Creating migrations and models for database rails 4

Question

I trying to create this enter image description here

Where User is a one to many for IncomePicture and ExpensePicture and ExpensePicture and IncomePicture have a one to one relationship to IncomeText and ExpenseText. This is what I have so far. I'm a bit confused on what migration actually does? My guess is that it updates the tables in the database. I feel that I am missing a lot in my migrations to create the desired scheme in my database. I think my models are okay but I'm not quite sure. I get confused with the rails g migration ... commands. It seems like that command updates or alters the table columns

Models:

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :rememberable, :validatable

  has_many :expense_pictures 
  has_many :income_pictures

end

class IncomePicture < ActiveRecord::Base
  belongs_to :user
  mount_uploader :image, ImageUploader
  has_one :income_text
end

class IncomeText < ActiveRecord::Base
  belongs_to :income_pictures
end

class ExpensePicture < ActiveRecord::Base

  belongs_to :user
  mount_uploader :image, ImageUploader
  has_one :expense_text
end

class ExpenseText < ActiveRecord::Base
  belongs_to :expense_pictures
end

Migration

class DeviseCreateUsers < ActiveRecord::Migration
  def change
    create_table(:users) do |t|
      t.string :email,              null: false, default: ""
      t.string :encrypted_password, null: false, default: ""
      t.datetime :remember_created_at
      t.timestamps
    end

    add_index :users, :email,                unique: true
  end
end


class CreateExpensePictures < ActiveRecord::Migration
  def change
    create_table :expense_pictures do |t|
      t.timestamps
    end
  end
end


class CreateIncomePictures < ActiveRecord::Migration
  def change
    create_table :income_pictures do |t|

      t.timestamps
    end
  end
end


class AddImageToExpensePicture < ActiveRecord::Migration
  def change
    add_column :expense_pictures, :image, :string
  end
end


class AddImageToIncomePicture < ActiveRecord::Migration
  def change
    add_column :income_pictures, :image, :string
  end
end


class CreateIncomeTexts < ActiveRecord::Migration
  def change
    create_table :income_texts do |t|
      t.timestamps
    end
  end
end


class CreateExpenseTexts < ActiveRecord::Migration
  def change
    create_table :expense_texts do |t|
      t.timestamps
    end
  end
end

You should be adding the respected FKs to the tables.

Pavan
– Pavan

2014-07-20 09:47:57 +00:00
Commented Jul 20, 2014 at 9:47 — Pavan
– Pavan, Commented Jul 20, 2014 at 9:47

SteveTurczyn · Accepted Answer · 2014-07-20 11:08:17Z

1

The only thing you need to add via a migration is the foreign keys. Rails will be responsible for the associations so it'll all work after that.

class AddForeignKeysToTables < ActiveRecord::Migration
  def change
    add_column :income_pictures, :user_id, :integer
    add_column :expense_pictures, :user_id, :integer
    add_column :expense_texts, :expense_picture_id, :integer
    add_column :income_texts, :income_picture_id, :integer
  end
end

You can also do it as...

add_reference :products, :user, index: true

class AddForeignKeysToTables < ActiveRecord::Migration
  def change
    add_reference :income_pictures, :user
    add_reference :expense_pictures, :user
    add_reference :expense_texts, :expense_picture
    add_reference :income_texts, :income_picture
  end
end

and in fact you can add an index to the foreign keys...

add_reference :income_pictures, :user, index: true

edited Jul 20, 2014 at 11:08

answered Jul 20, 2014 at 10:37

SteveTurczyn

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3 Comments

SteveTurczyn Over a year ago

No, sorry, that's not right. create_table :user do |t| t.references :expense_pictures end ... that creates a link :expense_picture_id inside the users table which is not where it's needed... Remember one user can point to MANY expense_pictures... the foreign keys need to be on the "belongs_to" side.

SteveTurczyn Over a year ago

Edited my comment, sorry... premature 'Enter'. :)

SteveTurczyn Over a year ago

Edited my answer to show use of add_reference instead of add_column... but the two peform equivalent actions.

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