Papa Bob's Mega Solution Part 7 - Calculating the Order Price

Tutorial Series: Free C# Fundamentals via ASP.NET Web Apps

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This is the seventh part of the solution for Papa Bob's Mega Challenge. In this part, we're going to create a 'Lookup Table' to store pricing information for the different pizza options.

Step 1: Add a New Table to the Database

Navigate in the Server Explorer to the PapaBobsDbEntities database and expand it to show the folders inside. Right-click on the Tables folder and select Add > New Table:


In the table's design view, rename the table to 'PizzaPrice' and add the following properties:


Next, click 'Update' in the upper left-hand corner to commit the changes:


Right-click on the PizzaPrices table in the Server Explorer and select 'Show Table Data'. Input the following values for the current pizza prices:


Next, navigate to PapaBobsEntities.edmx within the Persistence layer. Right-click on any of the surface area not occupied by the Order model and select 'Update Model from Database...':


From the resulting dialog window, choose to add the PizzaPrices table from the database and confirm your selection:


At this point, a class called PizzaPrice should have been added to your Model next to 'Order':


Now, build your solution to ensure everything was added properly.

Step 2: Creating a PizzaPriceRepository and DTO Class

Because there is now a model for the pizza's prices, we can essentially do the reverse of what we did with the Order. Instead of passing the information to the Persistence, we can pass it from the persistence to the Domain.

To do this, we'll need to start by creating a PizzaPriceRepository class in the Persistence layer:


Then, create a new PizzaPriceDTO class within the DTO class library. Populate its properties with those found in the Entity-generated PizzaPrice class:



Step 3: Converting PizzaPrice to DTO

Returning to PizzaPriceRepository, create a new method that will retrieve the current prices for the pizza. Call this method GetPizzaPrices():


Inside this method, write the following code to retrieve the most recent prices for the pizza:


This First() method will return the first (most recent) entry in the database to the caller, setting the prices variable equal to that latest entry. Create another method beneath GetPizzPrices() to convert the PizzaPrice object to a DTO and return that new object:


Inside this method, we'll do much the same as we did in the OrderRepository when converting to an Entity; only this time converting to a DTO:


Return to the GetPizzaPrices() method, making the following changes and calling the convertToDTO() method:


Step 4: Creating a PizzaPriceManager

Now that we've saved the pizza prices into a Data Transfer Object, we can access it in the Domain layer for use in calculating the cost of the order. Because this is a separate responsibility from managing the order, we'll create a new PizzaPriceManager class. Its first responsibility will be to retrieve the pizza prices from the Persistence layer:


Then, we'll create another public method that will return the calculated pizza cost of a given order back to the caller:


This method will coordinate method calls that determine the cost for individual parts of the pizza, such as Size, Crust and Toppings, then add the returned totals together to determine the total cost. To do this, we'll need to first create a prices variable that holds the pizza prices:


Then, we'll add to the cost variable through the use of three helper methods that each take in the order and prices:


Step 5: Calculating Costs

Generate a method stub for each of the above methods to begin filling in the code logic. We'll start with the first:


Inside, we'll create a switch statement that covers all the cases for the order's Size property:


In each case, the cost variable will be assigned the value of the corresponding size cost from the list of prices:


Now, move to the calculateCrustCost() method and fill in the same swith() statement structure:


Following the same structure, assign the cost as is appropriate for each case:


Finally, we'll move our attention to the calculateToppings() method:


A switch() statement will not apply here, because each topping is its own property within the order. Instead, we can make use of ternary operators to add to the cost, like so:


Repeat this process for all the toppings in this method:


Step 6: Add the Order Price to the Order

Now that the necessary operations to calculate the price have been performed, return to the OrderManager. From here, we'll set the TotalCost property to the returned value of the PizzaPriceManager's CalculateCost() method, passing in the orderDTO:


Now, save your solution and run the project, creating an order and submitting it:


Navigate to the Orders table to see the order placed, along with its calculated total cost:



This concludes this section of the solution for Papa Bob's Mega Challenge. We've now populated every property of the order, gathered the total cost and saved it to the database. In the next part of the solution, we'll create a system for visually updating the order prices to the user.

Related Articles in this Tutorial:

