class Jbuilder

{ "_first_name": "David" }

json.first_name "David"
json.key_format! ->(key){ "_" + key }

Lambdas can also be used.

{ "firstName": "David" }

json.first_name "David"
json.key_format! camelize: :lower

You can pass parameters to the method using a hash pair.

{ "AUTHOR": { "NAME": "David", "AGE": 32 } }

end
json.age 32
json.name "David"
json.author do
json.key_format! :upcase

Example:

the key. You can also pass in lambdas for more complex transformations.
will cause that function to be called on the key. So :upcase will upper case
Specifies formatting to be applied to the key. Passing in a name of a function

def key_format!(*args)
  @key_formatter = KeyFormatter.new(*args)
end