这是我第一次尝试在 Rails 上使用 MySql。使用 sqlite3 也会发生这种情况，除了它指向我做“gem install activerecord-sqlite3-adapter”，它告诉我没有这样的 gem 命名它。
我正在使用最新的 Ruby 2.0。我正在使用最新的 Rails 3.2.13 我有 mysql2 (0.3.11) gem 我也有 activerecord-mysql2-adapter (0.0.3)
然而......它给了我以下信息：
C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/lib/bundler/rubygems_integration.rb:214:in 'block in replace_gem': Please install the mysql2 adapter: 'gem install activerecord-mysql2-adapter' (mysql2 is not part of the bundle. Add it to Gemfile.) (LoadError)
当我执行时捆绑器运行rails new [project name]
如果是 mysql2 gem 的错误，这个命令在 64 位 Windows 系统上成功安装了 mysql2：gem install mysql2 -v '0.3.11' -- '--with-mysql-lib="C:\MySQL\lib" --with-mysql-include="C:\MySQL\include"'
生成的 Gemfile 使用gem 'mysql2'正常，正如我被告知的那样。
Database.yml 如下：
development:
adapter: mysql2
encoding: utf8
reconnect: false
database: shop_development
pool: 5
username: charlie
password: *******
host: localhost
我已经手动创建了一个名为 [projectname]_development 的数据库。
C:\Users\Charlie\Documents\RailsProject\demo_app>rails s
=> Booting WEBrick
=> Rails 3.2.13 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/lib/bundler/rubygems_integ
ration.rb:214:in `block in replace_gem': Please install the mysql2 adapter: `gem
install activerecord-mysql2-adapter` (mysql2 is not part of the bundle. Add it
to Gemfile.) (LoadError)
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/connection_adapters/mysql2_adapter.rb:3:in `<top (required)>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/dependencies.rb:251:in `require'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/dependencies.rb:251:in `block in require'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/dependencies.rb:236:in `load_dependency'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/dependencies.rb:251:in `require'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/connection_adapters/abstract/connection_specification.rb:50:in `resol
ve_hash_connection'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/connection_adapters/abstract/connection_specification.rb:41:in `resol
ve_string_connection'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/connection_adapters/abstract/connection_specification.rb:25:in `spec'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/connection_adapters/abstract/connection_specification.rb:130:in `esta
blish_connection'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/railtie.rb:82:in `block (2 levels) in <class:Railtie>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/lazy_load_hooks.rb:36:in `instance_eval'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/lazy_load_hooks.rb:36:in `execute_hook'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/lazy_load_hooks.rb:43:in `block in run_load_hooks'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/lazy_load_hooks.rb:42:in `each'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activesupport-3.2.13/lib/ac
tive_support/lazy_load_hooks.rb:42:in `run_load_hooks'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/base.rb:720:in `<top (required)>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/activerecord-3.2.13/lib/act
ive_record/railtie.rb:88:in `block in <class:Railtie>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/i
nitializable.rb:30:in `instance_exec'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/i
nitializable.rb:30:in `run'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/i
nitializable.rb:55:in `block in run_initializers'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/i
nitializable.rb:54:in `each'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/i
nitializable.rb:54:in `run_initializers'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/a
pplication.rb:136:in `initialize!'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/r
ailtie/configurable.rb:30:in `method_missing'
from C:/Users/Charlie/Documents/RailsProject/demo_app/config/environment
.rb:5:in `<top (required)>'
from C:/Users/Charlie/Documents/RailsProject/demo_app/config.ru:3:in `re
quire'
from C:/Users/Charlie/Documents/RailsProject/demo_app/config.ru:3:in `bl
ock in <main>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/builder
.rb:51:in `instance_eval'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/builder
.rb:51:in `initialize'
from C:/Users/Charlie/Documents/RailsProject/demo_app/config.ru:in `new'
from C:/Users/Charlie/Documents/RailsProject/demo_app/config.ru:in `<mai
n>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/builder
.rb:40:in `eval'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/builder
.rb:40:in `parse_file'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/server.
rb:200:in `app'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/c
ommands/server.rb:46:in `app'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/server.
rb:304:in `wrapped_app'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rack-1.4.5/lib/rack/server.
rb:254:in `start'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/c
ommands/server.rb:70:in `start'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/c
ommands.rb:55:in `block in <top (required)>'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/c
ommands.rb:50:in `tap'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-3.2.13/lib/rails/c
ommands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'