Timezone-affected rails 3 app

Question

UPDATE:

Copied from comment made below:

I thought about using a web service against IP address for each visitor to the site but then I wondered about users looking at meetings in locations that span timezones so the timezone has to be associated with the location of the meeting being viewed, not where the user themselves are at that moment in time. I need a user to be able to see a list of meetings (with times and locations) and the times shown are the actual meeting times but the WHERE clause of the SELECT to list the meetings needs to take into account the timezone of each meeting location.

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I've looked around and there are plenty of questions asked about using timezones with a rails app.

The issue lies in the fact that the app needs to know which timezone a user is in for it to properly be able to run queries against the database to check for datetimes in the future, for instance.

I don't want regular visitors to my site to need to login for it to work correctly for them so I'm thinking along the following lines:

• Admin users login to post an item for a particular location and datetime
• When saving the item it uses the [lat,lng] of the location to call the Timezone gem to capture the timezone for the location
• I think I need this timezone to be added to an extra field on the same model as the [lat,lng] and the datetime (which rails saves as UTC) ( https://stackoverflow.com/a/2533323 )
• I need my model to combine the UTC datetime with its respective timezone so that when a regular user comes to the site the webpage selects items where the UTC+timezone datetimes are in the future

Does that sound possible/correct?

If it sounds confusing just say in a comment and I'll try to reword it a bit better if I can.

Can someone offer any code for the model to create a virtual attribute (I think) that combines UTC datetime with a timezone field?

Thanks

Answer 1

Won't it be better to have the list of countries and their timezones? When user comes to site determine from what country he is and than trying to use native rails timezone methods. For example I have User and Table models that have created_at params:

Time.zone => (GMT+00:00) UTC
User.last.created_at => Mon, 25 Jun 2012 21:17:25 UTC +00:00
Table.last.created_at => Mon, 16 Jul 2012 14:08:17 UTC +00:00

Time.zone = 'Moscow' => "Moscow"
Time.zone => (GMT+04:00) Moscow

User.last.created_at => Tue, 26 Jun 2012 01:17:25 MSK +04:00
Table.last.created_at => Mon, 16 Jul 2012 18:08:17 MSK +04:00

How to determine the country you should look for gems or some services. I think it will be the service that determine the user country by his IP address.