self.save和有什么不一样！ 和self.update_attributes

Question

I have an after_create filter that leads to the following definition

def create_slug
  candidate = [self.make, self.model, self.year]
  self.slug = candidate.join('=').parameterize
  self.save!
end

I found out the SQL statement would take 6.4ms compare to usual 0.1 - 0.5ms

I tried changed it to self.update_attributes

def create_slug
  candidate = [self.make, self.model, self.year]
  self.update_attributes(slug: candidate.join('=').parameterize)
end

the SQL statement is 4.7ms.

I wonder if there is any difference in using the two methods.

Answer 1

save! is meant to raise on failure, not update_attributes which would return false . Thats the only difference I see, let aside the method signature

If you look at the internal its more obvious:

# File activerecord/lib/active_record/persistence.rb, line 246
def update(attributes)
  # The following transaction covers any possible database side-effects of the
  # attributes assignment. For example, setting the IDs of a child collection.
  with_transaction_returning_status do
    assign_attributes(attributes)
    save
  end
end