Merging hashes with values having the same key getting appended

Question

I wanted to know what would be the best way to achieve this:

my_hash_1 = { fruits: { red: 'apple' }, vegetables: { green: 'spinach' } }

my_hash_2 = { fruits: { green: 'grapes' } }

expected_output = { fruits: { red: 'apple', green: 'grapes' }, vegetables: { green: 'spinach' } }

I have looked into using merge! but that gives me with output:

{:fruits=>{:green=>"grapes"}, :vegetables=>{:green=>"spinach"}}

Answer 1

my_hash_1 = { fruits: { red: 'apple' }, vegetables: { green: 'spinach' } }
my_hash_2 = { fruits: { green: 'grapes' } }
my_hash_3 = { fruits: { yellow: 'mango' },spice: { red: 'chilli' }}

# extended method (multiple hash)
def merge_hash(arr_of_hash)
    result = {}
    arr_of_hash.each do |_hash|
        _hash.each{ |k,v| result[k].nil? ? result[k] = v : result[k].merge!(v) }
    end
    result
end
puts merge_hash([my_hash_1,my_hash_2,my_hash_3])
# {:fruits=>{:red=>"apple", :green=>"grapes", :yellow=>"mango"}, :vegetables=>{:green=>"spinach"}, :spice=>{:red=>"chilli"}}

Answer 2

merge isn't recursive, so it only merges the fruits and vegetables items in the two hashes with its default behaviour. You need to provide a block to merge! to go down to the next level hash and merge them with the default merge too.

my_hash_1 = { fruits: { red: 'apple' }, vegetables: { green: 'spinach' } }
my_hash_2 = { fruits: { green: 'grapes' } }

expected_output = my_hash_1.merge(my_hash_2) { |_, h1, h2| h1.merge(h2) }

p expected_output

Result

{:fruits=>{:red=>"apple", :green=>"grapes"}, :vegetables=>{:green=>"spinach"}}

Answer 3

The two answers do solve what I was trying to do but since I was working with only two hashes and knew what keys to merge, I ended up doing something like this which I found was a simpler approach.

my_hash_1 = { fruits: { red: 'apple' }, vegetables: { green: 'spinach' } }

my_hash_2 = { fruits: { green: 'grapes' } }

my_hash_1[:fruits]&.merge!(my_hash_2[:fruits]) unless my_hash_2[:fruits].nil?

which would essentially merge the two in place in my_hash_1.