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Make "first" and "last" on associations accept conditions (etc)

#275

Just noticed that while you can do stuff like this:

Topic.first :conditions => { :foo => bar }

Trying the same type of thing across an association won't work:

topic.users.first :order => 'created_at'
topic.users.last :conditions => { :bar => baz }
topic.users.last :condtions => 'abc > 1'

All of those produce an exception:

TypeError: can't convert Hash into Integer

So evidently the proxy being returned by the association is Array-like (not sure of the internal implementation details, if it's an Array subclass, an Array extended with a module or something else), and the methods getting called are actually Array#first and Array#last, which take a single integer argument.

Not sure if this is a bug or merely a missing feature. I won't have time to dig into this myself for a while yet, but I wanted to get it into the tracker anyway so that it won't get forgotten.

Any comments on what the best solution would be? My guess is that we should alias the Array#first and Array#last methods, pass through to them if we get a single integer argument otherwise if we get a hash then do the standard ActiveRecord thing on them. What do people think?

Reported by Wincent Colaiuta · May 29th, 2008 @ 06:16 PM

Activity

Amos King
Maybe I'm missing something, but I put this test in my branch:
def test_first_on_association_with_conditions
firm = Firm.new("name" => "A New Firm, Inc")
firm.save
client = Client.new("name" => "TheClient.com", "firm_id" => firm.id)
client.save
client2 = Client.new("name" => "TheClient2.com", "firm_id" => firm.id)
client2.save
assert (firm.clients.first :conditions => { :name => 'TheClient2.com' }) == client2
end
and everything is passing just fine.

May 29th, 2008 @ 10:14 PM
Amos King
- 0001-tests-for-associations-first-and-last-methods-being.patch 1.58 KB
May 29th, 2008 @ 11:07 PM
Amos King
Here is a patch that has passing tests to do the same thing. I don't think this a bug.

May 30th, 2008 @ 11:49 AM

Wincent Colaiuta

Perhaps it depends on the type of the association and the options specified? I can reproduce this with a number of different models in my codebase. One example:

$ script/console
Loading development environment (Rails 2.0.991)
>> user = User.first
=> #<User id: 7921, display_name: "Wincent Colaiuta", passphrase_hash: "f2833a7d3dcd18b9c3c6379d461ad96586c5fb547c1c3dea6b2...", passphrase_salt: "1u1CfzMOxH4Jzguk", superuser: true, verified: true, suspended: false, session_key: "XHY8AUi08bjyxSpOkIvZ0eEE7ElWJOBg", session_expiry: "2008-04-18 20:54:50", deleted_at: nil, created_at: "2008-04-11 20:53:08", updated_at: "2008-04-11 20:54:50", comments_count: 4348, topics_count: 6>
>> user.emails
=> [#<Email id: 6817, user_id: 7921, address: "win@wincent.org", default: true, verified: true, created_at: "2008-04-11 20:53:08", updated_at: "2008-04-11 20:53:08", deleted_at: nil>]
>> user.emails.class
=> Array
>> user.emails.first
=> #<Email id: 6817, user_id: 7921, address: "win@wincent.org", default: true, verified: true, created_at: "2008-04-11 20:53:08", updated_at: "2008-04-11 20:53:08", deleted_at: nil>
>> user.emails.first :conditions => { :default => false }
TypeError: can't convert Hash into Integer
	from /Users/wincent/trabajo/unversioned/wincent.com/src/vendor/rails/activerecord/lib/active_record/associations/association_proxy.rb:177:in `first'
	from /Users/wincent/trabajo/unversioned/wincent.com/src/vendor/rails/activerecord/lib/active_record/associations/association_proxy.rb:177:in `send'
	from /Users/wincent/trabajo/unversioned/wincent.com/src/vendor/rails/activerecord/lib/active_record/associations/association_proxy.rb:177:in `method_missing'
	from /Users/wincent/trabajo/unversioned/wincent.com/src/vendor/rails/activerecord/lib/active_record/associations/association_collection.rb:250:in `method_missing'
	from (irb):5
>> user.emails.first(1)
=> [#<Email id: 6817, user_id: 7921, address: "win@wincent.org", default: true, verified: true, created_at: "2008-04-11 20:53:08", updated_at: "2008-04-11 20:53:08", deleted_at: nil>]

Will see if I can come up with a reduced test case.

May 30th, 2008 @ 11:08 AM

Wincent Colaiuta
Looks like this might be fixed by commit 73c5963 (which is post-RC1).

May 30th, 2008 @ 11:31 AM
Pratik
- State changed from new to invalid
May 30th, 2008 @ 11:49 AM