Question

我正在尝试为我的数据库播种，但我遇到了这个错误，并且作为初学者不知道如何解决它。我试图采集书签样本并将其分配给我的一些用户。任何想法为什么这会引发错误？这是错误：

vagrant@rails-dev-box:~/code/bookmarks$ rake db:seed
rake aborted!
NoMethodError: undefined method `sample' for #<Class:0xaa90cf4>
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activerecord-4.0.5/lib/active_record/dynamic_matchers.rb:22:in `method_missing'
/home/vagrant/code/bookmarks/db/seeds.rb:47:in `block (2 levels) in <top (required)>'
/home/vagrant/code/bookmarks/db/seeds.rb:46:in `times'
/home/vagrant/code/bookmarks/db/seeds.rb:46:in `block in <top (required)>'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activerecord-4.0.5/lib/active_record/relation/delegation.rb:13:in `each'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activerecord-4.0.5/lib/active_record/relation/delegation.rb:13:in `each'
/home/vagrant/code/bookmarks/db/seeds.rb:45:in `<top (required)>'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:223:in `load'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:223:in `block in load'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:214:in `load_dependency'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activesupport-4.0.5/lib/active_support/dependencies.rb:223:in `load'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/railties-4.0.5/lib/rails/engine.rb:540:in `load_seed'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activerecord-4.0.5/lib/active_record/tasks/database_tasks.rb:154:in `load_seed'
/home/vagrant/.rvm/gems/ruby-2.0.0-p481/gems/activerecord-4.0.5/lib/active_record/railties/databases.rake:181:in `block (2 levels) in <top (required)>'
Tasks: TOP => db:seed

编辑：这是我的seeds.rb文件：

require 'faker'

# Create a User
 # user = User.new(
 #   name:     'First Last',
 #   email:    'firstlast@gmail.com',
 #   password: 'password',
 # )
 # user.skip_confirmation!
 # user.save

#Create Users
5.times do
  user = User.new(
    name:     Faker::Name.name,
    email:    Faker::Internet.email,
    password: Faker::Lorem.characters(10)
  )
  user.skip_confirmation!
  user.save!
end
users = User.all


#Create Bookmarks
10.times do
  Bookmark.create!(
    url:    Faker::Internet.url
  )
end
bookmarks = Bookmark.all

#Create Topics
10.times do
  Topic.create!(
    name:   Faker::Lorem.sentence
  )
end
topics = Topic.all

users.each do |user|
  3.times do
    user.bookmarks << Bookmark.sample
  end
end

topics.each do |topic|
  3.times do
    user.topics << Topic.sample
 end
end

puts "Seed finished"
puts "#{User.count} users created"
puts "#{Bookmark.count} bookmarks created"
puts "#{Topic.count} topics created"

提前感谢您的帮助！

Answer 1

无论你在调用.sample，它之前的对象显然都不是正确的对象类型。它应该是一个数组或者是＆＃39;集合＆＃39;查询数据库时会出现这种情况。像这样......

posts = Post.all

posts.sample可以正常使用

任何不是数组（或类似数组）的对象都没有＆＃39;样本＆＃39;您可以使用的方法

Answer 2

您无法在课程上调用sample，因为这不是有效的方法。 sample方法用于数组或ActiveRecord :: Relation数组。

例如，每个都会返回一个随机的

[0,1,2,3].sample

(0..10).to_a.sample

Post.all.sample

但是，这些例子之类的内容会产生错误。

User.sample

NoMethodError: undefined method 'sample' for #<Class:0x00000007faa378>

(9..199).sample

NoMethodError: undefined method 'sample' for 9..199:Range

Rake db：seed NoMethodError：未定义的方法`sample＆＃39;

2 个答案: