mysql - 在现有项目上从 sqlite3 更改为 mysql

Question

我按照其他解决方案中的建议添加了 gem mysql2，然后尝试创建模型，但我遇到了同样的错误。

下面是我的database.yml 文件和错误消息。另外，请注意，我正在遵循一个教程，其中我需要首先生成模型，然后运行 ​​db:migrate。

default: &default
  adapter: mysql
  database: myrubyblog
  username: root
  password: root123
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000

development:
  adapter: mysql
  database: myrubyblog
  username: root
  password: root123
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000
  # Warning: The database defined as "test" will be erased and
  # re-generated from your development database when you run "rake".
  # Do not set this db to the same as development or production.
test:
  adapter: mysql
  database: myrubyblog
  username: root
  password: root123
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000

production:
  adapter: mysql
  database: myrubyblog
  username: root
  password: root123
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000

<小时/>

sania@sania-Swift-SF314-52:~/myrubyblog$ rails g model category name:string
/home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require': Could not load 'active_record/connection_adapters/mysql_adapter'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile. (LoadError)
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.1.6/lib/active_record/connection_adapters/connection_specification.rb:186:in `spec'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.1.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:880:in `establish_connection'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.1.6/lib/active_record/connection_handling.rb:58:in `establish_connection'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.1.6/lib/active_record/railtie.rb:124:in `block (2 levels) in <class:Railtie>'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:69:in `instance_eval'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:69:in `block in execute_hook'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:60:in `with_execution_control'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:65:in `execute_hook'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:50:in `block in run_load_hooks'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:49:in `each'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/lazy_load_hooks.rb:49:in `run_load_hooks'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.1.6/lib/active_record/base.rb:326:in `<module:ActiveRecord>'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activerecord-5.1.6/lib/active_record/base.rb:25:in `<top (required)>'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:356:in `active_record_configured?'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:273:in `disconnect_database'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:107:in `preload'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:153:in `serve'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:141:in `block in run'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:135:in `loop'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application.rb:135:in `run'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/spring-2.0.2/lib/spring/application/boot.rb:19:in `<top (required)>'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
    from /home/sania/.rbenv/versions/2.5.0/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
    from -e:1:in `<main>'

Answer 1

您必须在 config/database.yml 文件中包含一行来指定适配器是 mysql2 而不是 mysql。

适配器:mysql2而不是适配器:mysql

如果 mysql2 的安装和捆绑没问题，那么它就能工作。

您可能想要重新安装mysql2。您可以使用以下命令来完成此操作

gem “mysql2”

捆绑安装