ActiveModel::MissingAttributeError: 无法写入未知属性 `user_id` [英] ActiveModel::MissingAttributeError: can't write unknown attribute `user_id`
本文介绍了ActiveModel::MissingAttributeError: 无法写入未知属性 `user_id`的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试实施评论"作为我正在构建的项目的任务的一部分.
I am trying to implement a "comment" feature as part of my assignment for an project I am building.
在课程的早些时候，我们创建了一个评论表，并让 Faker gem 生成虚假评论.
Earlier in the course we created a comment table and had the Faker gem generate fake comments.
我的说明如下:
评论必须与用户相关联，因此在评论表中添加一个 user_id 外键.记得也要给它添加一个索引；
Comments must be associated with users, so add a user_id foreign key to the comments table. Remember to add an index to it too;
更新 User 模型以便您可以调用 user.comments，并更新 Comment 模型以便您可以调用 comment.user；
Update the User model so you can call user.comments, and the Comment model so you can call comment.user;
修改seeds.rb文件，在运行db:reset时创建有效的注释；
Modify the seeds.rb file to create valid comments when you run db:reset;
最初我试图运行我的 rails generate 命令，但一直遇到这个错误:
Initially I tried to run my rails generate commands but kept running into this error:
▶ rake db:migrate
== 20150508143445 CreateComments: migrating ===================================
-- create_table(:comments)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:
SQLite3::SQLException: table "comments" already exists: CREATE TABLE "comments" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "description" text, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL) /Users/jon/code/bloccit/db/migrate/20150508143445_create_comments.rb:3:in `change'
-e:1:in `<main>'
ActiveRecord::StatementInvalid: SQLite3::SQLException: table "comments" already exists: CREATE TABLE "comments" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "description" text, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL)
/Users/jon/code/bloccit/db/migrate/20150508143445_create_comments.rb:3:in `change'
-e:1:in `<main>'
SQLite3::SQLException: table "comments" already exists
/Users/jon/code/bloccit/db/migrate/20150508143445_create_comments.rb:3:in `change'
-e:1:in `<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)
所以我发现我需要从课程开始时删除旧表.我是在控制台中完成的.
So I discovered that I needed to delete the old table from the start of the course. I did this in the console.
ActiveRecord::Base.connection.execute("drop table comments")
它似乎起作用了.然后我就可以在终端中运行这些了.</p>
It seemed to work. I was then able to run these in terminal.
▶ rake db:migrate
== 20150508143445 CreateComments: migrating ===================================
-- create_table(:comments)
-> 0.0015s
== 20150508143445 CreateComments: migrated (0.0016s) ==========================
== 20150508152354 DropComments: migrating =====================================
== 20150508152354 DropComments: migrated (0.0000s) ============================
▶ rails g migration AddCommentToUsers commed_id:integer:index
invoke active_record
create db/migrate/20150508155200_add_comment_to_users.rb
▶ rake db:migrate
== 20150508155200 AddCommentToUsers: migrating ================================
-- add_column(:users, :commed_id, :integer)
-> 0.0010s
-- add_index(:users, :commed_id)
-> 0.0012s
== 20150508155200 AddCommentToUsers: migrated (0.0023s) =======================
models/comment.rb
class Comment < ActiveRecord::Base
belongs_to :user
end
models/user.rb
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable, :confirmable
has_many :posts
has_many :comments
# CarrierWave method for attribute functionality
mount_uploader :avatar, AvatarUploader
# These methods check the role of a user in the database
def admin?
role == 'admin'
end
def moderator?
role == 'moderator'
end
end
migrations/create_comments.rb
class CreateComments < ActiveRecord::Migration
def change
create_table :comments do |t|
t.text :description
t.timestamps null: false
end
end
end
迁移/add_comment_to_users.rb
class AddCommentToUsers < ActiveRecord::Migration
def change
add_column :users, :commed_id, :integer
add_index :users, :commed_id
end
end
在我的seeds.rb中我已经改变了
# Create Comments
50.times do
Comment.create!(
# user: users.sample, # we have not yet associated Users with Comments
post: posts.sample,
description: Faker::Lorem.paragraph
)
end
到
# Create Comments
50.times do
Comment.create!(
user: users.sample,
description: Faker::Lorem.paragraph
)
end
现在，当我运行 rake db:reset 时，我收到此错误.
Now when I run rake db:reset I get this error.
▶ rake db:reset
-- create_table("advertisements", {:force=>:cascade})
-> 0.0047s
-- create_table("answers", {:force=>:cascade})
-> 0.0010s
-- add_index("answers", ["question_id"], {:name=>"index_answers_on_question_id"})
-> 0.0014s
-- create_table("comments", {:force=>:cascade})
-> 0.0010s
-- create_table("posts", {:force=>:cascade})
-> 0.0010s
-- add_index("posts", ["topic_id"], {:name=>"index_posts_on_topic_id"})
-> 0.0010s
-- add_index("posts", ["user_id"], {:name=>"index_posts_on_user_id"})
-> 0.0014s
-- create_table("questions", {:force=>:cascade})
-> 0.0010s
-- create_table("summaries", {:force=>:cascade})
-> 0.0010s
-- add_index("summaries", ["post_id"], {:name=>"index_summaries_on_post_id"})
-> 0.0010s
-- create_table("topics", {:force=>:cascade})
-> 0.0036s
-- create_table("users", {:force=>:cascade})
-> 0.0015s
-- add_index("users", ["commed_id"], {:name=>"index_users_on_commed_id"})
-> 0.0009s
-- add_index("users", ["comment_id"], {:name=>"index_users_on_comment_id"})
-> 0.0012s
-- add_index("users", ["email"], {:name=>"index_users_on_email", :unique=>true})
-> 0.0015s
-- add_index("users", ["reset_password_token"], {:name=>"index_users_on_reset_password_token", :unique=>true})
-> 0.0017s
-- initialize_schema_migrations_table()
-> 0.0034s
rake aborted!
