completed shop-manager-challenge

app.rb

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+# # file: app.rb
+require_relative './lib/item_repository'
+require_relative './lib/order_repository'
+require_relative 'lib/database_connection'
+
+class Application
+
+  def initialize(database_name, io, item_repository, order_repository)
+    DatabaseConnection.connect(database_name)
+    @io = io
+    @item_repository = item_repository
+    @order_repository = order_repository
+  end
+
+  def run(item_repository = ItemRepository.new, order_repository = OrderRepository.new)
+    @item_repository = item_repository
+    @order_repository = order_repository
+
+    @io.puts "Welcome to the shop management program!"
+    @io.puts "What do you want to do?
+            \n1 = list all shop items\n2 = create a new item
+            \n3 = list all orders\n4 = create a new order"
+    user_choice = @io.gets.chomp
+    while true do
+      case user_choice
+        when "1"
+          @io.puts "Here is the list of all items:"
+          @item_repository.all.each do |item|
+              @io.puts "##{item.id} #{item.name} - Unit price: #{item.price} - Quantity: #{item.quantity}"
+          end
+          break
+        when "2"
+            item = Item.new
+            @io.puts "Please enter new item name."
+              item.name = @io.gets.chomp
+            @io.puts "Please enter new item price."
+              item.price = @io.gets.chomp
+            @io.puts "Please enter new item quantity."
+              item.quantity = @io.gets.chomp
+            item_repository = ItemRepository.new
+            item_repository.create(item)
+            break
+        when "3"
+          @io.puts "Here is the list of all orders:"
+          @order_repository.all.each do |order|
+              @io.puts "##{order.id} #{order.customer_name} - Date: #{order.date}"
+          end
+          break
+        when "4"
+          order = Order.new
+          @io.puts "Please enter customer name."
+            order.customer_name = @io.gets.chomp
+          @io.puts "Please enter date."
+            order.date = @io.gets.chomp
+          order_repository = OrderRepository.new
+          order_repository.create(order)
+          break
+
+
+        else
+          @io.puts "Please choose 1, 2, 3 or 4."
+          user_choice = @io.gets.chomp
+        end
+    end
+
+  end
+
+end
+
+# Don't worry too much about this if statement. It is basically saying "only
+# run the following code if this is the main file being run, instead of having
+# been required or loaded by another file.
+# If you want to learn more about __FILE__ and $0, see here: https://en.wikibooks.org/wiki/Ruby_Programming/Syntax/Variables_and_Constants#Pre-defined_Variables
+if __FILE__ == $0
+  app = Application.new(
+    'shop_manager',
+    Kernel,
+    ItemRepository.new,
+    OrderRepository.new
+  )
+  app.run
+end
+

lib/database_connection.rb

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+# file: lib/database_connection.rb
+
+require 'pg'
+
+# This class is a thin "wrapper" around the
+# PG library. We'll use it in our project to interact
+# with the database using SQL.
+
+class DatabaseConnection
+  # This method connects to PostgreSQL using the 
+  # PG gem. We connect to 127.0.0.1, and select
+  # the database name given in argument.
+  def self.connect(database_name)
+    @connection = PG.connect({ host: '127.0.0.1', dbname: database_name })
+  end
+
+  # This method executes an SQL query 
+  # on the database, providing some optional parameters
+  # (you will learn a bit later about when to provide these parameters).
+  def self.exec_params(query, params)
+    if @connection.nil?
+      raise 'DatabaseConnection.exec_params: Cannot run a SQL query as the connection to'\
+      'the database was never opened. Did you make sure to call first the method '\
+      '`DatabaseConnection.connect` in your app.rb file (or in your tests spec_helper.rb)?'
+    end
+    @connection.exec_params(query, params)
+  end
+end

lib/item.rb

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+class Item
+
+    attr_accessor :id, :name, :price, :quantity
+end

lib/item_repository.rb

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+require_relative './item'
+
+class ItemRepository
+    def all
+        # shows all items
+        sql = 'SELECT id, name, price, quantity FROM items;'
+        result = DatabaseConnection.exec_params(sql, [])
+
+        items = []
+
+        result.each do |record|
+            items << record_to_item(record)
+        end
+
+        return items
+    end
+
+    def find(id)
+        sql = 'SELECT id, name, price, quantity FROM items WHERE id = $1;'
+        sql_params = [id]
+
+        result = DatabaseConnection.exec_params(sql, sql_params)
+        record = result[0]
+
+        return record_to_item(record)
+
+    end
+
+    def create(item)
+        sql = 'INSERT INTO items
+                    (name, price, quantity)
+                    VALUES($1, $2, $3);'
+        sql_params = [item.name, item.price, item.quantity]
+
+        DatabaseConnection.exec_params(sql, sql_params)
+
+        return nil
+    end
+
+    def delete(id)
+        sql = 'DELETE FROM items
+                    WHERE id = $1;'
+        sql_params = [id]
+
+        DatabaseConnection.exec_params(sql, sql_params)
+
+        return nil
+    end
+
+    private
+
+    def record_to_item(record)
+        item = Item.new
+        item.id = record['id']
+        item.name = record['name']
+        item.price = record['price']
+        item.quantity = record['quantity']
+
+        return item
+    end
+
+
+end

lib/order.rb

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+class Order
+
+    attr_accessor :id, :customer_name, :date, :items
+    @items = []
+end

lib/order_repository.rb

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+require_relative './order'
+
+class OrderRepository
+    def all
+        sql = 'SELECT id, customer_name, date FROM orders'
+        result = DatabaseConnection.exec_params(sql, [])
+
+        orders = []
+
+        result.each do |record|
+
+            # order = Order.new
+            # order.id = record['id']
+            # order.customer_name = record['customer_name']
+            # order.date = record['date']
+
+            orders << record_to_order(record)
+        end
+
+        return orders
+    end
+
+    def find(id)
+        sql = 'SELECT id, customer_name, date FROM orders WHERE id = $1;'
+        sql_params = [id]
+
+        result = DatabaseConnection.exec_params(sql, sql_params)
+        record = result[0]
+
+        return record_to_order(record)
+
+    end
+
+    def create(order)
+        sql = 'INSERT INTO orders
+        (customer_name, date)
+        VALUES($1, $2);'
+        sql_params = [order.customer_name, order.date]
+
+        DatabaseConnection.exec_params(sql, sql_params)
+
+        return nil
+    end
+
+    def delete(id)
+        sql = 'DELETE FROM orders
+                    WHERE id = $1;'
+        sql_params = [id]
+
+        DatabaseConnection.exec_params(sql, sql_params)
+
+        return nil
+    end
+
+    def find_with_items(id)
+        sql = 'SELECT items.id, items.name, items.price
+        FROM items
+        JOIN items_orders ON items_orders.item_id = items.id
+        JOIN orders ON items_orders.order_id = orders.id
+        WHERE orders.id = $1;'
+        sql_params = [id]
+        result = DatabaseConnection.exec_params(sql, sql_params)
+    end
+
+    private
+    def record_to_order(record)
+        order = Order.new
+        order.id = record['id']
+        order.customer_name = record['customer_name']
+        order.date = record['date']
+        return order
+    end
+
+
+end