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ActiveRecord Homework for Module 4 of Turing
# 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
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