Add collector methods for all attributes on objects in an array.

core_extensions.rb

class Array
  def method_missing(method_name, *args, &block)
    if method_name.to_s.is_plural?
      map{ |e| e.send(method_name.to_s.singularize) }
    else
      super
    end
  end

  def respond_to?(method_name, include_private = false)
    method_name.to_s.is_plural? ? true : super
  end
end

class String
  def is_plural?
    pluralize == self
  end
end

Yay! Now I can write User.all.ids instead of the unsightly and awkwardly-typed User.all.map(&:id). So much easier on the pinkies! Also much easier to read.

Any good arguments against doing this?

(Tomorrow, I'll add the class method, so it can be just User.ids. Scandalous!)

1. Have the to_s happen in is_plural? and you'll save yourself a method call.
2. This is probably the Databases job, not Ruby. Especially if it's SQL.
3. Do you not have to pass those parameters to super?
4. Your map could look like this: map(&method_name.singularize.to_sym)` ... I think.

Oh, and make this into a microgem instead.

(Tomorrow, I'll add the class method, so it can be just User.ids. Scandalous!)

You've just described a scope. Well, a poorly named one. You'd have something like this:

class User < ActiveRecord::Base
  scope :ids, order(:id).select(:id)
end

It's probably a brazillion times faster, and also trackable better (because it's in SQL).

Thanks, Kurtis! Great ideas.

1. method_name comes in as a symbol, but I can put is_plural? on the Symbol class to simplify the method_missing check a bit. Seemed more useful on String, but no reason to not have it on both!
2. There are definitely cases where a scope is the better solution. But this also makes some scope-calling/-building easier.
3. I'm not sure, having not mucked with method_missing much, but the examples I found do not seem to need to pass the params on.
4. I'd have to .to_s it first to singularize it. Maybe Symbol#singularize would be a good candidate to include here as well for tidyness.

Rockin. You are right, this is solid microgem territory.

Appreciate the comments!

Yeah, the class version is scope-like, for sure. I'll think about adding scopes based on attribute names. I don't think I come across as many use cases for that, but it sure could be handy in the console when troubleshooting.