How to merge multiple hashes in Ruby?

Question

h  = { a: 1 } h2 = { b: 2 } h3 = { c: 3 } 

Hash#merge works for 2 hashes: h.merge(h2)

How to merge 3 hashes?

h.merge(h2).merge(h3) works but is there a better way?

Answer 1

Since Ruby 2.0 on that can be accomplished more graciously:

h.merge **h1, **h2 

And in case of overlapping keys - the latter ones, of course, take precedence:

h  = {} h1 = { a: 1, b: 2 } h2 = { a: 0, c: 3 }  h.merge **h1, **h2 # => {:a=>0, :b=>2, :c=>3}  h.merge **h2, **h1 # => {:a=>1, :c=>3, :b=>2} 

Answer 2

You could do it like this:

h, h2, h3  = { a: 1 }, { b: 2 }, { c: 3 } a  = [h, h2, h3]  p Hash[*a.map(&:to_a).flatten] #= > {:a=>1, :b=>2, :c=>3} 

Edit: This is probably the correct way to do it if you have many hashes:

a.inject{|tot, new| tot.merge(new)} # or just a.inject(&:merge)