Ruby Hash with integer keys changed to string keys

Question

I create a hash in ruby with integer keys and send it as a JSON response. This JSON is then parsed and the hash is converted back to ruby. The keys are now string literals.

I get it that JSON doesnt support integer keys but I came upon this method which basically parses the hash so that it has symbol keys.

JSON.parse(hash, {:symbolize_names => true})

Is there a similar function for obtaining back the original integer keys

a = {1 => 2}
a.keys
=> [1]
b = JSON.parse(JSON.generate(a))
b.keys
=> ["1"]

My hash is very complicated. The value itself is a hash which is supposed to have integer keys. There are multiple such levels of nesting

Sure, iterate over the keys, convert them to integers, and set their values to the original string keys' values. — Dave Newton

Martin Martin · Accepted Answer · 2014-08-20T12:58:54

Nothing in JSON as far as I know, but conversion is easy:

json_hash = {"1" => "2" }
integer_hash = Hash[json_hash.map{|k,v|[ k.to_i, v.to_i ]}]
=> {1 => 2}

So, we take all key & value from the initial hash (json_hash), call to_i on them and get them in a new hash (integer_hash).

Even nesting is not blocking. You could do this in a method:

def to_integer_keys(hash)
  keys_values = hash.map do |k,v|
    if(v.kind_of? Hash)
      new_value = to_integer_keys(v) #it's a hash, let's call it again
    else
      new_value = v.to_i #it's a integer, let's convert
    end

    [k.to_i, new_value]
  end

  Hash[keys_values]
end

Ruby Hash with integer keys changed to string keys

1 Answers