CODEWITHSUNDEEP
ruby-on-railsactiverecordruby-on-rails-4
kadhim
kadhim

Reputation: 45

Rails 4 - updating multiple table entries

I have around 25 items left for a product represented as product.stock = 25. Say I sell 5 of this specific product. Then I need to update the remaining stock entry for it to 25 - 5 = 20 or product.stock = product.stock - purchase.quantity.

How would I do this in my app. Would I place the above code somewhere in my controller?

I have a purchasing form that caters to the following:

I am not sure if I am being clear here or if the subject is relevant to my question.

Upvotes: 2

Views: 125

Answers (2)

infused
infused

Reputation: 24337

I would use ActiveRecord's decrement! method:

product.decrement!(:stock, purchase.quantity)

If the Purchase model is what tracks the final sale, then I would put this code in an ActiveRecord callback. For example:

class Purchase < ActiveRecord::Base
  belongs_to :product

  after_create :adjust_inventory

  def adjust_inventory
    product.decrement!(:stock, quantity)
  end
end

Purchase should also have a before_save validation that ensures enough stock exists to satisfy the order.

Upvotes: 2

Rafal
Rafal

Reputation: 2576

The method to decrement your stock should be implemented in the Product model

def decrement_stock(qty) self.stock = self.stock - qty self.save end

In your controller, you should call this method based on your params.

purchase_controller.rb

def update @product = Product.find(params[:id]) # Add validation to make sure you have any stock @product.decrement_stock(params[:quantity]) # Add other things you need to do and return the @product end

This is a fairly simplified version. You should actually have an Order model, an OrderLine model and a Product.

Upvotes: 0

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