Lesson 1 - Series Introduction

Lesson 2 - Installing Visual Studio 2015

Lesson 3 - Building Your First Web App

Lesson 4 - Understanding What You Just Did

Lesson 5 - Working with Projects in Visual Studio

Lesson 6 - Simple Web Page Formatting in Visual Studio

Challenge 1

Solution 1

Lesson 7 - Variables and Data Types

Lesson 8 - Data Type Conversion

Lesson 9 - Arithmetic Operators

Lesson 10 - C# Syntax Basics

Challenge 2 - ChallengeSimpleCalculator

Solution - ChallengeSimpleCalculator

Lesson 11 - Conditional If Statements

Lesson 12 - The Conditional Ternary Operator

Challenge 3 - ChallengeConditionalRadioButton

Solution - Challenge Conditional RadioButton

Lesson 13 - Comparison and Logical Operators

Lesson 13 Challenge - First Papa Bob's Website

Solution - Challenge First Papa Bob's Website

Lesson 14 - Working with Dates and Times

Lesson 15 - Working With Spans of Time

Lesson 16 - Working with the Calendar Server Control

Challenge 4 - Challenge Days Between Dates

Solution - Challenge Days Between Dates

Lesson 17 - Page_Load and Page.IsPostBack

Lesson 18 - Setting a Break Point and Debugging

Lesson 19 - Formatting Strings

Challenge 5 - Challenge Epic Spies Assignment

Solution - Challenge Epic Spies Assignment

Lesson 20 - Maintaining State with ViewState

Lesson 21 - Storing Values in Arrays

Lesson 22 - Understanding Multidimensional Arrays

Lesson 23 - Changing the Length of an Array

Challenge 6 - Challenge Epic Spies Asset Tracker

Solution - Challenge Epic Spies Asset Tracker

Lesson 24 - Understanding Variable Scope

Lesson 25 - Code Blocks and Nested If Statements

Lesson 26 - Looping with the For Iteration Statement

Challenge 7 - Challenge For Xmen Battle Count

Solution - Challenge For Xmen Battle Count

Lesson 27 - Looping with the while() & do...while() Iteration Statements

Lesson 28 - Creating and Calling Simple Helper Methods

Lesson 29 - Creating Methods with Input Parameters

Lesson 30 - Returning Values from Methods

Lesson 31 - Creating Overloaded Methods

Lesson 32 - Creating Optional Parameters

Lesson 33 - Creating Names Parameters

Lesson 34 - Creating Methods with Output Parameters

Challenge 8 - Challenge Postal Calculator Helper Methods

Solution - Challenge Postal Calculator Helper Methods

Mega Challenge Casino

Solution - Mega Challenge Casino

Lesson 35 - Manipulating Strings

Challenge 9 - Phun With Strings

Solution - Challenge Phun With Strings

Lesson 36 - Introduction to Classes and Objects

Challenge - Hero Monster Classes Part 1

Solution - Hero Monster Classes Part 1

Challenge - Hero Monster Classes Part 2

Solution - Challenge Hero Monster Classes Part 2

Lesson 37 - Creating Class Files Creating Cohesive Classes and Code Navigation

Lesson 38 - Understanding Object References and Object Lifetime

Lesson 39 - Understanding the .NET Framework and Compilation

Lesson 40 - Namespaces and Using Directives

Lesson 41 - Creating Class Libraries and Adding References to Assemblies

Lesson 42 - Accessibility Modifiers, Fields and Properties

Lesson 43 - Creating Constructor Methods

Lesson 44 - Naming Conventions for Identifiers

Lesson 45 - Static vs Instance Members

Challenge 10 - Challenge Simple Darts

Solution - Challenge Simple Darts

Lesson 46 - Working with the List Collection

Lesson 47 - Object Initializers

Lesson 48 - Collection Initializers

Lesson 49 - Working with the Dictionary Collection

Lesson 50 - Looping with the foreach Iteration Statement

Lesson 51 - Implicitly-Typed Variables with the var Keyword

Challenge 11 - Challenge Student Courses

Solution - Challenge Student Courses

Mega Challenge War

Solution - Mega Challenge War

Lesson 52 - Creating GUIDs

Lesson 53 - Working with Enumerations

Lesson 54 - Understanding the switch() Statement

Lesson 55 - First Pass at the Separation of Concerns Principle

Lesson 56 - Understanding Exception Handling

Lesson 57 - Understanding Global Exception Handling

Lesson 58 - Understanding Custom Exceptions

Lesson 59 - Creating a Database in Visual Studio

Lesson 60 - Creating an Entity Data Model

Lesson 61 - Displaying the DbSet Result in an ASP.NET GridView

Lesson 62 - Implementing a Button Command in a GridView

Lesson 63 - Using a Tools-Centric Approach to Building a Database Application

Lesson 64 - Using a Maintenance-Driven Approach to Building a Database Application

Lesson 65 - Creating a New Instance of an Entity and Persisting it to the Database

Lesson 66 - Package Management with NuGet

Lesson 67 - NuGet No-Commit Workflow

Lesson 68 - Introduction the Twitter Bootstrap CSS Framework

Lesson 69 - Mapping Enum Types to Entity Properties in the Framework Designer

Lesson 70 - Deploying the App to Microsoft Azure Web Services Web Apps

Papa Bob's Mega Challenge

Papa Bob's Mega Solution Part 1 - Setting up the Solution

Papa Bob's Mega Solution Part 2 - Adding an Order to the Database

Papa Bob's Mega Solution Part 3 - Passing an Order from the Presentation Layer

Papa Bob's Mega Solution Part 4 - Creating the Order Form

Papa Bob's Mega Solution Part 5 - Adding Enums

Papa Bob's Mega Solution Part 6 - Creating an Order with Validation

Papa Bob's Mega Solution Part 7 - Calculating the Order Price

Papa Bob's Mega Solution Part 8 - Displaying the Price to the User

Papa Bob's Mega Solution Part 9 - Creating the Order Management Page


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