Odtnhj

I have a quick question about displaying a has many through associations.

I have the below associations set up in 3 different models

assignment.rb 
class Assignment < ApplicationRecord
 belongs_to :stock
 belongs_to :portfolio
end

portfolio.rb
class Portfolio < ApplicationRecord
 has_many :assignments
 has_many :stocks, through: :assignments
 accepts_nested_attributes_for :stocks
end

stock.rb
class Stock < ApplicationRecord
 has_many :assignments
 has_many :portfolios, through: :assignments
end

and what i am trying to do is display all the stocks that a portfolio has on the portfolio index page after you assign a stock to a portfolio

I currently have this in my portfolio index view

<% @portfolios.stocks.each do |a|%>
 <p><%= a.ticker %></p>
<%end%>

but i am getting the below error

undefined method `stocks' for #<Portfolio::ActiveRecord_Relation:0x51f0fd8>

i don't understand what i am doing wrong

An ActiveRecord::Relation is an array like object containing several records. In your case Portfolio instances.

To call instance methods on the records (like #stocks) you need to iterate through the collection:

<% @portfolios.each do |portfolio|%>
<div class="portfolio">
 <% portfolio.stocks.each do |stock| %>
 <p><%= stock.ticker %></p>
 <% end %>
</div>
<% end %>

When doing this make sure to use .includes or .eager_load to avoid a N+1 query:

def index
 @portfolios = Portfolio.includes(:stocks).all
end

Here you've defined that you've a many to many relationship between portfolios and stocks.

which means for every porfolio you've multiple records of stocks.

So, to get all the stocks related to a portfolio you'll have to use some_porfolio.stocks

your code is not working because you're using an array of active_record and you are asking it to fetch stocks for all the portfolios in one go but relationship is not between array of active_records and array of active_records. Instead it's between a single active_record holding foreign_key of another active record.

If you want to show a list of stocks against the record of a portfolio then it's better to use

<% @portfolios.each do |porfolio| %>
 <!--- your html code for each portfolio -->
 ID: <%= portfolio.id %>
 <!--- your html code for each stock associated to this portfolio -->
 <% portfolio.stocks.each do |stock| %>
 <!--- your html code for each stock -->
 ID: <%= stock.id %>
 <% end %> 
<% end %>