Display SQL Queries in Log with Rails 4

Display SQL queries in log with Rails 4

the rails console never writes to the log file, but you can achieve it quite easily, for example, if you execute following after starting the rails console

ActiveRecord::Base.logger = Logger.new STDOUT

rails will log all SQL statements to stdout, thus display them in your terminal. and since Logger.new accepts any stream as first argument, you could just let it write to the rails development.log:

ActiveRecord::Base.logger = Logger.new File.open('log/development.log', 'a')

How to show SQL queries run in the Rails console?

Rails 3+

Enter this line in the console:

ActiveRecord::Base.logger = Logger.new(STDOUT)

Rails 2

Enter this line in the console:

ActiveRecord::Base.connection.instance_variable_set :@logger, Logger.new(STDOUT)

Rails 4: Show SQL in console in production

ActiveRecord::Base.logger = Logger.new(STDOUT)

Execute it in rails console on your server, and then all the ActiveRecord generated SQL queries will be shown.

Rails: Show SQL Queries in Production Log

In your environments/production.rb

config.log_level = :debug

Remember you need to restart the web server to apply the changes.

Rails Logs: Only show Create, Update, and Destroy SQL statements in Logs and nothing else

You can disable logging of ActiveRecord database queries by setting the log_level to :info.

Then use Rails' ActiveSupport::Instrumentation and subscribe to the sql.active_record event.

Just add the following code into an initializer:

# in `config/initializers/query_logger.rb`
class QueryLogger
  def call(name, started, finished, unique_id, payload)
    query = payload[:sql]

    Rails.logger.info("SQL Query: #{query}") unless query.start_with?('SELECT')
  end
end

ActiveSupport::Notifications.subscribe('sql.active_record', QueryLogger.new)

How to show SQL query log generated by a RSpec test?

Put the following code in your specs:

Rails 7.0+

ActiveRecord.verbose_query_logs = true

Rails 5.2

ActiveRecord::Base.verbose_query_logs = true

Rails 3.0

ActiveRecord::Base.logger = Logger.new(STDOUT) if defined?(ActiveRecord::Base)

Thanks to everyone who commented for the Rails updates.

How do I turn on SQL debug logging for ActiveRecord in RSpec tests?

By default, all your db queries will be logged already in test mode. They'll be in log/test.log.

How to log Rails queries before they happen?

There is no standard way you can configure logger to output SQL query before execution.

But you can still log queries this way by extending ActiveRecord::LogSubscriber class.

# initializers/extensions/active_record_logger.rb
module Extensions
  module ActiveRecordLogger
    IGNORE_PAYLOAD_NAMES = ActiveRecord::LogSubscriber::IGNORE_PAYLOAD_NAMES

    # ActiveRecord::LogSubscriber doesn't implement this method.
    # This method will be invoked before event starts processing.
    # It's exactly we are looking for!
    def start(name, id, payload)
      super

      return unless logger.debug?
      return if IGNORE_PAYLOAD_NAMES.include?(payload[:name])

      name = payload[:name]
      sql = payload[:sql]

      name = color(name, nil, true)
      sql  = color(sql, nil, true)

      debug "STARTING #{name}  #{sql}"
    end
  end
end

ActiveRecord::LogSubscriber.include Extensions::ActiveRecordLogger

Now you will get query log before execution. For instance, querying

User.find 1

will produce

STARTING  User Load  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1
User Load (0.2ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 1]]
#<User id: 1, username: "dimakura", created_at: "2015-09-08 13:16:42", updated_at: "2015-09-08 13:16:42">

Rails - See generated SQL queries in Log files

Yes you can. If you go in the config/environments/production.rb file, there's a section like this:

# See everything in the log (default is :info)
# config.log_level = :debug

Uncomment the config.log_level line, and you'll get the same log in production as you would in dev.

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