How to disable ActiveRecord logging for a certain column?

Question

I'm running into a problem which, in my opinion, must be a problem for most rails users but I could not find any solution for it yet.

When, for instance, performing a file upload of a potentially large, binary file and storing it in the database, you most certainly don't want rails or ActiveRecord to log this specific field in development mode (log file, stdout). In case of a fairly big file, this causes the query execution to break and almost kills my terminal.

Is there any reliable and non-hacky method of disabling logging for particular fields? Remember, I'm not talking about disabling logging for request parameters - this has been solved quite nicely.

Thanks for any information on that!

Answer 1

If this helps anyone, here is a Rails 4.1 compatible version of the snippet above that also includes redaction of non-binary bind params (e.g. a text or json column), and increases the logging to 100 char before redaction. Thanks for everyone's help here!

class ActiveRecord::ConnectionAdapters::AbstractAdapter
  protected

  def log_with_binary_truncate(sql, name="SQL", binds=[], statement_name = nil, &block)
    binds = binds.map do |col, data|
      if data.is_a?(String) && data.size > 100
        data = "#{data[0,10]} [REDACTED #{data.size - 20} bytes] #{data[-10,10]}"
      end
      [col, data]
    end

    sql = sql.gsub(/(?<='\\x[0-9a-f]{100})[0-9a-f]{100,}?(?=[0-9a-f]{100}')/) do |match|
      "[REDACTED #{match.size} chars]"
    end

    log_without_binary_truncate(sql, name, binds, statement_name, &block)
  end

  alias_method_chain :log, :binary_truncate
end

Answer 2

Create a file in config/initializers whitch modifies ActiveRecord::ConnectionAdapters::AbstractAdapter like so:

class ActiveRecord::ConnectionAdapters::AbstractAdapter
   protected

   def log_with_trunkate(sql, name="SQL", binds=[], &block)
     b = binds.map {|k,v|
       v = v.truncate(20) if v.is_a? String and v.size > 20
       [k,v]
     }
     log_without_trunkate(sql, name, b, &block)
   end

   alias_method_chain :log, :trunkate
end

This will trunkate all fields that are longer than 20 chars in the output log.