ActiveModel::UnknownAttributeError: unknown attribute when seeding belongs_to relationship

问题

Trying to seed a has_many/belongs_to relationship. A user has_many scripts, a script belongs_to a user.

When seeding the script, I get this error:

ActiveModel::UnknownAttributeError: unknown attribute 'user_id' for Script.

I'd think that this line in my migration would create a user_id attribute for script?

t.belongs_to :user, index: true, foreign_key: true

app/models/script.rb

class Script < ApplicationRecord
  belongs_to :user
  has_many :commits
  has_many :script_users, through: :commits, source: :user
end

app/models/user.rb

class User < ActiveRecord::Base
  has_many :scripts
  has_many :used_scripts, through: :commits, source: :script
  has_many :commits
end

db/migrate/20171231022826_create_scripts.rb

class CreateScripts < ActiveRecord::Migration[5.1]
  def change
    create_table :scripts do |t|
      t.string :name
      t.string :skill
      t.string :bot_for
      t.string :game_for

      t.belongs_to :user, index: true, foreign_key: true

      t.timestamps
    end
  end
end

db/seeds.rb

admin = User.create!(
  email: 'a@a.com',
  password: 'adminadmin',
  password_confirmation: 'adminadmin'
)

script = Script.create!(
  name: 'YWoodcutter',
  skill: 'Woodcutting',
  bot_for: 'Android',
  game_for: "CandyLand,
  user_id: admin.id
)

ActiveModel::UnknownAttributeError: unknown attribute 'user_id' for Script. I've made sure to rake:db reset and still get error.

Thank you

UPDATE:

I did a few things and it's working OK now. I believe the issue may have been that my user migration was created after my script migration. The user migration should done before scripts, so I changed the dates to change the order they were migrated in. Did a rake rake db:rollback & db:reset for good measure too.

回答1:

belongs_to is an alias of reference and it should work same as references

If its not working for you just try with following solution

class CreateScripts < ActiveRecord::Migration[5.1]
  def change
    create_table :scripts do |t|
      t.string :name
      t.string :skill
      t.string :bot_for
      t.string :game_for

      t.references :user, index: true, foreign_key: true

      t.timestamps
    end
  end
end

回答2:

Create Model with below line

rails g model script references:user

It will by default below line in migration file

t.references :user, foreign_key: true

and add belongs_to :user in script model . It might be t.references :user in rails 5 not t.belongs_to :user

来源：https://stackoverflow.com/questions/48334075/activemodelunknownattributeerror-unknown-attribute-when-seeding-belongs-to-re

标签

ruby-on-rails

activerecord

ruby-on-rails-5