Question

I’m using rails app as iOS backend. There is small problem – how to render timestamps with user’s timezone in json? I’m using default UTC timezone. How to converted it for example to +2? Maybe there is way how to override as_json method to convert timestamps before rendering?

Thanks for help!

Answer 1

You can convert the time to user’s timezone before rendering json, then the timezone will be included.

1.9.3p125 :006 > t = Time.now.utc
 => 2012-10-20 13:49:12 UTC 
1.9.3p125 :007 > {time: t}.to_json
 => "{\"time\":\"2012-10-20T13:49:12Z\"}" 
1.9.3p125 :008 > t = Time.now.in_time_zone("Beijing")
 => Sat, 20 Oct 2012 21:49:19 CST +08:00 
1.9.3p125 :009 > {time: t}.to_json
 => "{\"time\":\"2012-10-20T21:49:19+08:00\"}" 

UPDATE: To convert the time into user’s timezone for serialization, you can override this method read_attribute_for_serialization. See lib/active_model/serialization.rb of ActiveModel:

# Hook method defining how an attribute value should be retrieved for
# serialization. By default this is assumed to be an instance named after
# the attribute. Override this method in subclasses should you need to
# retrieve the value for a given attribute differently:
#
#   class MyClass
#     include ActiveModel::Validations
#
#     def initialize(data = {})
#       @data = data
#     end
#
#     def read_attribute_for_serialization(key)
#       @data[key]
#     end
#   end
#
alias :read_attribute_for_serialization :send