Is there a way to avoid automatically updating Rails timestamp fields?

Question

If you have DB columns created_at and updated_at Rails will automatically set those values when you create and update a model object. Is there a way to save the model without touching those columns?

I am bringing in some legacy data and I would like to set those values from the corresponding values in the (differently named) legacy data fields. I'm finding when I set them on the model and then save the model, Rails appears to override the incoming values.

Of course I could just name the Rails model columns differently to prevent that, but after the data is imported, I want Rails to do its automatic timestamp thing.

Answer 1

Do this in a migration or in a rake task (or in the new database seeds if you're on edge rails):

ActiveRecord::Base.record_timestamps = false
begin
  run_the_code_that_imports_the_data
ensure
  ActiveRecord::Base.record_timestamps = true  # don't forget to enable it again!
end

You can safely set created_at and updated_at manually, Rails won't complain.

Note: This also works on individual models, e.g. User.record_timestamps = false

Answer 2

use update_column method instead:

http://api.rubyonrails.org/classes/ActiveRecord/Persistence.html#method-i-update_column

update_column(name, value)
# Updates a single attribute of an object, without calling save.

Validation is skipped.

Callbacks are skipped.

updated_at/updated_on column is not updated if that column is available.

Raises an ActiveRecordError when called on new objects, or when the name attribute is marked as readonly.

Answer 3

Rails 5 provides a convenient way to update a record without updating it's timestamp updated_at: https://api.rubyonrails.org/classes/ActiveRecord/Persistence.html#method-i-save

You, just need to pass touch:false while updating your record.

>> user = User.first
>> user.updated_at
=> Thu, 28 Apr 2016 20:01:57 IST +05:30
>> user.name = "Jose"
>> user.save(touch: false)
=> true

>> user.updated_at
=> Thu, 28 Apr 2016 20:01:57 IST +05:30