ruby - How to work with an instance of a model without saving it to mongoid -

the users of rails app receiving lot of emails (lets represent signups new customers of users). when email received customer should created, , email should saved well. however, if customer exists (recognized email address of email), email email should not saved database. thought handled email.new, , save if email address recognized. seems email.new saves record database. how work email before deciding wether want save it?

example code:

class email   include mongoid::document    field :mail_address, type: string   belongs_to :user,     :inverse_of => :emails   belongs_to :customer, :inverse_of => :emails    def self.receive_email(user, mail)     puts user.emails.size                                                  # => 0     email = email.new(mail_address: mail.fetch(:mail_address), user: user) # here want create new instance of email without saving     puts user.emails.size                                                  # => 1     is_spam = email.test_if_spam     return is_spam if is_spam == true     is_duplicate = email.test_if_duplicate(user)   end    def test_if_spam     spam = true if self.mail_address == "spam@example.com"   end    def test_if_duplicate(user)     self.save     customer = customer.create_or_update_customer(user, self)     self.save if customer == "created"                                     # here want save email if passes customer "test"   end end  class customer   include mongoid::document    field :mail_address, type: string   belongs_to :user, :inverse_of => :customers   has_many :orders, :inverse_of => :customer    def self.create_or_update_customer(user, mail)     if user.customers.where(mail_address: mail.mail_address).size == 0       customer = mail.create_customer(mail_address: mail.mail_address, user: user)       return "created"     end   end end 

i'm going suggest fundamental reworking of function. try rewriting function this:

class email   def self.save_unless_customer_exists(user, mail)     email = email.new(       mail_address: mail.fetch(:mail_address),       user: user     )     return if email.customer or email.is_spam? or email.is_duplicate?     customer.create!(user: user)     email.save!   end end 

you won't able drop code in , expect work, because you'd have define is_spam? , is_duplicate?, can @ least see i'm coming from.

i'd recommend writing automated tests these functions if haven't already. pin down problem.