ActiveRecord Homework for Module 4 of Turing

arctive_record_queries.rb

# Find all the items that have the word "elegant" in it.
items = Item.where("name LIKE ?", "%elegant%")

# Add three orders to a user.
  3.times do |i|
  user = User.first
  order = Order.create!(user_id: user.id)
  order.items << Item.find(i + 1)
  end
  
  users.orders.create(amount: 5)

# Given an item. Associate it with an order without touching an OrderItem model.

  # Create migration to generate the join table

  class Item < ActiveRecord::Base
    has_and_belongs_to_many :orders # Setup inverse for items model
  end

  class CreateOrders < ActiveRecord::Migration
    def change
      add_column :orders, :item_id, :integer # Add foreign key to both sides
    end
  end

  Order.create(amount: 100, user_id: 1, item_id: 1)

# Find the most popular items.
  popular = OrderItem.group(:item_id).order('count_id DESC').limit(5).count(:id)

# Find the biggest orders.
  biggest_orders = Order.order(amount: :desc).limit(5)

# Find the user who has ordered the most items.

# Find the user who has placed the most orders.
  top_buyers = Order.group(:user_id).order('count_id DESC').limit(3).count(:id)

# Find the first ten orders sorted by date created. Don't use Ruby.
  orders = Order.order(created_at: :asc).limit(10)

# Get the second ten orders sorted by date created. Don't use Ruby.
  orders = Order.order(created_at: :asc).limit(10).offset(10)

# Given a collection of orders, return a collection of the users who those orders belong to, using only one query to the database.
  orders = Order.limit(10)
  users = orders.group(:user_id)

# Given an item, find all of the users who have ordered that item.
  item = Item.first
  users = item.orders.pluck(:user_id) # => Array of user_ids

# Get the first ten users and all of their orders in one ActiveRecord query.
  users = User.includes(:orders).limit(10)

# Given a collection of items, find all of the users who have ordered that item.

# Find all of the orders created between yesterday and a month ago (you can use rand(1.year.ago..Time.now) in your seed file to spread out the dates a bit).
  orders = Order.where("created_at >= :start_date AND created_at <= :end_date",
    {start_date: 1.month.ago, end_date: 1.day.ago})

# Set it up so that when you destroy a user, ActiveRecord also destroys all of their orders
  class User < ActiveRecord::Base
    has_many :orders, dependent: :destroy
  end

  user = User.first
  user.orders.count => 5
  user.destroy

# Optional

# Get all of the orders that have more than five items. Don't use Ruby.
  Order.all.select { |order| order.items.count > 5 } # Uses Ruby :-(

# On the user model, write a method that finds the user who has the most items in common with that user