Ruby on Rails rake db:seed undefined in rails tutorial

Question

I'm following this tutorial https://www.railstutorial.org/book/following_users#top and am at step 12.14. I've followed each step except the ones adding test data because I'm using this tutorial to help me learn to develop a follower following feature on my own project.

Here is the error message from my console:

rake aborted!
NoMethodError: undefined method `each' for nil:NilClass
/Users/alexanderkehaya/Desktop/wewrite/db/seeds.rb:13:in

Any ideas what I'm doing wrong/missing? Edit: How do I get the seed data to rake successfully?

Thanks for the help.

Here is my data:

ActiveRecord::Schema.define(version: 20141030023857) do

create_table "collaborators_stories", id: false, force: true do |t|
t.datetime "created_at"
t.datetime "updated_at"
t.integer  "collaborator_id"
t.integer  "story_id"
end

create_table "lines", force: true do |t|
t.string   "text"
t.integer  "score",            default: 0
t.integer  "depth",            default: 0
t.integer  "previous_line_id"
t.datetime "created_at"
t.datetime "updated_at"
t.integer  "user_id"
t.integer  "story_id"
end

create_table "relationships", force: true do |t|
t.integer  "follower_id"
t.integer  "followed_id"
t.datetime "created_at",  null: false
t.datetime "updated_at",  null: false
end

add_index "relationships", ["followed_id"], name: "index_relationships_on_followed_id"
add_index "relationships", ["follower_id", "followed_id"], name:      "index_relationships_on_follower_id_and_followed_id", unique: true
add_index "relationships", ["follower_id"], name: "index_relationships_on_follower_id"

create_table "stories", force: true do |t|
t.datetime "created_at"
t.datetime "updated_at"
end

create_table "users", force: true do |t|
t.string   "email",                  default: "", null: false
t.string   "encrypted_password",     default: "", null: false
t.string   "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer  "sign_in_count",          default: 0,  null: false
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.string   "current_sign_in_ip"
t.string   "last_sign_in_ip"
t.datetime "created_at"
t.datetime "updated_at"
t.string   "provider"
t.string   "uid"
t.string   "name"
t.string   "profile_image_url"
end

add_index "users", ["email"], name: "index_users_on_email", unique: true
add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique:   true

end

Here is my user.rb file:

class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :omniauthable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable

has_many :lines
has_many :active_relationships, class_name:  "Relationship",
                              foreign_key: "follower_id",
                              dependent:   :destroy
has_many :passive_relationships, class_name:  "Relationship",
                              foreign_key: "followed_id",
                              dependent:   :destroy
has_many :following, through: :active_relationships, source: :followed
has_many :followers, through: :passive_relationships, source: :follower
has_and_belongs_to_many :stories, :foreign_key => :collaborator_id, :join_table => :collaborators_stories

def profile_image_uri(size = "mini")
    # parse_encoded_uri(insecure_uri(profile_image_uri_https(size))) unless @attrs[:profile_image_url_https].nil?
    unless self.provider == "facebook"
        self.profile_image_url.sub! "normal", size  unless self.profile_image_url.nil?
    else
        self.profile_image_url
    end
end

#Follows a user.
def follow(other_user)
    active_relationships.create(followed_id: other_user.id)
end

 # Unfollows a user.
def unfollow(other_user)
    active_relationships.find_by(followed_id: other_user.id).destroy
end

 # Returns true if the current user is following the other user.
def following?(other_user)
    following.include?(other_user)
end
def self.find_for_twitter_oauth(auth, signed_in_resource=nil)


    user = User.where(:provider => auth.provider, :uid => auth.uid).first

    if user

      if user.profile_image_url != auth.extra.raw_info.profile_image_url 
         user.update_attribute(:profile_image_url, auth.extra.raw_info.profile_image_url)
      end

      return user 

    else
      registered_user = User.where(:email => auth.uid + "@twitter.com").first

      if registered_user

        return registered_user
      else

        user = User.create(name:auth.extra.raw_info.name,
                            provider:auth.provider, 
                            profile_image_url:auth.extra.raw_info.profile_image_url,
                            uid:auth.uid,
                            email:auth.uid+"@twitter.com",
                            password:Devise.friendly_token[0,20],
                          )
      end
    end 
  end

  def self.find_for_facebook_oauth(auth, signed_in_resource=nil)

    user = User.where(:provider => auth.provider, :uid => auth.uid).first
    if user

        if user.profile_image_url != auth.info.image 
         user.update_attribute(:profile_image_url, auth.info.image)
      end

      return user
    else
      registered_user = User.where(:email => auth.info.email).first
      if registered_user
        return registered_user
      else
        user = User.create(name:auth.extra.raw_info.name,
                            provider:auth.provider, 
                            profile_image_url:auth.info.image,
                            uid:auth.uid,
                            email:auth.info.email,
                            password:Devise.friendly_token[0,20],
                          )
  end   
 end
end
end

Here is my relationships.rb file:

class Relationship < ActiveRecord::Base
 belongs_to :follower, class_name: "User"
 belongs_to :followed, class_name: "User"
 validates :follower_id, presence: true
 validates :followed_id, presence: true
end

EDIT: I added my seeds file:

users = User.all
user  = users.first
following = users[2..50]
followers = users[3..40]
following.each { |followed| user.follow(followed) }
followers.each { |follower| follower.follow(user) }

Answer 1

The error message explains itself. undefined method 'each' for nil:NilClass tells you that you are tryiing to send each method to a nil object. It can be deduced that following and/or followers, on which you are calling each, are nil, not an ActiveRecord Relation object you hope it to be.

Did you remember to create User objects in your seed file? If your seed file is just as shown in your question, it wouldn't work because User model does not have any objects in it.

You must create them first as shown in here listing 12.14. You can either use FactoryGirl like Railstutorial does, or just plain Ruby.