CODEWITHSUNDEEP
ruby-on-rails
RubyNoob
RubyNoob

Reputation: 547

Update in Ruby model method not feeding through controller

I hope someone can help. I suspect this is an embarrassingly newbie question, but then, I'm embarassingly new. I've tried everywhere I can think of for an answer to this and tried every permutation I can think of.

Task: I'm working through an example in a Ruby tutorial that manages a online shopping cart. The task is to create a button next to each item displayed in the cart, enabling you to decrement the amount of a single item by 1.

Problem: When I click on the "Decrement" button in my view next to an item with a quantity of one, it disappears from the cart, as expected. But when I click on the button next to an item with a quantity of more than one, nothing happens.

Code

View:

<td><%= button_to("Decrement", decrement_line_item_path(line_item), method: :post ) %>
</td>

(I have set a member route in routes.rb so that it accesses the decrement action on "POST")

Controller:

def decrement
    @cart = set_cart
    @line_item = @cart.line_items.find_by(params[:id])
    @line_item = @cart.decrement_line_item_quantity(@line_item.id)
    respond_to do |format|
        format.html {redirect_to store_url}
    end
end

(there's a set_cart method in a concerns file that just gets or sets the cart based on a session, and I know that works).

Model:

def decrement_line_item_quantity(item_id)
  item_to_decrement = line_items.find_by(id: item_id)
  if item_to_decrement.quantity > 1
    item_to_decrement.quantity -= 1
  else
    item_to_decrement.destroy
  end
  item_to_decrement
end

My debugger says that:

  1. item_to_decrement.quantity decreases in the model method, as expected
  2. @line_item.quantity is also decreased in the controller method, as expected

But the value for the line item's quantity in the actual cart appears to be unchanged in the controller method. I check @cart.line_items.find_by(params[:id]).quantity in my debugger after returning from the model method, and it hasn't changed.

This means that when I come to render my cart later, the quantity of an item with multiple units is not decreased, and so nothing happens.

Can someone tell me what I missed? This is the very first time I've used Stack Overflow, so I'm still learning. Have read the guidelines, and I hope I'm following them appropriately. Apologies for any transgressions and thanks so much in advance.

Upvotes: 2

Views: 64

Answers (1)

jvperrin
jvperrin

Reputation: 3368

You have to save the record after you decrement the quantity, otherwise the change in the quantity will not get persisted to the database:

def decrement_line_item_quantity(item_id)
  item_to_decrement = line_items.find_by(id: item_id)
  if item_to_decrement.quantity > 1
    item_to_decrement.quantity -= 1
    item_to_decrement.save
  else
    item_to_decrement.destroy
  end
  item_to_decrement
end

Upvotes: 1

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