initialization - Rails - initialize object instance variable -

i have 2 arrays initialise [] in prediction model's object.

if try:

def initialize     @first_estimation = []     @last_estimation = [] end

then many of unit tests fail.

 failure/error: assign(:prediction, prediction.new(      argumenterror:        wrong number of arguments (1 0)

however, if try:

def after_initialize     @first_estimation = []     @last_estimation = [] end

then arrays not instantiated.

how can instantiate arrays when object constructed without altering else?

since see parenthesis here prediction.new( deduce try pass params.

but initialize doesnt accept => boom

but wait, activerecord model?

if so, have use:

 after_initialize :set_arrays   def set_arrays    @first_estimation = []    @last_estimation = []  end

and maybe use attr_accessor too, dont know expect

Lix