Ruby on Rails教程：7.1.3使用mysql无法找到表'用户'

Question

这个问题涉及到在执行任何数据库操作之前，在rails中从sqlite切换到mysql，同时遵循Ruby on Rails教程（第二版）。 。

在我使用Ruby on Rails教程（第二版）做了任何数据库操作之前，我将config/database.yml中的数据库参数切换为使用mysql。一切都按7.1.3节进行。到目前为止，已经创建了users表，并成功将示例用户添加到表中。但是，当我去测试显示用户页面users/1时，我收到下面的错误消息。当使用mysql数据库而不是sqlite时，还有什么需要完成的吗？预先感谢您的支持！

错误：

ActiveRecord::StatementInvalid in UsersController#show 

Could not find table 'users' 

完全跟踪：

activerecord (3.2.11) lib/active_record/connection_adapters/sqlite_adapter.rb:472:in `table_structure' 
activerecord (3.2.11) lib/active_record/connection_adapters/sqlite_adapter.rb:346:in `columns' 
activerecord (3.2.11) lib/active_record/connection_adapters/schema_cache.rb:12:in `block in initialize' 
activerecord (3.2.11) lib/active_record/model_schema.rb:228:in `yield' 
activerecord (3.2.11) lib/active_record/model_schema.rb:228:in `default' 
activerecord (3.2.11) lib/active_record/model_schema.rb:228:in `columns' 
activerecord (3.2.11) lib/active_record/model_schema.rb:237:in `columns_hash' 
activerecord (3.2.11) lib/active_record/relation/delegation.rb:7:in `columns_hash' 
activerecord (3.2.11) lib/active_record/relation/finder_methods.rb:331:in `find_one' 
activerecord (3.2.11) lib/active_record/relation/finder_methods.rb:312:in `find_with_ids' 
activerecord (3.2.11) lib/active_record/relation/finder_methods.rb:107:in `find' 
activerecord (3.2.11) lib/active_record/querying.rb:5:in `find' 
app/controllers/users_controller.rb:4:in `show' 
actionpack (3.2.11) lib/action_controller/metal/implicit_render.rb:4:in `send_action' 
actionpack (3.2.11) lib/abstract_controller/base.rb:167:in `process_action' 
actionpack (3.2.11) lib/action_controller/metal/rendering.rb:10:in `process_action' 
actionpack (3.2.11) lib/abstract_controller/callbacks.rb:18:in `block in process_action' 
activesupport (3.2.11) lib/active_support/callbacks.rb:414:in `_run__1973165003296325481__process_action__197160741547540830__callbacks' 
activesupport (3.2.11) lib/active_support/callbacks.rb:405:in `__run_callback' 
activesupport (3.2.11) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks' 
activesupport (3.2.11) lib/active_support/callbacks.rb:81:in `run_callbacks' 
actionpack (3.2.11) lib/abstract_controller/callbacks.rb:17:in `process_action' 
actionpack (3.2.11) lib/action_controller/metal/rescue.rb:29:in `process_action' 
actionpack (3.2.11) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action' 
activesupport (3.2.11) lib/active_support/notifications.rb:123:in `block in instrument' 
activesupport (3.2.11) lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
activesupport (3.2.11) lib/active_support/notifications.rb:123:in `instrument' 
actionpack (3.2.11) lib/action_controller/metal/instrumentation.rb:29:in `process_action' 
actionpack (3.2.11) lib/action_controller/metal/params_wrapper.rb:207:in `process_action' 
activerecord (3.2.11) lib/active_record/railties/controller_runtime.rb:18:in `process_action' 
actionpack (3.2.11) lib/abstract_controller/base.rb:121:in `process' 
actionpack (3.2.11) lib/abstract_controller/rendering.rb:45:in `process' 
actionpack (3.2.11) lib/action_controller/metal.rb:203:in `dispatch' 
actionpack (3.2.11) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch' 
actionpack (3.2.11) lib/action_controller/metal.rb:246:in `block in action' 
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:73:in `call' 
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:73:in `dispatch' 
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:36:in `call' 
journey (1.0.4) lib/journey/router.rb:68:in `block in call' 
journey (1.0.4) lib/journey/router.rb:56:in `each' 
journey (1.0.4) lib/journey/router.rb:56:in `call' 
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:601:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call' 
rack (1.4.5) lib/rack/etag.rb:23:in `call' 
rack (1.4.5) lib/rack/conditionalget.rb:25:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/head.rb:14:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/params_parser.rb:21:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/flash.rb:242:in `call' 
rack (1.4.5) lib/rack/session/abstract/id.rb:210:in `context' 
rack (1.4.5) lib/rack/session/abstract/id.rb:205:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/cookies.rb:341:in `call' 
activerecord (3.2.11) lib/active_record/query_cache.rb:64:in `call' 
activerecord (3.2.11) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call' 
activesupport (3.2.11) lib/active_support/callbacks.rb:405:in `_run__2423197318852707609__call__2019361553739003282__callbacks' 
activesupport (3.2.11) lib/active_support/callbacks.rb:405:in `__run_callback' 
activesupport (3.2.11) lib/active_support/callbacks.rb:385:in `_run_call_callbacks' 
activesupport (3.2.11) lib/active_support/callbacks.rb:81:in `run_callbacks' 
actionpack (3.2.11) lib/action_dispatch/middleware/callbacks.rb:27:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/reloader.rb:65:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/remote_ip.rb:31:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call' 
railties (3.2.11) lib/rails/rack/logger.rb:32:in `call_app' 
railties (3.2.11) lib/rails/rack/logger.rb:16:in `block in call' 
activesupport (3.2.11) lib/active_support/tagged_logging.rb:22:in `tagged' 
railties (3.2.11) lib/rails/rack/logger.rb:16:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/request_id.rb:22:in `call' 
rack (1.4.5) lib/rack/methodoverride.rb:21:in `call' 
rack (1.4.5) lib/rack/runtime.rb:17:in `call' 
activesupport (3.2.11) lib/active_support/cache/strategy/local_cache.rb:72:in `call' 
rack (1.4.5) lib/rack/lock.rb:15:in `call' 
actionpack (3.2.11) lib/action_dispatch/middleware/static.rb:62:in `call' 
railties (3.2.11) lib/rails/engine.rb:479:in `call' 
railties (3.2.11) lib/rails/application.rb:223:in `call' 
rack (1.4.5) lib/rack/content_length.rb:14:in `call' 
rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service' 
/opt/bitnami/ruby/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service' 
/opt/bitnami/ruby/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run' 
/opt/bitnami/ruby/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread' 

Answer 1

从您提供的堆栈跟踪，它看起来像你的应用程序是不是在你的MySQL数据库指向。

activerecord (3.2.11) lib/active_record/connection_adapters/sqlite_adapter.rb:472:in table_structure'` < - 在sqlite_adapter，而不是一个MySQL适配器

点请确保您使用的mysql2宝石，不要忘记修改你的Gemfile后运行bundle install。另外，请确保在修改database.yml文件后重新启动服务器。