Rails: How to reivent the wheel

Today, I saw the following code snippet in some source code:

def group_by_attribute1(items)
  array = items.map { |i| [i.attribute1, i] }
  array.inject(Hash.new{ |h,k| h[k]=[] }) do |h(k,v)|
    h[k] << v
    h
  end
end

Aaaaaah… MASTE PEESE!

Of course, there is no need to explain why that’s so wrong. That’s why the wheel shouldn’t be reinvented. Best of all, this code passed all quality checks of its repository.

I think that’s why group_by was invented:

def group_by_attribute1(items)
  items.group_by(&:attribute1)
end

See? Much easier and cleaner.