Manually set updated_at in Rails - ruby-on-rails

Question

I'm migrating my old blog posts into my new Rails blog, and I want their updated_at attribute to match the corresponding value on my old blog (not the date they were migrated into my new Rails blog).
How can I do this? When I set updated_at manually it gets overridden by the before_save callback.
Note: This question is only valid for Rails < 3.2.11. Newer versions of Rails allow you to manually set timestamps without them being overwritten.

Answer 1

If it's a one time thing you can turn record_timestamps on or off.
ActiveRecord::Base.record_timestamps = false
#set timestamps manually
ActiveRecord::Base.record_timestamps = true
When I ran into this issue with my app, I searched around for a bit and this seemed like it made the most sense to me. It's an initializer that I can call where I need to:
module ActiveRecord
class Base
def update_record_without_timestamping
class << self
def record_timestamps; false; end
end
save!
class << self
def record_timestamps; super ; end
end
end
end
end

Answer 2

As of recent versions of Rails (3.2.11 as per iGELs comment) you can set the updated_at property in code and the change will be honoured when saving.
I assume rails is keeping track of 'dirty' properties that have been manually changed and not overwriting on save.
> note = Note.last
Note Load (1.4ms) SELECT "notes".* FROM "notes" ORDER BY "notes"."id" DESC LIMIT 1
=> #<Note id: 39, content: "A wee note", created_at: "2015-06-09 11:06:01", updated_at: "2015-06-09 11:06:01">
> note.updated_at = 2.years.ago
=> Sun, 07 Jul 2013 21:20:47 UTC +00:00
> note.save
(0.4ms) BEGIN
(0.8ms) UPDATE "notes" SET "updated_at" = '2013-07-07 21:20:47.972990' WHERE "notes"."id" = 39
(0.8ms) COMMIT
=> true
> note
=> #<Note id: 39, content: "A wee note", created_at: "2015-06-09 11:06:01", updated_at: "2013-07-07 21:20:47">
So short answer, workarounds are not needed any longer in recent versions of rails.

Answer 3

I see two ways to accomplish this easily:
touch (Rails >=5)
In Rails 5 you can use the touch method and give a named parameter time like described in the documentation of touch
foo.touch(time: old_timestamp)
update_column (Rails >=4)
If you want it in Rails 4 and lower or want to avoid all callbacks you could use one of the update_column or update_columns methods which bypass all safe or touch callbacks and validations
foo.update_column(updated_at, old_timestamp)
or
foo.update_columns(updated_at: old_timestamp)

Answer 4

I took Andy's answer and modified it to accept blocks:
module ActiveRecord
class Base
def without_timestamping
class << self
def record_timestamps; false; end
end
yield
class << self
remove_method :record_timestamps
end
end
end
end

Answer 5

This is riffing off of Andy Gaskell's answer:
class ActiveRecord::Base
class_inheritable_writer :record_timestamps
def do_without_changing_timestamps
self.class.record_timestamps = false
yield
ensure
self.class.record_timestamps = true
end
end

Answer 6

The solution is to temporarily set ActiveRecord::Base.record_timestamps to false:
ActiveRecord::Base.record_timestamps = false
# Make whatever changes you want to the timestamps here
ActiveRecord::Base.record_timestamps = true
If you want a somewhat more robust solution, you may want to try something like what mrm suggested:
module ActiveRecord
class Base
def self.without_timestamping
timestamping = self.record_timestamps
begin
self.record_timestamps = false
yield
ensure
self.record_timestamps = timestamping
end
end
end
end
Then you can easily make changes to models without their timestamps being automatically updated:
ActiveRecord::Base.without_timestamping do
foo = Foo.first
bar = Bar.first
foo.updated_at = 1.month.ago
bar.updated_at = foo.updated_at + 1.week
foo.save!
bar.save!
end
Or, if you only want to update records from a specific class without timestamping:
module ActiveRecord
class Base
# Don't delete Rail's ActiveRecord::Base#inherited method
self.singleton_class.send(:alias_method, :__inherited__, :inherited)
def self.inherited(subclass)
__inherited__
# Adding class methods to `subclass`
class << subclass
def without_timestamping
# Temporarily override record_timestamps for this class
class << self
def record_timestamps; false; end
end
yield
ensure
class << self
remove_method :record_timestamps
end
end
end
end
end
end
E.g:
Foo.without_timestamping do
foo = Foo.first
bar = Bar.new(foo: foo)
foo.updated_at = 1.month.ago
foo.save! # Timestamps not automatically updated
bar.save! # Timestamps updated normally
end
Or you could use an approach similar to what Venkat D. suggested, which works on a per-instance basis:
module ActiveRecord
class Base
def without_timestamping
class << self
def record_timestamps; false; end
end
yield
ensure
class << self
remove_method :record_timestamps
end
end
end
end
E.g:
foo = Foo.first
foo.without_timestamping do
foo2 = Foo.new(parent: foo)
foo.updated_at = 1.month.ago
foo.save! # Timestamps not automatically updated
foo2.save! # Timestamps updated normally
end