix #398

[natebird]

Can you write up a pull request for the different versions of Rails? Then Ryan can nail down a fix for various versions and decide CanCan v.x will support which implementations or if we can to handle the version cases inline.

[matt-glover]

Does this need to be something like: if @options[:through] && parent_resource instead to avoid raising when resource_base resolves to the resource_class when @options[:shallow] is true?

[pdf]

I like the end.method syntax better here because it avoids duplication, but I think simply checking for resource_base.respond_to? :proxy_association as I did in #729 is the right way of fixing this. I've been using that in production for about a year.