неинициализированная константа при посеве

Question

Пытается посеять с помощью Ruby on Rails в ubuntu и postgresql (sudo rake db:seed), и он продолжает бросать ошибку uninitialized constant. Это то, что я получаю:

boris@alpha:~/Desktop/wikiful$ sudo rake db:seed --trace 
[sudo] password for boris: 
** Invoke db:seed (first_time) 
** Execute db:seed 
** Invoke db:abort_if_pending_migrations (first_time) 
** Invoke environment (first_time) 
** Execute environment 
** Execute db:abort_if_pending_migrations 
rake aborted! 
uninitialized constant Category::Articles 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord- 

4.0.2/lib/active_record/inheritance.rb:125:in `compute_type' 
    /usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/reflection.rb:178:in `klass' 
    /usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/associations/association.rb:123:in `klass' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/associations/collection_association.rb:37:in `reader' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/associations/builder/association.rb:70:in `articles' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validator.rb:151:in `block in validate' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validator.rb:150:in `each' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validator.rb:150:in `validate' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/validations/presence.rb:5:in `validate' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:283:in `_callback_before_7' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:397:in `_run__1018118611__validate__callbacks' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:80:in `run_callbacks' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validations.rb:373:in `run_validations!' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validations/callbacks.rb:106:in `block in run_validations!' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:373:in `_run__1018118611__validation__callbacks' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:80:in `run_callbacks' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validations/callbacks.rb:106:in `run_validations!' 
/usr/local/lib/ruby/gems/2.0.0/gems/activemodel-4.0.2/lib/active_model/validations.rb:314:in `valid?' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/validations.rb:70:in `valid?' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/validations.rb:77:in `perform_validations' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/validations.rb:51:in `save' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/attribute_methods/dirty.rb:32:in `save' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:270:in `block (2 levels) in save' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:326:in `block in with_transaction_returning_status' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/connection_adapters/abstract/database_statements.rb:202:in `block in transaction' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/connection_adapters/abstract/database_statements.rb:210:in `within_new_transaction' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/connection_adapters/abstract/database_statements.rb:202:in `transaction' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:209:in `transaction' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:323:in `with_transaction_returning_status' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:270:in `block in save' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:281:in `rollback_active_record_state!' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/transactions.rb:269:in `save' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/persistence.rb:37:in `create' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/persistence.rb:34:in `block in create' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/persistence.rb:34:in `collect' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/persistence.rb:34:in `create' 
/home/boris/Desktop/wikiful/db/seeds.rb:5:in `<top (required)>' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:223:in `load' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:223:in `block in load' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:214:in `load_dependency' 
/usr/local/lib/ruby/gems/2.0.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:223:in `load' 
/usr/local/lib/ruby/gems/2.0.0/gems/railties-4.0.2/lib/rails/engine.rb:540:in `load_seed' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/tasks/database_tasks.rb:154:in `load_seed' 
/usr/local/lib/ruby/gems/2.0.0/gems/activerecord-4.0.2/lib/active_record/railties/databases.rake:181:in `block (2 levels) in <top (required)>' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:236:in `call' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:236:in `block in execute' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:231:in `each' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:231:in `execute' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:175:in `block in invoke_with_call_chain' 
/usr/local/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:168:in `invoke_with_call_chain' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/task.rb:161:in `invoke' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:149:in `invoke_task' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:106:in `block (2 levels) in top_level' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:106:in `each' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:106:in `block in top_level' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:115:in `run_with_threads' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:100:in `top_level' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:78:in `block in run' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:165:in `standard_exception_handling' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/lib/rake/application.rb:75:in `run' 
/usr/local/lib/ruby/gems/2.0.0/gems/rake-10.1.1/bin/rake:33:in `<top (required)>' 
/usr/local/bin/rake:23:in `load' 
/usr/local/bin/rake:23:in `<main>' 
Tasks: TOP => db:seed 

Это мой семена файл:

# This file should contain all the record creation needed to seed the database with its default values. 
# The data can then be loaded with the rake db:seed (or created alongside the db with db:setup). 

# Create 8 seed categories 
categories = Category.create([ 
       { name: 'History'}, {name: 'Biology'}, {name: 'Literature'}, 
       { name: 'Mathematics'}, { name: 'Music Theory'}, { name: 'Computer Science'}, 
       { name: 'Sociology'}, {name: 'Chemistry'} 
     ]) 

# create 50 articles, with random titles, 250 words of content, and 
# randomly assign one of the categories above to each article 
for i in 0..49 
     title = Faker::Lorem.sentence(rand(2..10)).chomp('.') 
     content = Faker::Lorem.paragraph(word_count=250) 

     # randomly assign one of the categories we just created 
     category = Category.first(offset: rand(Category.count)) 
     a = Article.create(title: title, content: content, categories: [category,]) 
end 

Категория Модель:

class Category < ActiveRecord::Base 

    validates :name, presence: true 
    validates :name, uniqueness: true 

    has_many :article_categories 
    has_many :articles, through: :article_categories 
end 

---

articlecategory модель:

class ArticleCategory < ActiveRecord::Base 
    belongs_to :articles 
    belongs_to :categories 
end 

---

статья модель:

class Article < ActiveRecord::Base 
    belongs_to :user 

    validates :title, presence: true 
    validates :content, presence: true 

    has_many :article_categories 
    has_many :categories, through: :article_categories 

end 

совет спасибо

Answer 1

Я любопытно, что ваши модели выглядеть. Вы делаете небольшую ошибку, предполагая, что вы можете прикрепить категорию к атрибуту categories в своей модели Article. Вы должны иметь модель ArticleCategory, которая имеет has many through association с категориями и изделиями. Поэтому вместо присвоения категории атрибуту categories вы должны сделать что-то вроде этого.

ArticleCategory.create(article_id: a.id, category_id: category.id) 

в вашей следующей до последней строки.

Answer 2

Ваша модель присоединиться неправильно:

class ArticleCategory < ActiveRecord::Base 
    belongs_to :article # not articles 
    belongs_to :category # not categories 
end