Ruby-on-rails 如何显示在 Rails 控制台中运行的 SQL 查询？
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How to show SQL queries run in the Rails console?
提问by randombits
When I run queries (e.g. MyModel.where(...)or record.associated_things) in the console, how can I see the actual database queries being run so I can gain more understanding of what is happening?
当我在控制台中运行查询（例如MyModel.where(...)或record.associated_things）时，我如何才能看到正在运行的实际数据库查询，以便更好地了解正在发生的事情？
回答by John Topley
Rails 3+
导轨 3+
Enter this line in the console:
在控制台中输入这一行：
ActiveRecord::Base.logger = Logger.new(STDOUT)
Rails 2
导轨 2
Enter this line in the console:
在控制台中输入这一行：
ActiveRecord::Base.connection.instance_variable_set :@logger, Logger.new(STDOUT)
回答by Abhi
回答by lakesare
There is an .explainmethod in Rails 4.
(.to_sqlworks too, but won't show includes)
.explainRails 4 中有一个方法。
（.to_sql也可以使用，但不会显示包含）
Category.includes(:products).explain
=> EXPLAIN for: SELECT "categories".* FROM "categories" 0|0|0|SCAN TABLE categories
EXPLAIN for: SELECT "categories_products".* FROM "categories_products" WHERE "categories_products"."category_id" IN (1, 2) 0|0|0|SCAN TABLE categories_products
EXPLAIN for: SELECT "products".* FROM "products" WHERE "products"."id" IN (1, 2, 3, 4, 5, 6, 7) 0|0|0|SEARCH TABLE products USING INTEGER PRIMARY KEY (rowid=?) 0|0|0|EXECUTE LIST SUBQUERY 1
回答by Aleksandar Pavi?
As from recently, you can use this:
从最近开始，你可以使用这个：
https://github.com/dejan/rails_panel
https://github.com/dejan/rails_panel
It consists of developer console panel add-on for chrome, and gem file which needs to be added to your application's Gemfilelike this:
它由 chrome 的开发者控制台面板插件和需要添加到应用程序的Gemfile 中的gem 文件组成，如下所示：
group :development do
gem 'meta_request'
end
Then run again:
然后再次运行：
bundle install
Restart your application, open it, and launch developer console, and you should see it like this:
重新启动您的应用程序，打开它，然后启动开发者控制台，您应该会看到如下所示：
回答by kaleb4eg
Starting from Rails 6 there is more convenient approach: simply add ActiveRecord::Base.verbose_query_logs = truein console and you will see all SQL calls and places where it was called. More info https://guides.rubyonrails.org/debugging_rails_applications.html#verbose-query-logs
从 Rails 6 开始，有更方便的方法：只需ActiveRecord::Base.verbose_query_logs = true在控制台中添加，您将看到所有 SQL 调用以及调用它的位置。更多信息https://guides.rubyonrails.org/debugging_rails_applications.html#verbose-query-logs
回答by Huy Vo
I prefer to set up logger level in config/application.rb:
我更喜欢在以下位置设置记录器级别config/application.rb：
config.after_initialize do
Rails.logger.level = (ENV['LOG_LEVEL'] || Logger::INFO).to_i
end
On production my ENV['LOG_LEVEL']will be set to the value of Logger::INFOand on my local machine it'll be Logger::DEBUG.
在生产中，我ENV['LOG_LEVEL']将被设置为 的值，Logger::INFO在我的本地机器上它将是Logger::DEBUG.
