Rails 2.X ad Rails 3的“范围”方法

Question

I've got a plugin I'm using for websites using Rails 2.X or Rails 3.

In Rails 2.3, I used a lot the 'scoped' method for complex queries :

p = Person.scoped({})
p = p.active
p = p.with_premium_plan if xyz
p
etc.

But I saw that it changed in Rails 3 :

p = Person.scoped
etc.

So is it normal that I have to do something like that in my plugin (to be able to run it in both version of Rails), or can you suggest something nicer?

if Rails.version.split(".")[0] == "3"
  p = Person.scoped
else
  p = Person.scoped({})
end

Thanks! Vince

Answer 1

I'd really stay away from checking the literal version of Rails. You're just setting yourself up for failure when Rails 4 comes out.

If you're curious if a method takes a parameter or not, use this:

p = (Person.method(:scoped).arity == 1) ? Person.scoped({ }) : Person.scoped

The arity method on a class or module returns the number of parameters required, or a negative value if it's a somewhat arbitrary number as is the case when some are optional.

That being said, in Rails 2.3.8 it doesn't seem you need to pass any parameter to scoped anyway.