Ruby on Rails - How to arrange elements of array in particular order

Question

My array is:

[{:age=>28, :name=>"John", :id=>1}, {:name=>"David", :age=>20, :id=>2}]

Order:

[:id, :name, :age] or ['id', 'name', 'age']

The result should be:

[{:id=>1, :name=>"John", :age=>28}, {:id=>2, :name=>"David", :age=>20}]

P/s: I am using Ruby 1.8.7 and Rails 2.3.5

Thanks

Answer 1

Order doesn't matter when it comes to hashes. You do not need to do that. Trust me.

What you're using is an Hash which, unlike Array doesn't care for positions. You only access the value by it's Symbol or Key .

So, there is no need of doing what you want to.

Answer 2

As others have said, you cannot do that with Ruby 1.87 or prior. Here is one way to do that with Ruby 1.9+:

arr = [{:age=>28, :name=>"John", :id=>1}, {:name=>"David", :age=>20, :id=>2}]
order = [:id, :name, :age]

arr.map { |h| Hash[order.zip(h.values_at(*order))] }
  #=> [{:id=>1, :name=>"John", :age=>28}, {:id=>2, :name=>"David", :age=>20}] 

In Ruby 2.0+, you can write:

arr.map { |h| order.zip(h.values_at(*order)).to_h }

I thought 1.8.7 went out with the steam engine.