# My fantasy: instant array of AR attributes? **URL:** \ **Category:** Rails\ **Created:** [December 23, 2006, 1:58am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277 "2006-12-23T01:58:06Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 1:58am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/1 "2006-12-23T01:58:06Z")
If there’s a way to do this, I would be very happy: let’s pretend that I have an array called folks holding several AR objects from a model called People: folks = [ \ “bob”, sex =\> “m”, age =\> 40\>, \ “sam”, sex =\> “m”, age =\> 7\>, \ “dee”, sex =\> “f”, age =\> 25\> ] What i’ve always wanted to do was say something like: folks.names …and get an array back with [“bob”,“sam”,“dee”]. It seems kind of cumbersome to write a loop to do this, especially when RoR is supposed to be all neato and cool. Am I missing something obvious or do I really have to use a loop? Thanks! – Jason F. - removed\_email\_address@domain.invalid - [http://www.seethroo.us/](http://www.seethroo.us/) work: (310) 601-8454 cell: (415) 254-4890 AIM/Skype: jfrankov ---
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 2:04am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/2 "2006-12-23T02:04:07Z")
You could go about it a number of ways. I like this method folks.collect! { |person| person.name} Now folks is an array of all of their names… On 12/22/06, Jason F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > – seth at subimage interactive [http://www.subimage.com/sublog/](http://www.subimage.com/sublog/) ---
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 2:12am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/3 "2006-12-23T02:12:08Z")
subimage interactive wrote: > You could go about it a number of ways. > > I like this method > > folks.collect! { |person| person.name} Doesn’t Rails provide a shortcut: folks.collect(&:name) ? – Phlip [Redirecting...](http://www.greencheese.us/ZeekLand) ← NOT a blog!!! ---
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 2:24am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/4 "2006-12-23T02:24:09Z")
Hi – On Fri, 22 Dec 2006, Phlip wrote: > folks.collect(&:name) > > ? Yes, and actually the thing that makes it work (Symbol#to\_proc) is in 1.9: $ /usr/local/lib/ruby-cvs/bin/ruby -ve ‘puts [1,2,3].map(&:to\_f)’ ruby 1.9.0 (2006-12-09 patchlevel 0) [i686-linux] 1.0 2.0 3.0 David – Q. What’s a good holiday present for the serious Rails developer? A. RUBY FOR RAILS by David A. Black ([Ruby for Rails](http://www.manning.com/black)) aka The Ruby book for Rails developers! Q. Where can I get Ruby/Rails on-site training, consulting, coaching? A. Ruby Power and Light, LLC ([http://www.rubypal.com](http://www.rubypal.com)) ---
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 2:28am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/5 "2006-12-23T02:28:10Z")
Even shorter: names = folks.collect(&:name) -christos ---
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 2:54am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/6 "2006-12-23T02:54:16Z")
I love it! My fantasy has come true. Anyone got a handle on what the & does? I knew about collect but it alters the original array, which I want to avoid (shuold’ve said that in my first email, sorry). Thanks to everyone for the suggestions! -Jason – Jason F. - removed\_email\_address@domain.invalid work: (310) 601-8454 cell: (415) 254-4890 AIM/Skype: jfrankov ---
**Author:** ![jfoxny](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/a6a055/32.png) [@jfoxny](https://www.ruby-forum.com/u/jfoxny)\ **Post date:** [December 23, 2006, 3:04am UTC](https://www.ruby-forum.com/t/my-fantasy-instant-array-of-ar-attributes/80277/7 "2006-12-23T03:04:17Z")
Hi – On Fri, 22 Dec 2006, Jason F. wrote: > On Dec 22, 2006, at 5:27 PM, Christos Z. wrote: > > > Even shorter: > > > > names = folks.collect(&:name) > > I love it! My fantasy has come true. Anyone got a handle on what the & does? > I knew about collect but it alters the original array, which I want to avoid > (shuold’ve said that in my first email, sorry). collect (aka map) doesn’t alter the original array, unless you use the ! version (collect! or map!). I think one of the people who replied did use that, but Christos’s version doesn’t. The & introduces a lambda (an anonymous function, technically an instance of Proc), to be used as the code block to go with the method call. For example, look at this: array = [1,2,3,4,5] array.map {|e| e \* 10 } # [10,20,30,40,50] and now with a separate lambda: lam = lambda {|e| e \* 10 } array.map &lam # [10,20,30,40,50] The reason it works with &:name is that Rails has a to\_proc conversion method for symbols. That method gets called automatically when the & is applied. When you do &:name, you get a lambda that, if you wrote it out by hand, would look like this: lambda {|e| e.send(:name) } So – the net effect of all of this is that this: folks.collect(&:name) calls collect on folks, with a code block (a lambda) that performs the function of calling the “name” method on each element in folks. The result is a second, result array, consisting of all the names. David – Q. What’s a good holiday present for the serious Rails developer? A. RUBY FOR RAILS by David A. Black ([Ruby for Rails](http://www.manning.com/black)) aka The Ruby book for Rails developers! Q. Where can I get Ruby/Rails on-site training, consulting, coaching? A. Ruby Power and Light, LLC ([http://www.rubypal.com](http://www.rubypal.com))