Rails Paperclip: update vs. update_attributes

Question

I realized something quite strange when attempting to upload an image via the paperclip gem for my user model (under the avatar attribute). For some reason there User.update and @user.update_attributes behaves differently. Does anyone know why this is so?

#using @user.update_attributes(user_avatar_params)
def update_profile_pic
    @user = User.find(params[:id])
    @user.update_attributes(user_avatar_params)
    puts @user.avatar_file_name.nil? # prints false as expected
    respond_to do |format|
      format.html { redirect_to :back }
      format.js
    end
end

#using User.update(@user.id, user_avatar_params)
def update_profile_pic
    @user = User.find(params[:id])
    User.update(@user.id, user_avatar_params)
    puts @user.avatar_file_name.nil? # prints true although successfully saves
    respond_to do |format|
      format.html { redirect_to :back }
      format.js
    end
end

And here is my strong params in the user_controller.rb

def user_avatar_params
  params.require(:user).permit(:avatar)
end

As affinities mentioned User.update returns the object based on the record it updated. So it is basically not the same object in the memory that user var point to. Try: user = User.update(user.id, user_avatar_params) and I believe you will get the same results in both cases. BTW, I think expected value in 'user.avatar_file_name.nil?' should be false, not true — Roaring Stones, Dec 29 '14 at 06:28
Thanks for the catch @RoaringStones. I have corrected the post. Yes when I use ```@user = User.update(user.id, user_avatar_params)``` it prints false as I expected. — Derrick Mar, Dec 29 '14 at 06:52

score 55 · Answer 1 · edited Sep 06 '17 at 09:20

55

For what it's worth, as of Rails 4.0.2, #update returns false if the update failed, not simply the object which the update failed for. Of further note, #update_attributes is simply an alias of #update now.

edited Sep 06 '17 at 09:20

Mahesh

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answered Aug 05 '16 at 14:52

jamesconant

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_"For what it's worth"_ This is worth a lot. I'm glad I scrolled down passed the accepted answer. – Joshua Pinter Sep 02 '20 at 19:07
Glad it helped :) – jamesconant Sep 03 '20 at 20:39

score 23 · Accepted Answer · edited Aug 29 '18 at 11:57

ActiveRecord.update has a behavior that may be throwing you off:

Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not. http://apidock.com/rails/ActiveRecord/Base/update/class

However the update_attributes will just return false.

Both of these use Model-level validations and so both should save or not save equally. However, the return values will be different.

As @RoaringStones pointed out, the solution is to use

user = User.update(user.id, user_avatar_params)

Yes I tried testing these in the exact same scenario. – Derrick Mar Dec 29 '14 at 06:47 — Derrick Mar, Dec 29 '14 at 06:47

score 19 · Answer 3 · answered Feb 19 '18 at 05:02

By the way, #update_attributes gonna be deprecated from Rails 6 (though this is not released yet)

please have a look at

for more details.

Rails Paperclip: update vs. update_attributes

3 Answers3

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