join tables rails postgresql
Question
I have three models: user, firm and revenue. I'd like to join the firm and revenue models, in order to publish the joined model results. Could someone please point me in the right direction on how to go about joining these tables and publish the results? Note, firm and revenue model can be joined through a unique_id number. Here is some of my code:
Revenue Model
class Revenue < ActiveRecord::Base
belongs_to :user
def self.import(file)
CSV.foreach(file.path, headers: true) do |row|
Revenue.create! row.to_hash
end
end
end
Firm Model
class Firm < ActiveRecord::Base
belongs_to :user
def self.import(file)
CSV.foreach(file.path, headers: true) do |row|
Firm.create! row.to_hash
end
end
end
User Model
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
before_save { self.email = email.downcase }
has_many :revenues
has_many :firms
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable,
:session_limitable, :confirmable
validates :name, :lastname, :industry, :company, :title, :address, :state, :city, :zip, presence: true
validates :phone, presence: true, length: { maximum: 11 }
end
Revenue DB
class CreateRevenues < ActiveRecord::Migration
def change
create_table :revenues do |t|
t.integer :unique_id
t.integer :revenue
t.integer :profit
t.references :user, index: true, foreign_key: true
t.timestamps null: false
end
end
end
Firm DB
class CreateFirms < ActiveRecord::Migration
def change
create_table :firms do |t|
t.integer :unique_id
t.string :name
t.string :state
t.string :city
t.references :user, index: true, foreign_key: true
t.timestamps null: false
end
end
end
View
<h2>Firm Data</h2>
<body>
<table>
<tr>
<th>unique_id</th>
<th>name</th>
<th>state</th>
<th>city</th>
</tr>
<body>
<% @firms.each do |firm| %>
<tr>
<td><%= firm.unique_id %> </td>
<td><%= firm.name %> </td>
<td><%= firm.state %> </td>
<td><%= firm.city %> </td>
<tr>
<% end %>
</table>
</body>
<h2>Revenue Data</h2>
<body>
<table>
<tr>
<th>unique_id</th>
<th>revenue</th>
<th>profit</th>
</tr>
<body>
<% @revenues.each do |rev| %>
<tr>
<td><%= rev.unique_id %> </td>
<td><%= rev.revenue %> </td>
<td><%= rev.profit %> </td>
<tr>
<% end %>
</table>
</body>
1 answers
solution1
2 ACCPTED 2016-08-04 14:35:04
As per your question and comments it looks right to me to set up relationships as follow:
A user has_many firms (companies). A firm has_on e revenue. A user has_many revenues through firms.
# app/models/user.rb
class User < ActiveRecord::Base
has_many :firms
has_many :revenues, through :firms
end
# app/models/firm.rb
class Firm < ActiveRecord::Base
has_one :revenue
end
# app/models/revenue.rb
class Revenue < ActiveRecord::Base
belongs_to :firm
end
Instead of storing a unique_id in both firms and revenues tables, it would be better to use a foreign_key in revenues, like firm_id .
The corresponding migrations are:
class CreateFirm < ActiveRecord::Migration
def change
create_table :firm do |t|
t.string :name
t.string :state
t.string :city
t.timestamps null: false
end
end
end
class CreateRevenue < ActiveRecord::Migration
def change
create_table :firm do |t|
t.belongs_to :firm, index: true
t.integer :revenue
t.integer :profit
t.timestamps null: false
end
end
end
This will enable you to use, for example, firm.revenue.profit to display the value of profit in the app/views/firms/show.html.erb view.
Looking at your models and migrations syntax it seems you are not using Rails 5. You can find Rails 4.2 docs about the has_one relationship here .
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