class Jbuilder

def extract!(object, *attributes)

json.(@person, :name, :age)

You can also use the call syntax instead of an explicit extract! call:

{ "name": David", "age": 32 }, { "name": Jamie", "age": 31 }

json.extract! @person, :name, :age

@person = { name: 'David', age: 32 }

or you can utilize a Hash

@person = Struct.new(:name, :age).new('David', 32)

Example:

Extracts the mentioned attributes or hash elements from the passed object and turns them into attributes of the JSON. 
def extract!(object, *attributes)
  if ::Hash === object
    _extract_hash_values(object, attributes)
  else
    _extract_method_values(object, attributes)
  end
end