Parse JSON in Rails app that is camelCase

Question

I am writing back-end to one app and my front-end developer forced me to use small-cap camelCase notation in JSON files that he is receiving (sic!). With sending him this is no problem because I use Jbuilder and there is an option to provide such possibility. But how can I parse his responses in simple way? Is there any option to make it automatically instead rewriting all keys using ActiveSupport String#underscore method?

Example:
I get request with JSON:

{
  'someValue': 324,
  'someOtherValue': 'trolololololo'
}

And in Rails land I want use it as follows:

@data = JSON.parse(request.body)
@some_value = @data['some_value'] # or @data[:some_value]

would you provide an example? If it's a class name like userPermission we can help. but really, this is a severe antipattern. Note that front end framework ember will use camelCase in javascript land, but translate that to camelCase in Rails land. — Jesse Wolgamott, Feb 19 '13 at 13:45
It's not about class names. It's about JSON fields names. I want to have Rails land as is (with snake_case) and JS land as is (with camelCase). — Hauleth, Feb 19 '13 at 15:15

score 2 · Accepted Answer · edited May 23 '17 at 12:16

I found some code here so I post it again for you so it is easy to copy.

def underscore_key(k)
  if defined? Rails
    k.to_s.underscore.to_sym
  else
    to_snake_case(k.to_s).to_sym
  end
end

def to_snake_case(string)
  string.gsub(/::/, '/').
  gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
  gsub(/([a-z\d])([A-Z])/,'\1_\2').
  tr("-", "_").
  downcase
end

def convert_hash_keys(value)
  case value
    when Array
      value.map { |v| convert_hash_keys(v) }
      # or `value.map(&method(:convert_hash_keys))`
    when Hash
      Hash[value.map { |k, v| [underscore_key(k), convert_hash_keys(v)] }]
    else
      value
  end
end

here are some small tests to prove the functionality:

p convert_hash_keys({abc:"x"})          # => {:abc=>"x"}
p convert_hash_keys({abcDef:"x"})       # => {:abc_def=>"x"}
p convert_hash_keys({AbcDef:"x"})       # => {:abc_def=>"x"}
p convert_hash_keys(["abc"])            # => ["abc"]
p convert_hash_keys([abc:"x"])          # => [{:abc=>"x"}]
p convert_hash_keys([abcDef:"x"])       # => [{:abc_def=>"x"}]

I hope that meets your requirements.

Rabl helps with JSON going out, but I believe this is parsing JSON coming in. — Jesse Wolgamott, Feb 19 '13 at 13:44

Parse JSON in Rails app that is camelCase

1 Answers1