Rails - Aug 2013 - How to present Rails form datetime select in different time zone?

Hello,

I have a Rails application with a default time zone of UTC. This works fine 
for almost everything. Now I have a situation where I would like to present 
the values in a datetime_select offset by a specific time zone. As far as I 
know, this helper does not have an option to specify the time zone that is 
used when persisting this data. When the form is submitted, it only sends 
the year, month, day, hour, and minute fields. ActiveRecord is responsible 
for converting these values into the time zone configured for the 
application. In this case, I want to change the time zone for only these 
fields so that it is localized to the user (but still store the correct UTC 
time). How can I make this change? Thanks for your help!

--Andrew

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On 22 August 2013 00:59, Andrew Havens
<andrewh-k20JcXJavzGBUy7/sJONFg@public.gmane.org>
wrote:
> Hello,
>
> I have a Rails application with a default time zone of UTC. This works fine
> for almost everything. Now I have a situation where I would like to present
> the values in a datetime_select offset by a specific time zone. As far as I
> know, this helper does not have an option to specify the time zone that is
> used when persisting this data. When the form is submitted, it only sends
> the year, month, day, hour, and minute fields. ActiveRecord is responsible
> for converting these values into the time zone configured for the
> application. In this case, I want to change the time zone for only these
> fields so that it is localized to the user (but still store the correct UTC
> time). How can I make this change? Thanks for your help!
You could adjust the values in the controller prior to saving the data.

Colin

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I found a way to do it. To convert the multi-parameter attributes that are 
submitted in the form to a specific time zone, add a method in your 
controller to manually convert the params into a datetime object. I chose 
to add this to the controller because I did not want to affect the model 
behavior. You should still be able to set a date on the model and assume 
your date was set correctly.

def create
  convert_datetimes_to_pdt("start_date")
  convert_datetimes_to_pdt("end_date")
  @model = MyModel.new(params[:my_model])
  # ...end
def update
  convert_datetimes_to_pdt("start_date")
  convert_datetimes_to_pdt("end_date")
  # ...end
def convert_datetimes_to_pdt(field)
  datetime = (1..5).collect {|num| params[''my_model''].delete
"#{field}(#{num}i)" }
  if datetime[0] and datetime[1] and datetime[2] # only if a date has been set
    params[''my_model''][field] = Time.find_zone!("Pacific
Time (US & Canada)").local(*datetime.map(&:to_i))
  endend

Now the datetime will be adjusted to the correct time zone. However, when 
the user goes to edit the time, the form fields will still display the time 
in UTC. To fix this, we can wrap the fields in a call toTime.use_zone:

Time.use_zone("Pacific Time (US & Canada)") do
  f.datetime_select :start_dateend

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