Question

Is it possible to include the micro seconds when serializing a Rails object for ‘datetime’ fields? For example:

{ 
  "created_at":"2011-05-27T19:49:43.123456Z", 
  "updated_at":"2011-05-27T19:49:43.654321Z", 
  "..."
}

Answer 1

You need to override the default JSON formatting which is set in this file.
The format that you want to use would be this

strftime('%Y/%m/%d %H:%M:%S.%6N %z')

And you can patch JSON’s DateTime output like this

class DateTime
  def as_json(options = nil)
    strftime('%Y/%m/%d %H:%M:%S.%6N %z')
  end
end

And here is a reference of the fractional time references available in strftime()
%N – Fractional seconds digits, default is 9 digits (nanosecond)

%3N millisecond (3 digits)
%6N microsecond (6 digits)
%9N nanosecond (9 digits)