ActiveModel::MissingAttributeError: can't write unknown attribute `user_id`
/Users/jon/code/Bloccit/db/seeds.rb:45:in `block in <top (required)>'
/Users/jon/code/Bloccit/db/seeds.rb:44:in `times'
/Users/jon/code/Bloccit/db/seeds.rb:44:in `<top (required)>'
-e:1:in `<main>'
Tasks: TOP => db:setup => db:seed
(See full trace by running task with --trace)
这是完整的堆栈跟踪:
ActiveModel::MissingAttributeError: can't write unknown attribute `user_id`
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute.rb:138:in `with_value_from_database'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_set.rb:39:in `write_from_user'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_methods/write.rb:74:in `write_attribute_with_type_cast'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_methods/write.rb:56:in `write_attribute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_methods/dirty.rb:96:in `write_attribute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_methods.rb:373:in `[]='
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/associations/belongs_to_association.rb:83:in `replace_keys'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/associations/belongs_to_association.rb:14:in `replace'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/associations/singular_association.rb:17:in `writer'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/associations/builder/association.rb:123:in `user='
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_assignment.rb:54:in `public_send'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_assignment.rb:54:in `_assign_attribute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_assignment.rb:41:in `block in assign_attributes'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_assignment.rb:35:in `each'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/attribute_assignment.rb:35:in `assign_attributes'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/core.rb:559:in `init_attributes'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/core.rb:281:in `initialize'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/inheritance.rb:61:in `new'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/inheritance.rb:61:in `new'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/persistence.rb:50:in `create!'
/Users/jon/code/Bloccit/db/seeds.rb:45:in `block in <top (required)>'
/Users/jon/code/Bloccit/db/seeds.rb:44:in `times'
/Users/jon/code/Bloccit/db/seeds.rb:44:in `<top (required)>'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:268:in `load'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:268:in `block in load'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:240:in `load_dependency'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:268:in `load'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/engine.rb:547:in `load_seed'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/tasks/database_tasks.rb:250:in `load_seed'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/railties/databases.rake:180:in `block (2 levels) in <top (required)>'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:240:in `call'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:240:in `block in execute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:235:in `each'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:235:in `execute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:179:in `block in invoke_with_call_chain'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:172:in `invoke_with_call_chain'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:201:in `block in invoke_prerequisites'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:199:in `each'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:199:in `invoke_prerequisites'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:178:in `block in invoke_with_call_chain'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:172:in `invoke_with_call_chain'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:165:in `invoke'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activerecord-4.2.1/lib/active_record/railties/databases.rake:139:in `block (2 levels) in <top (required)>'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:240:in `call'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:240:in `block in execute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:235:in `each'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:235:in `execute'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:179:in `block in invoke_with_call_chain'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:172:in `invoke_with_call_chain'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/task.rb:165:in `invoke'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:150:in `invoke_task'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:106:in `block (2 levels) in top_level'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:106:in `each'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:106:in `block in top_level'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:115:in `run_with_threads'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:100:in `top_level'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:78:in `block in run'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:176:in `standard_exception_handling'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/rake/application.rb:75:in `run'
/Users/jon/code/Bloccit/bin/rake:8:in `<top (required)>'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:268:in `load'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:268:in `block in load'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:240:in `load_dependency'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:268:in `load'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/Users/jon/.rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
-e:1:in `<main>'
Tasks: TOP => db:setup => db:seed
我在这里被难住了.我认为通过删除旧表并运行新的生成命令 + 迁移一切就可以了.显然事实并非如此.
I am stumped here. I thought by deleting the old table and running the new generate commands + migrating everything would be in order. Apparently this is not the case.
我在这里做错了什么?
编辑以包含我的种子文件的第 45 行
Comment.create!(
推荐答案
您的迁移有误 - 不是将 user_id 添加到 comments，而是添加 users.commed.
You have the wrong migration - instead of adding a user_id to comments you add users.commed.
糟糕.这可能发生在我们最好的人身上.
Oops. It can happen to the best of us.
所以首先让我们创建一个迁移来清除这个错误:
So first let's create a migration to clean up this mistake:
class RemoveCommedFromUsers < ActiveRecord::Migration
def change
remove_column :users, :commed # will also remove the index
end
end
当然，如果应用程序尚未部署，您可以删除违规迁移并运行 rake db:reset
Of course if the App has not been deployed you could just delete the offending migration and run rake db:reset
让我们创建正确的迁移
rails g migration AddUserToComments user:belongs_to
生成以下迁移:
class AddUserToComments < ActiveRecord::Migration
def change
add_reference :comments, :user, index: true
end
end
add_reference 一次性创建索引和外键.
add_reference creates a index and a foreign key in one sweep.
这篇关于ActiveModel::MissingAttributeError: 无法写入未知属性 `user_id`的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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