ruby-on-rails – Rails与不同的数据库一起迁移

发布时间：2020-12-17 02:21:47 所属栏目：百科来源：网络整理

导读：我需要在另一个数据库中使用Devise和现有的用户表,所以我配置了我的 database.yml： development: adapter: postgresql encoding: unicode database: almoxarifado pool: 5 timeout: 5000 username: user password: pass host: localhostusers_development:

我需要在另一个数据库中使用Devise和现有的用户表,所以我配置了我的 database.yml：

development:
  adapter: postgresql
  encoding: unicode
  database: almoxarifado
  pool: 5
  timeout: 5000
  username: user
  password: pass
  host: localhost

users_development:
  adapter: postgresql
  encoding: unicode
  database: portal 
  pool: 5
  timeout: 5000
  username: user
  password: pass
  host: localhost
  schema_search_path: users

在我的模型中,我写了这段代码：

class User < ActiveRecord::Base
  establish_connection "users_#{Rails.env}"
  devise :database_authenticatable,:registerable,:recoverable,:rememberable,:trackable,:validatable
end

当我运行Rails c并调用模型类时,这个工作非常好.

迁移文件：

class AddDeviseToUsers < ActiveRecord::Migration
  def self.up
    ActiveRecord::Base.establish_connection "users_#{Rails.env}"
    change_table(:users) do |t|
      ## Database authenticatable
      t.string :email,:null => false,:default => ""
      t.string :encrypted_password,:default => ""

      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at

      ## Rememberable
      t.datetime :remember_created_at

      ## Trackable
      t.integer  :sign_in_count,:default => 0,:null => false
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip

      ## Confirmable
      # t.string   :confirmation_token
      # t.datetime :confirmed_at
      # t.datetime :confirmation_sent_at
      # t.string   :unconfirmed_email # Only if using reconfirmable

      ## Lockable
      # t.integer  :failed_attempts,:null => false # Only if lock strategy is :failed_attempts
      # t.string   :unlock_token # Only if unlock strategy is :email or :both
      # t.datetime :locked_at


      # Uncomment below if timestamps were not included in your original model.
      # t.timestamps
    end

    add_index :users,:email,:unique => true
    add_index :users,:reset_password_token,:unique => true
    # add_index :users,:confirmation_token,:unlock_token,:unique => true
    ActiveRecord::Base.establish_connection "#{Rails.env}"
  end

  def self.down
    # By default,we don't want to make any assumption about how to roll back a migration when your
    # model already existed. Please edit below which fields you would like to remove in this migration.
    raise ActiveRecord::IrreversibleMigration
  end
end

但rake db：migrate返回此错误：

==  AddDeviseToUsers: migrating =======================================
-- change_table(:users)
rake aborted!
An error has occurred,this and all later migrations canceled:

undefined method `rollback' for #<ActiveRecord::ConnectionAdapters::ClosedTransaction:0xbb06767c>
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

解决方法

由于我花了很多时间在这个和其他帖子中尝试所有替代方案,但没有成功,这里的解决方案对我有用

database.yml的

external_database:
  adapter: postgresql
  database: <%= ENV['DATABASE_NAME'] %>
  username: <%= ENV['DATABASE_USERNAME'] %>
  password: <%= ENV['DATABASE_PASSWORD'] %>
  host: <%= ENV['DATABASE_HOST'] %>
  port: <%= ENV['DATABASE_PORT'] || 5432 %>

车型/ yourmodel.rb

class YourModel < ActiveRecord::Base
  establish_connection :external_database
end

你的迁移

class YourMigration < ActiveRecord::Migration
  def self.up
    YourModel.connection.enable_extension "plpgsql"
    YourModel.connection.create_table :your_table_name,id: :uuid do |t|
      t.text :title
      ...
    end
  end

  def self.down
    YourModel.connection.drop_table :your_table_name
  end
end

说明：由于ActiveRecord :: Base.establish_connection关闭连接,我直接使用模型中的连接.此外,由于我使用UUID和uuid_generate_v4()方法作为默认值,我使用相同的连接启用了扩展

（编辑：李大同）

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