Changing a value on a record in Ruby on Rails Controller

Question

I have the following code in my controller and I am wondering how I might add the current_user.id to the ingredient. I am new to ruby and am still learning the syntax, so any help would be greatly appreciated.

def create
  @ingredient = Ingredient.new(ingredient_params)
  @ingredient.user_id = @decoded_auth_token.id

  if @ingredient.save
    render json: @ingredient, status: :created, location: @ingredient
  else
    render json: @ingredient.errors, status: :unprocessable_entity
  end
end 

private

# Only allow a trusted parameter "white list" through.
def ingredient_params
  params.require(:ingredient).permit(:title, :quantity, :unit)
end

jvillian · Accepted Answer · 2019-04-11 21:23:21Z

2

I would suggest:

def create
  @ingredient = current_user.ingredients.new(ingredient_params)

  if @ingredient.save
    render json: @ingredient, status: :created, location: @ingredient
  else
    render json: @ingredient.errors, status: :unprocessable_entity
  end
end

That, naturally, assumes that User has_many :ingredients and Ingredient belongs_to :user.

BTW, I don't know why you have a $ in front of $current_user.id. What is that all about?

Based on your comment, I suspect you're going about things the wrong way. Presumably, you have:

class IngredientsController < ApplicationController
  ...
end

So, in ApplicationController, you could either (1) save your token to an instance variable, in which case it would be available in IngredientsController or (2) save it to the session, in which case it would also be available to IngredientsController.

I think it's not great to have current_user represent a token. That could lead to confusion for the future you. If I were you, I'd name the token variable something like, oh, I don't know, say, autenticated_token or even just token. Then, I would use current_user to hold an actual User instance (that you look up, presumable, using the token) so that you can do your current_user.ingredients.new(ingredients_params) business.

Also, I don't know what your design parameters are. But, I would speculate that you want to have User and Ingredient have a many-to-many relationship. Otherwise, you're going to end up with a lot of Ingredient records with the same name (like, 'egg') - assuming, naturally, that a lot of users have egg ingredients. Just a thought.

Based on your edit, I see you've changed:

@ingredient.user_id = $current_user

to:

@ingredient.user_id = @decoded_auth_token.id

I would guess that @decoded_auth_token.id != current_user.id. If you're @decoded_auth_token has a user_id, I would guess that you would want to use that, instead. Something like:

@ingredient.user_id = @decoded_auth_token.user_id

I suppose if Token belongs_to :user (or whatever your token class name is), then you could do:

@ingredient = @decoded_auth_token.user.ingredients.new(ingredient_params)

But, then I think you're getting sideways with the Law of Demeter. And you never want to get sideways with the Law.

I still prefer:

@ingredient = current_user.ingredients.new(ingredient_params)

But I suppose that's a matter of personal preference.

edited Apr 11, 2019 at 21:23

answered Apr 11, 2019 at 20:57

jvillian

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9 Comments

Nick Gallimore Over a year ago

I am handling authentication in the application controller and it decodes the json web token in there. I needed a way to retrieve the user_id from that token in another controller e.g., the ingredients controller.

Nick Gallimore Over a year ago

current_user is actually a token and not the users record from the database, so this does not work.

Nick Gallimore Over a year ago

Thanks! I re-worked it and realized I had the token available in the ingredients controller already. So I revised the question above. Imo I think I am best with how it is now. I want to keep track of each user's ingredient inventory. If I have two eggs it is okay, as long as they belong to different users. But as far as setting the user_id on the newly created ingredient do you have any ideas given this new information?

jvillian Over a year ago

I hear what you're saying about each user having their own egg. But, what happens when you want to find all users that have an egg ingredient?

Nick Gallimore Over a year ago

Thank you. I added it to the session and that fixed the problem. Way better than having a global variable. What you are saying about the database might be useful, and would definitely reduce the database size. I'm looking up many to many now.

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