无法激活mysql2(〜> 0.3.6),已经在Rails 3.1中激活了mysql2-0.3.2

Question

我只是试图获得在3.1下运行的rails应用程序的最基本的基本shell,当我运行bundle exec rake db:migrate时,我得到了这个奇怪的错误

Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` (can't activate mysql2 (~> 0.3.6), already activated mysql2-0.3.2. Make sure all dependencies are added to Gemfile.)

我在这里和其他地方读到的所有帖子都说我应该使用较新的mysql2适配器用于rails 3.1,所以我有 -

gem 'mysql2', '0.3.2'

在我的gemfile中.有些帖子建议使用 -

gem 'mysql2', '~> 0.3'

但这给我带来了同样的错误.宝石安装在 -

/Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/mysql2-0.3.2

有人建议我再次在我的宝石文件中切换该行,这次是 -

gem 'mysql2', '< 0.3'

但是当我这样做时,运行bundle install,然后尝试再次运行迁移,我得到 -

An error has occurred, all later migrations canceled:
undefined method `rows' for nil:NilClass

我的完整迁移文件如下所示 -

class CreatePlaces < ActiveRecord::Migration
  def change
    create_table :places do |t|
      t.string :title
      t.string :meta_description
      t.string :permalink, :limit => 60
      t.string :name, :limit => 60
      t.string :address
      t.string :state, :limit => 2
      t.string :region, :limit => 3
      t.float :latitude
      t.float :longitude
      t.text :description
      t.boolean :active, :default => true

      t.timestamps
    end
    add_index :places, [:permalink, :state, :region, :latitude, :longitude, :active], :name => 'places_index'
  end
end

运行该迁移的全部输出是 -

==  CreatePlaces: migrating ===================================================
-- create_table(:places)
   -> 0.0925s
-- add_index(:places, [:permalink, :state, :region, :latitude, :longitude, :active], {:name=>"places_index"})
   -> 0.1097s
==  CreatePlaces: migrated (0.2023s) ==========================================

rake aborted!
An error has occurred, all later migrations canceled:

undefined method `rows' for nil:NilClass

没有以后的迁移,这是唯一的迁移,因为这是一个我刚开始尝试让Rails 3.1正常运行的应用程序.删除数据库并重新创建它会让我到同一个地方.

我可以从控制台访问地方 -

ruby-1.9.2-p180 :001 > Place
   (0.3ms)  SHOW TABLES
   (0.1ms)  SHOW TABLES
   (1.1ms)  describe `places`
 => Place(id: integer, title: string, meta_description: string, permalink: string, name: string, address: string, state: string, region: string, latitude: float, longitude: float, description: text, active: boolean, created_at: datetime, updated_at: datetime) 

但是,当我真的试图在地方做一个发现或任何事情时,我得到以下错误 -

Place.find(:all)
ArgumentError: wrong number of arguments (3 for 2)
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/mysql2-0.2.7/lib/active_record/connection_adapters/mysql2_adapter.rb:634:in `select'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/connection_adapters/abstract/database_statements.rb:9:in `select_all'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/connection_adapters/abstract/query_cache.rb:62:in `select_all'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/base.rb:470:in `find_by_sql'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/relation.rb:111:in `to_a'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/relation/finder_methods.rb:155:in `all'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/relation/finder_methods.rb:105:in `find'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/activerecord-3.1.0.rc5/lib/active_record/base.rb:437:in `find'
    from (irb):2
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/railties-3.1.0.rc5/lib/rails/commands/console.rb:45:in `start'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/railties-3.1.0.rc5/lib/rails/commands/console.rb:8:in `start'
    from /Users/mark/.rvm/gems/ruby-1.9.2-p180@rails310pre/gems/railties-3.1.0.rc5/lib/rails/commands.rb:40:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

有人有主意吗？我现在已经挖了18个小时,只是在圈子里跑.

谢谢, - 马克

Answer 1

Active Record对哪些版本mysql2兼容有自己的要求.这是Rails 3.1 的代码行.您必须使用mysql2满足这些要求的版本.

请安装mysql2适配器:( gem install activerecord-mysql2-adapter无法激活mysql2(〜> 0.3.6),已激活mysql2-0.3.2.确保所有依赖项都已添加到Gemfile中.)

这就是说Rails期望mysql2版本大于0.3.6且小于0.4.0,但发现版本为0.3.2.如果您更改Gemfile以请求此范围内的版本,那么Active Record应该很高兴.也许

gem 'mysql2', '0.3.6'

更改Gemfile后不要忘记更新您的软件包.

bundle update mysql2

Answer 2

这也让我拔掉了头发。我能得到的唯一合理的解决方案是切换到 mysql2 gem 的 master 分支。

gem 'mysql2', :git => 'git://github.com/brianmario/mysql2.git'

在此更新之后，我的 Rails 3.1.0.rc5 应用程序可以从 MySQL 启动。（在发表这篇文章时，gem 的最新版本是 0.3.6）