请同时参阅this post。
注意：当前rake任务会在设置帖子对象时保存用户和主题对象，但不保存帖子或标签。
问题：在我的rake任务（如下所示）中描述这种关系的正确方法是什么，以便它不会抛出无法批量分配属性异常？
以下是我的步骤：
第1步：创建模型
class Post < ActiveRecord::Base
belongs_to :topic, inverse_of: :posts
has_and_belongs_to_many :tags
attr_accessible :title, :description, :content, :tags_attributes
accepts_nested_attributes_for :tags, allow_destroy: true, reject_if: lambda {|attrs| attrs.all? {|key, value| value.blank?}}
end
class Tag < ActiveRecord::Base
has_and_belongs_to_many :posts
attr_accessible :tag_name #UPDATE
end
class Topic < ActiveRecord::Base
has_many :posts, inverse_of: :topic
attr_accessible :topic_name, :posts_attributes
accepts_nested_attributes_for :posts, allow_destroy: true, reject_if: lambda {|attrs| attrs.all? {|key, value| value.blank?}}
end
因此，我的Post模型是Topic的孩子，Post与Tags有HABTM关系。
第2步：创建佣金任务
namespace :db do
desc "Fill database with sample data"
task :posts => :environment do
Rake::Task['db:reset'].invoke
make_users
make_topics
make_posts
end
end
def make_users
puts "making users" + "..."
5.times do |n|
name = Faker::Name.name
password = "foo"
email = "example-#{n+1}@example.com"
user = User.create!(
codename: name,
email: email,
password: password,
password_confirmation: password)
end
end
def make_topics
puts "making topics"+"..."
3.times do
t = Faker::Lorem.words(1)
topic = Topic.create!(topic_name: t)
end
end
def make_posts
puts "making posts" + "..."
User.all(limit: 3).each do |user|
Topic.all.each do |topic|
10.times do
content = Faker::Lorem.paragraphs(3)
description = Faker::Lorem.words(10)
title = Faker::Lorem.words(4)
tag_1 = Faker::Lorem.words(1)
tag_2 = Faker::Lorem.words(1)
tag_3 = Faker::Lorem.words(1)
post = user.posts.create!(title: title,
posts_attributes: [{topic_name: @topic}],
description: description,
content: content,
tags_attributes: [{tag_name: tag_1}, {tag_name: tag_2}, {tag_name: tag_3}])
end
end
end
端
第3步：现在运行rake任务
...
making users...
making posts...
rake aborted!
Can't mass-assign protected attributes: posts_attributes
...
...
/lib/tasks/make_posts.rake:45:in `block (3 levels) in make_posts'
/lib/tasks/make_posts.rake:38:in `times'
/lib/tasks/make_posts.rake:38:in `block (2 levels) in make_posts'
/lib/tasks/make_posts.rake:36:in `each'
/lib/tasks/make_posts.rake:36:in `block in make_posts'
/lib/tasks/make_posts.rake:35:in `each'
/lib/tasks/make_posts.rake:35:in `make_posts'
/lib/tasks/make_posts.rake:7:in `block (2 levels) in <top (required)>'
...
...
既然我无法完成我的佣金任务，我就进入了控制台，这就是错误：
Topic Load (1.5ms) SELECT "topics".* FROM "topics" LIMIT 1
=> #<Topic id: 1, topic_name: "---\n- aut\n", created_at: "2012-02-14 21:06:41", updated_at: "2012-02-14 21:06:41">
irb(main):007:0> topic.posts_attributes = {"1"=>{tag_name:"hammer time"}}
ActiveModel::MassAssignmentSecurity::Error: Can't mass-assign protected attributes: tag_name
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activemodel-3.2.1/lib/active_model/mass_assignment_security/sanitizer.rb:48:in `process_removed_attributes'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activemodel-3.2.1/lib/active_model/mass_assignment_security/sanitizer.rb:20:in `debug_protected_attribute_removal'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activemodel-3.2.1/lib/active_model/mass_assignment_security/sanitizer.rb:12:in `sanitize'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activemodel-3.2.1/lib/active_model/mass_assignment_security.rb:228:in `sanitize_for_mass_assignment'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/attribute_assignment.rb:75:in `assign_attributes'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/base.rb:495:in `initialize'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/reflection.rb:183:in `new'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/reflection.rb:183:in `build_association'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/association.rb:233:in `build_record'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/collection_association.rb:112:in `build'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/nested_attributes.rb:405:in `block in assign_nested_attributes_for_collection_association'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/nested_attributes.rb:400:in `each'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/nested_attributes.rb:400:in `assign_nested_attributes_for_collection_association'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/nested_attributes.rb:288:in `posts_attributes='
from (irb):7
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/railties-3.2.1/lib/rails/commands/console.rb:47:in `start'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/railties-3.2.1/lib/rails/commands/console.rb:8:in `start'
from /home/rhodee/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/railties-3.2.1/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'irb(main):008:0>
答案 0 :(得分：0)
为什么要将posts_attributes传递给user.posts.create？在我看来，您希望创建一个包含许多帖子的主题，在这种情况下，您应该改为user.topics.create。