CODEWITHSUNDEEP
ruby-on-railsassociationsruby-on-rails-5
marcamillion
marcamillion

Reputation: 33755

How do I setup this has_many association?

So I have a PortStock model, that has action: buy and action: sell enum attributes. Each PortStock can be either position: open or position: closed (also enum values).

However, what closes one PortStock is another PortStock (i.e. a PortStock.sell closes a PortStock.buy).

So I created a join model called ClosedPositions, and basically what I want to do is record the meta-data around the closing of one PortStock by the other.

This is the schema & model for my ClosedPosition.rb model:

# == Schema Information
#
# Table name: closed_positions
#
#  id             :bigint(8)        not null, primary key
#  closer_id      :integer
#  closed_id      :integer
#  num_units      :integer
#  closed_price   :float
#  dollar_change  :float
#  percent_change :float
#  ticker         :string
#  created_at     :datetime         not null
#  updated_at     :datetime         not null
#

class ClosedPosition < ApplicationRecord
  belongs_to :closer, class_name: "PortStock", foreign_key: "closer_id"
  belongs_to :closed, class_name: "PortStock", foreign_key: "closed_id" 
end

On my PortStock model, I have a simple has_many :closed_positions.

However, when I try to add a closed_position to an existing port_stock object, I get an unknown attribute port_stock_id error.

[27] pry(main)> closer = PortStock.find(8)
  PortStock Load (0.4ms)  SELECT  "port_stocks".* FROM "port_stocks" WHERE "port_stocks"."id" = $1 LIMIT $2  [["id", 8], ["LIMIT", 1]]
=> #<PortStock:0x00007fc951a47c30
 id: 8,
 portfolio_id: 1,
 stock_id: 84,
 volume: 250,
 purchase_price: 4.1,
 current_price: 4.0,
 percent_change: -2.43902439024389,
 created_at: Tue, 12 Jun 2018 00:46:09 UTC +00:00,
 updated_at: Tue, 12 Jun 2018 00:46:09 UTC +00:00,
 current_value: 1000.0,
 dollar_change: -24.9999999999999,
 total_spend: 1025.0,
 bought_on: Sat, 09 Jun 2018 00:00:00 UTC +00:00,
 action: "sell",
 position: "open",
 ticker: "KEY">

[28] pry(main)> closed = PortStock.find(5)
  PortStock Load (0.7ms)  SELECT  "port_stocks".* FROM "port_stocks" WHERE "port_stocks"."id" = $1 LIMIT $2  [["id", 5], ["LIMIT", 1]]
=> #<PortStock:0x00007fc951a55858
 id: 5,
 portfolio_id: 1,
 stock_id: 84,
 volume: 250,
 purchase_price: 4.1,
 current_price: 4.0,
 percent_change: -2.43902439024389,
 created_at: Mon, 11 Jun 2018 03:11:10 UTC +00:00,
 updated_at: Mon, 11 Jun 2018 23:28:30 UTC +00:00,
 current_value: 1000.0,
 dollar_change: -24.9999999999999,
 total_spend: 1025.0,
 bought_on: Sat, 09 Jun 2018 00:00:00 UTC +00:00,
 action: "buy",
 position: "open",
 ticker: "KEY">

[34] pry(main)> closer.closed_positions.create(closed: closed, num_units: closer.volume, closed_price: closed.stock.price, ticker: closed.ticker)
  Stock Load (1.7ms)  SELECT  "stocks".* FROM "stocks" WHERE "stocks"."id" = $1 LIMIT $2  [["id", 84], ["LIMIT", 1]]
   (0.2ms)  BEGIN
   (0.3ms)  ROLLBACK
ActiveModel::UnknownAttributeError: unknown attribute 'port_stock_id' for ClosedPosition.
from /.rvm/rubies/ruby-2.5.1/lib/ruby/gems/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:53:in `_assign_attribute'
[35] pry(main)> closer.closed_positions.create(closed_id: closed.id, num_units: closer.volume, closed_price: closed.stock.price, ticker: closed.ticker)
   (0.2ms)  BEGIN
   (0.3ms)  ROLLBACK
ActiveModel::UnknownAttributeError: unknown attribute 'port_stock_id' for ClosedPosition.
from /.rvm/rubies/ruby-2.5.1/lib/ruby/gems/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:53:in `_assign_attribute'

How do I fix this?

Am I approaching this right? I may be messing up the association syntax & logic.

Upvotes: 0

Views: 73

Answers (2)

marcamillion
marcamillion

Reputation: 33755

What ActiveRecord was complaining about is that there was no port_stock_id column on my ClosedPosition model.

So, I simply renamed the column closed_id to port_stock_id, and then I changed my association in my ClosedPosition model from:

class ClosedPosition < ApplicationRecord
  belongs_to :closed, class_name: "PortStock", foreign_key: "closed_id" 
end

To:

class ClosedPosition < ApplicationRecord
  belongs_to :closed, class_name: "PortStock", foreign_key: "port_stock_id" 
end

Works like a charm now.

Upvotes: 0

Aniket Rao
Aniket Rao

Reputation: 778

When you are trying to create closed_positions record, ActiveRecord assumes a foreign key port_stock_id to be present which in this case is not present. So try the solution below add the has may associations. I added both (I don't know its relevance in terms of current context). This way you will be able to create associated records.

class PortStock < ApplicationRecord has_many :closed_stock_positions, foreign_key: 'closed_id', class_name: 'ClosedPosition' has_many :closer_stock_positions, foreign_key: 'closer_id', class_name: 'ClosedPosition' end

Upvotes: 1

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