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Module: ActiveRecord::QueryLogs

Overview

Automatically append comments to SQL queries with runtime information tags. This can be used to trace troublesome SQL statements back to the application code that generated these statements.

Query logs can be enabled via Rails configuration in config/application.rb or an initializer:

config.active_record.query_log_tags_enabled = true

By default the name of the application, the name and action of the controller, or the name of the job are logged. The default format is / SQLCommenter. The tags shown in a query comment can be configured via Rails configuration:

config.active_record.query_log_tags = [ :application, :controller, :action, :job ]

Active Record defines default tags available for use:

  • application

  • pid

  • socket

  • db_host

  • database

  • source_location

Action Controller adds default tags when loaded:

  • controller

  • action

  • namespaced_controller

Active Job adds default tags when loaded:

  • job

New comment tags can be defined by adding them in a ::Hash to the tags ::Array. Tags can have dynamic content by setting a Proc or lambda value in the ::Hash, and can reference any value stored by Rails in the context object. ::ActiveSupport::CurrentAttributes can be used to store application values. Tags with nil values are omitted from the query comment.

Escaping is performed on the string returned, however untrusted user input should not be used.

Example:

config.active_record.query_log_tags = [
  :namespaced_controller,
  :action,
  :job,
  {
    request_id: ->(context) { context[:controller]&.request&.request_id },
    job_id: ->(context) { context[:job]&.job_id },
    tenant_id: -> { Current.tenant&.id },
    static: "value",
  },
]

By default the name of the application, the name and action of the controller, or the name of the job are logged using the / SQLCommenter format. This can be changed via config.active_record.query_log_tags_format

Tag comments can be prepended to the query:

ActiveRecord::QueryLogs.prepend_comment = true

For applications where the content will not change during the lifetime of the request or job execution, the tags can be cached for reuse in every query:

config.active_record.cache_query_log_tags = true

Class Attribute Summary

Class Method Summary

Class Attribute Details

.cache_query_log_tags (rw)

This method is for internal use only.
[ GitHub ] 

  


# File 'activerecord/lib/active_record/query_logs.rb', line 115



attr_accessor :prepend_comment, :cache_query_log_tags # :nodoc:


  








  

    .prepend_comment   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 115



attr_accessor :prepend_comment, :cache_query_log_tags # :nodoc:


  








  

    .taggings   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 114



attr_reader :tags, :taggings, :tags_formatter # :nodoc:


  








  

    .taggings=(taggings)   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 117



def taggings=(taggings) # :nodoc:
  @taggings = taggings.freeze
  @handlers = rebuild_handlers
end


  








  

    .tags   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 114



attr_reader :tags, :taggings, :tags_formatter # :nodoc:


  








  

    .tags=(tags)   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 122



def tags=(tags) # :nodoc:
  @tags = tags.freeze
  @handlers = rebuild_handlers
end


  








  

    .tags_formatter   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 114



attr_reader :tags, :taggings, :tags_formatter # :nodoc:


  








  

    .tags_formatter=(format)   (rw)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 127



def tags_formatter=(format) # :nodoc:
  @formatter = case format
  when :legacy
    LegacyFormatter
  when :sqlcommenter
    SQLCommenter
  else
    raise ArgumentError, "Formatter is unsupported: #{format}"
  end
  @tags_formatter = format
end


  







Class Method Details



  

    .build_handler(name, handler = nil)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 180



def build_handler(name, handler = nil)
  handler ||= @taggings[name]
  if handler.nil?
    GetKeyHandler.new(name)
  elsif handler.respond_to?(:call)
    if handler.arity == 0
      ZeroArityHandler.new(handler)
    else
      handler
    end
  else
    IdentityHandler.new(handler)
  end
end


  








  

    .call(sql, connection)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 139



def call(sql, connection) # :nodoc:
  comment = self.comment(connection)

  if comment.blank?
    sql
  elsif prepend_comment
    "#{comment} #{sql}"
  else
    "#{sql} #{comment}"
  end
end


  








  

    .clear_cache  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 151



def clear_cache # :nodoc:
  self.cached_comment = nil
end


  








  

    .comment(connection)   (private)
  



  

    

Returns an SQL comment ::String containing the query log tags. Sets and returns a cached comment if .cache_query_log_tags is true.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 197



def comment(connection)
  if cache_query_log_tags
    self.cached_comment ||= uncached_comment(connection)
  else
    uncached_comment(connection)
  end
end


  








  

    .escape_sql_comment(content)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 213



def escape_sql_comment(content)
  # Sanitize a string to appear within a SQL comment
  # For compatibility, this also surrounding "/*+", "/*", and "*/"
  # characters, possibly with single surrounding space.
  # Then follows that by replacing any internal "*/" or "/ *" with
  # "* /" or "/ *"
  comment = content.to_s.dup
  comment.gsub!(%r{\A\s*/\*\+?\s?|\s?\*/\s*\Z}, "")
  comment.gsub!("*/", "* /")
  comment.gsub!("/*", "/ *")
  comment
end


  








  

    .query_source_location  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 155



def query_source_location # :nodoc:
  Thread.each_caller_location do |location|
    frame = LogSubscriber.backtrace_cleaner.clean_frame(location)
    return frame if frame
  end
  nil
end


  








  

    .rebuild_handlers   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 166



def rebuild_handlers
  handlers = []
  @tags.each do |i|
    if i.is_a?(Hash)
      i.each do |k, v|
        handlers << [k, build_handler(k, v)]
      end
    else
      handlers << [i, build_handler(i)]
    end
  end
  handlers.sort_by! { |(key, _)| key.to_s }
end


  








  

    .tag_content(connection)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 226



def tag_content(connection)
  context = ActiveSupport::ExecutionContext.to_h
  context[:connection] ||= connection

  pairs = @handlers.filter_map do |(key, handler)|
    val = handler.call(context)
    @formatter.format(key, val) unless val.nil?
  end
  @formatter.join(pairs)
end


  








  

    .uncached_comment(connection)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/query_logs.rb', line 205



def uncached_comment(connection)
  content = tag_content(connection)

  if content.present?
    "/*#{escape_sql_comment(content)}*/"
  end
end