Question

This is an actual working example, which i have broken down and simplified on the request from two members in previous post containing more details. These codes I have extracted and rewritten to solve persistent problem: undefined method “profile” for nil:NilChass for nearly two days.

I use gem “faker”, and SQLite Database Browser omitting controller and views and focusing on modelling issue.

The original problem arose in Goal.rb with the error message stating: “undefined method `profile’ for nil:NilClass”. According to SQLite DB Browser, user and profile records have successfully created.

The problem lies a line “user.profile.lbm_lbs” under Goal.rb model. I do not quite understand why user.profile does not exist even though user.profile has been created via admin.profile = Profile.create!(name…) sample_data.rake (gem faker) appling bundle exec rake db:populate

The previous link I posted:
RAILS: How to make new collection.build in a callback?

BffmModel::Application.routes.draw do
  resources :users do
    resource :profile
    resource :goal
    resource :tdee
    resources :progress_charts
  end
end

# == Schema Information
#
# Table name: users
#
#  id              :integer         not null, primary key
#  email           :string(255)
#  password_digest :string(255)
#  created_at      :datetime        not null
#  updated_at      :datetime        not null
#  remember_token  :string(255)
#

class User < ActiveRecord::Base
    attr_accessible :email, :email_confirmation, :password, :password_confirmation

    has_secure_password
    has_one :profile
    has_one :goal
    has_one :tdee
    has_many :progress_charts

    before_save { |user| user.email = email.downcase }
    before_save :create_remember_token

    VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i

    validates :email, :confirmation => true, :presence => true, 
                        length: { maximum: 50 },
                        format: { with: VALID_EMAIL_REGEX },
                        uniqueness: { case_sensitive: false }

    validates :email_confirmation, :presence => true
    validates :password, length: { minimum: 6 }
    validates :password_confirmation, presence: true

    private

        def create_remember_token
            self.remember_token = SecureRandom.urlsafe_base64
        end
end

# == Schema Information
#
# Table name: profiles
#
#  id               :integer         not null, primary key
#  name             :string(255)
#  surname          :string(255)
#  gender           :string(255)
#  date_of_birth    :date
#  body_weight_lbs  :integer
#  height_in_feets  :integer
#  height_in_inches :integer
#  bf_pct           :decimal(5, 2)
#  bf_lbs           :decimal(5, 2)
#  lbm_lbs          :decimal(5, 2)
#  user_id          :integer
#  created_at       :datetime        not null
#  updated_at       :datetime        not null
#

class Profile < ActiveRecord::Base
    attr_accessible :name, :surname, :gender, :date_of_birth, :body_weight_lbs,
                    :bf_pct, :height_in_feets, :height_in_inches
    belongs_to :user

    before_save :set_gender
    before_save :calculate_body_fat_lbs
    before_save :calculate_lean_body_mass_lbs

    private

        def set_gender
            if self.gender == "1"
                self.gender = "Male"
            elsif self.gender == "2"
                self.gender = "Female"
            end
        end

        def calculate_body_fat_lbs
            self.bf_lbs = ( self.bf_pct / 100 ) * self.body_weight_lbs
            self.bf_lbs = self.bf_lbs.round(0)
        end

        def calculate_lean_body_mass_lbs
            self.lbm_lbs = self.body_weight_lbs - self.bf_lbs
        end
end

# == Schema Information
#
# Table name: goals
#
#  id                    :integer         not null, primary key
#  desired_bf_pct        :decimal(, )
#  goal_type             :string(255)
#  ideal_body_weight_lbs :decimal(5, 2)
#  ideal_bfm_lbs         :decimal(5, 2)
#  fat_to_lose_lbs       :decimal(5, 2)
#  lbm_to_gain_lbs       :decimal(5, 2)
#  user_id               :integer
#  created_at            :datetime        not null
#  updated_at            :datetime        not null
#

class Goal < ActiveRecord::Base
  attr_accessible :desired_bf_pct, :goal_type

  belongs_to :user

  before_save :set_goal
  before_save :calculate_ideal_body_weight_lbs

  private

    def set_goal
      if self.goal_type == "1"
        self.goal_type = "Lose Fat"
      elsif self.goal_type == "2"
        self.goal_type = "Gain Muscles"
      end
    end

    def calculate_ideal_body_weight_lbs

      self.ideal_body_weight_lbs = user.profile.lbm_lbs / ( 1 - ( self.desired_bf_pct / 100 ) )
      self.ideal_body_weight_lbs = self.ideal_body_weight_lbs.round(0)
    end
end

/lib/tasks/sample_data.rake as a testing data

namespace :db do
  desc "Fill database with sample data"
  task populate: :environment do
    admin = User.create!(email: "[e-mail]",
                         email_confirmation: "[e-mail]",
                         password: "foobar",
                         password_confirmation: "foobar")

    admin.profile = Profile.create!(name: "Michael",
                                    surname: "Colins",
                                    gender: "Male",
                                    date_of_birth: "1975-03-05",
                                    body_weight_lbs: 200,
                                    bf_pct: 25.5,
                                    height_in_feets: 5,
                                    height_in_inches: 11 )

    admin.goal = Goal.create!(  desired_bf_pct: 12,
                                goal_type: "Lose Fat")

    admin.tdee = Tdee.create!( tdee_calc_type: "Harris-Benedict",
                  activity_lvl: "BMR x 1.2")
  end
end

Thank you.

Answer 1

admin.goal = Goal.create!(  desired_bf_pct: 12,
                            goal_type: "Lose Fat")

This line here is tripping you up.

Goal.create!(  desired_bf_pct: 12,
               goal_type: "Lose Fat")

This part is going to create a new Goal. During this step, the :user relation is not set. that means the user method in Goal will return nil. Since nil has no method profile, you can’t call user.profile from within the calculate_ideal_body_weight_lbs method called before the Goal is saved. With the code as you have it, you must explicitly set the :user relation.

Goal.create!(  desired_bf_pct: 12,
               goal_type: "Lose Fat",
               user: admin )