Ruby: How do I include methods from a Module into a subclass of ActiveModel::Serializer -

i'm trying include method helper module activemodel::serializer subclass reason method not showing up.

here's simple helper module:

module helpers   module serialisers     def enforce_zulu_time(attribute)       define_method(attribute)         object.send(attribute).utc.iso8601 unless object.try(attribute).nil?       end     end   end end 

and here's test serialiser

class testserialiser < activemodel::serializer   include helpers::serialisers   attributes :updated_at    enforce_zulu_time :updated_at end 

and simple object serialise

class testitem   include activemodel::serializersupport   attr_reader :updated_at   def initialize     @updated_at = time.now.utc   end end 

and test

describe helpers::serialisers   let(:item)       { testitem.new }   let(:serialiser) { testserialiser.new(item) }   subject          { serialiser.attributes }    { expect(subject[:updated_at]).to be_zulu_time} end 

results in

`<class:testserialiser>': undefined method `enforce_zulu_time' testserialiser:class (nomethoderror) 

however if in testserialiser instead

class testserialiser < activemodel::serializer   attributes :updated_at    ['updated_at'].each |attribute|     define_method(attribute)       object.send(attribute).utc.iso8601 unless object.send(attribute).blank?     end   end end 

it works fine.

why enforce_zulu_time method not being included?

replace include helpers::serialisers extend helpers::serialisers since expect class methods.

another solution use activesupport::concern, see doc

---

sidenote

in order have code flexible free, recommend create own base class serializers, like:

class baseserializer < activemodel::serializer end 

then have serializers inherit it. way can add features easily.