find created_at in local time

rubyonrails-talk
1

Hello and thanks for taking the time to read this,

last night I came across two problems from which the first one - I am sure - is easy to solve. But as I am a beginner I am unable to find the solution.

As I learned through the night rails stores created_at dates in utc. Sure enough my local time zone is not utc :slight_smile: When I have an item and use the method created_at rails translates the time to my local time zone.

So when I add an item at 0:15 am local time and want to list all the items for today with

@items = Item.find(:all, :conditions => [ "created_at LIKE ?", "#{Time.now.to_date}%" ])

this item will never be found as its created_at date is yesterday. My first idea was to add 7200 two created_at in the find clause, but that would be an ugly workaround (I even did not get that to work...).

Can You tell me what would be the correct solution to translate?

And now the second question: Is there (already) a best practice to query this in rails 3? I didn't find a solution to do a "LIKE" query without a plugin, so how can one get all items created today out of the database?

@orders = Order.where(:created_at.to_date => Time.now.to_date) does not work as I cannot add the method to_date to a symbol.

Thank You all greetings Sven

2

Hello and thanks for taking the time to read this,

last night I came across two problems from which the first one - I am sure - is easy to solve. But as I am a beginner I am unable to find the solution.

As I learned through the night rails stores created_at dates in utc. Sure enough my local time zone is not utc :slight_smile: When I have an item and use the method created_at rails translates the time to my local time zone.

So when I add an item at 0:15 am local time and want to list all the items for today with

@items = Item.find(:all, :conditions => [ "created_at LIKE ?", "#{Time.now.to_date}%" ])

this item will never be found as its created_at date is yesterday. My first idea was to add 7200 two created_at in the find clause, but that would be an ugly workaround (I even did not get that to work...).

Can You tell me what would be the correct solution to translate?

You can get the current UTC time using:

Time.now.utc

And now the second question: Is there (already) a best practice to query this in rails 3? I didn't find a solution to do a "LIKE" query without a plugin, so how can one get all items created today out of the database?

@orders = Order.where(:created_at.to_date => Time.now.to_date) does not work as I cannot add the method to_date to a symbol.

Yeah, you're right, using LIKE for this isn't great. If you're looking for times that occur during today (local time) then what you're really looking for is times that occur between midnight today and midnight tomorrow. So I would probably do conditions like:

midnight = Time.now.midnight.utc # find last midnight in local time, then convert to UTC

@items = Item.find(:all,   :conditions => ["created_at >= ? AND created_at < ?",     midnight,     midnight.advance(:days => 1)   ] )

Chris

3

Hi Sven,

Can You tell me what would be the correct solution to translate?

In addition to Chris' recommendations, you should check out the Rails ActiveSupport::CoreExtensions helpers like .beginning_of_day and .end_of_day methods which, IMHO, are more readable than using :advance. (http://as.rubyonrails.org/classes/ActiveSupport/CoreExtensions/Date/Calculations.html)

I'd also recommend the TZInfo library (http://tzinfo.rubyforge.org/) if you're going to need to do reporting of this sort for clients in more than one timezone.

HTH, Bill

4

Thank You all for Your help!

That was exactly what I needed.

Greetings Sven

5

Bill Walton wrote:

In addition to Chris' recommendations, you should check out the Rails ActiveSupport::CoreExtensions helpers like .beginning_of_day and .end_of_day methods which, IMHO, are more readable than using :advance.

It's also possible to improve readability using more Ruby like idioms:

@items = Item.find(:all, :conditions => {:created_at => Date.today...Date.today + 1.day } )

SELECT * FROM "items" WHERE ("items"."created_at" >= '2010-09-02' AND 'items"."created_at" < '2010-09-03')

6

But going back to the OP's original point, that will give all items created on that day UTC whereas I think he wanted items created today local time.

Colin

7

Colin Law wrote: