Ruby: merge nested hash

Question

I would like to merge a nested hash.

a = {:book=>
    [{:title=>\"Hamlet\",
      :author=>\"William Shakespeare\"
      }]}

b = {:book=>
    [{         


        

Answer 1

A little late to answer your question, but I wrote a fairly rich deep merge utility awhile back that is now maintained by Daniel Deleo on Github: https://github.com/danielsdeleo/deep_merge

It will merge your arrays exactly as you want. From the first example in the docs:

So if you have two hashes like this:

   source = {:x => [1,2,3], :y => 2}
   dest =   {:x => [4,5,'6'], :y => [7,8,9]}
   dest.deep_merge!(source)
   Results: {:x => [1,2,3,4,5,'6'], :y => 2}

It won't merge :y (because int and array aren't considered mergeable) - using the bang (!) syntax causes the source to overwrite.. Using the non-bang method will leave dest's internal values alone when an unmergeable entity is found. It will add the arrays contained in :x together because it knows how to merge arrays. It handles arbitrarily deep merging of hashes containing whatever data structures.

Lots more docs on Daniel's github repo now..