Iterate over records created_at dates and update with half of time from Time.now

I want to iterate over a fairly large collection of records in console, divide their date by half o开发者_如何学Pythonf the time since from Time.now and save it. So say records with created_at two months ago would now be 1 month old, 1 day becomes 12 hours etc.

This doesn't work but just for example:

Log.all.each{|l| l.created_at = l.created_at - (Time.now - l.created_at * 0.5); l.save}

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Try:

Log.all.each{|l| l.created_at = Time.at( l.created_at.to_f + (Time.now.to_f - l.created_at.to_f)/2 ); l.save}

Which should be the same as:

Log.all.each{|l| l.created_at = Time.at( (Time.now.to_f + l.created_at.to_f)/2 ); l.save}