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I have the following show-view, where i display basic information about Product and display other User's Products.

<h1>Book <%= @product.name %></h1> <% @products.each do |product| %> <ul> <%= product.name %> <%= link_to "Make offer", {controller: "offers", :action => 'create', id: product.id } %> </ul>

Controller

def show @product = current_user.products.find(params[:id]) @products = Product.all end

My goal is to make Offer between two Products. I created Offer model and methods for making Offers:

class Offer < ActiveRecord::Base belongs_to :product belongs_to :exchanger, class_name: "Product", foreign_key: "exchanger_id" validates :product_id, :exchanger_id, presence: true def self.request(product, exchanger) unless product == exchanger or Offer.exists?(product, exchanger) transaction do create(product: product, exchanger: exchanger, status: "oczekujace") create(product: exchanger, exchanger: product, status: "oferta") end end #other methods end

Making offers is working, because I checked it in Console. My problem is in OffersController:

class OffersController < ApplicationController before_filter :setup_products def create Offer.request(@prod, @exchanger) redirect_to root_path end private def setup_products @prod = current_user.products.find(1) @exchanger = Product.find_by_id(params[:id]) end end

Problem is with a following line (using link in show-page for products with different id's than 1 works):

@prod = current_user.products.find(1)

But I don't know how to find object in Db for actual product which my show-page shows. Not only for id = 1.

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  • add error msg also.. I guess you don't have record with product id 1 for this user Commented Aug 3, 2014 at 19:00
  • do you have a product with id=1 which belongs to your current user? Commented Aug 3, 2014 at 19:02
  • With a code shown above I don't have a problem. It works. I have user with id = 1. Problem is that when i click link on my show page, my params[:id] is set on current Product id, with is ok. The second line in setup_products works. Problem is with first line. I'd like to get object for actual Product witch my page show and I don't know how to do that. I don't know how to find this object i database. Commented Aug 4, 2014 at 6:54

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9

I don't know how to find this object in database.

I don't know the specific answer to your question, but perhaps if I explain what you need to look at, your solution will arise:

Find

Rails isn't magic - it uses ActiveRecord (which is an ORM - Object-Relation Mapper), which means every time you fire a query (through find), your ORM (ActiveRecord) will search the relevant database data for you

The problem you have is that although you're using the correct syntax for your lookup, you may not have a record with an id of 1 in your db.

current_user.products.find(1) tells ActiveRecord to scope the query around the current user, and their products. So you'll get something like like this:

SELECT * FROM 'products' WHERE user_id = '15' AND id = '1'

Objects

Further, you have to remember that Ruby (and Rails by virtue of being built on Ruby) is an object orientated language. This means that everything you load / interact with in the language should be based on an object

The problem you have is you're not associating your object to your Rails framework correctly. What I mean here is described below, but essentially, if you build your Rails framework correctly, it will give you the ability to associate your objects with each other, allowing you to call the various products you need from your offer

This is a simplistic way of looking at it, of course. You'll want to look at this diagram to see how it works:

enter image description here

Bottom line - try treating your application like a series of objects, rather than a logical flow. This will help you appreciate the various associations etc that you need to get it moving forward

Resources

You mention you can't show the product on your show page for an id other than one. I think the problem is really about how to get your show action to work.

If this is the case, let me explain...

Rails is resource-based, meaning that everything you do / create needs to be centred around a resource (object) of some sort. The problem is many people don't know this, and consequently complicate their controller structure for no reason:

enter image description here

Above is the typical "CRUD" routing structure for Rails-based resources. This should demonstrate the way that Rails will typically be constructed -- around resources

--

Further, Rails is built on the MVC programming pattern - meaning you need to use your controller to populate a series of data objects for use in your application.

To this end, if you load a resource, and want to populate it with resourceful information of another object - you need to make sure you have set up the data objects in a way to ensure you can look them up correctly, which either means passing the data through your routes or using a persistent data-type, such as cookies or sessions

The problem you have is you need to pass the product id to your controller somehow. How I'd do that is as follows (using nested resources):

#config/routes.rb resources :offers do resources :products #-> domain.com/offers/2/products end

This will give you the ability to load the products controller with the variables params[:id] for the product, and params[:offer_id] for your Offer made available:

#app/controllers/products_controller.rb Class ProductsController < ApplicationController def show @offer = Offer.find params[:offer_id] @product = Product.find params[:id] end end
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