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

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

Previous Article  |  Next Article

This is the eighth part of the solution for Papa Bob's Mega Challenge. In this part, we're going to create functionality so that the order's total cost will continually be updated on the web page, and redirect the user to a success page upon creating an order.

Step 1: Creating a new EventHandler

What we need to do first is create a method that will recalculate the total cost of the order. The end goal is that this method will be called every time the user changes a selection that will affect the price.

Navigate to Default.aspx.cs and create a new recalculateTotalCost() method:



You may have noticed that this method signature is different than most that we've created, but still familiar. This is because it follows the same signature of the event handlers, such as _Click:


What we're actually creating here is a custom event handler that we'll reference in our code! This will fire off each time the selection is changed, as you'll see implemented soon.

Step 2: Refactoring the Order Creation

This recalculateTotalCost() method will need to call the Domain layer's CalculateCost() method to get the price of the order. However, remember that CalculateCost() requires an OrderDTO object. Currently, our order isn't created until the orderButton is clicked.

To remedy this problem, we can create a new helper method called buildOrder() that will create the order apart from the click event:


Cut the following code from the orderButton_Click and paste it into buildOrder():



Finally, call the buildOrder() method inside the Click event to create the order when the user clicks the button:


Step 3: Recalculating the Total Cost

Return now to the recalculateTotalCost() method. Its purpose will be to recalculate the cost whenever the user changes something that affects the price, but only when at least the size and crust are already selected. We need to create conditional statements to catch these cases before the rest of the method can begin.

What we can do in this case is create two conditional statements that will check to ensure that the SelectedValue of the DropDownListBoxes are not empty strings and, if they are, return from the method:


Then, underneath these conditional checks, build the order and pass an order object to the CalculateCost() method:


CalculateCost() returns a decimal type value. Create a new decimal variable called cost and assign it to that returned value. Then, call string.Format(), passing in that cost variable. Set the resultLabel's text to that formatted string:


Step 4: Calling recalculateTotalCost()

Now that the actual code for recalculating the cost has been written, all that's left is to call it whenever an appropriate control's value has been changed. We'll begin with the Size and Crust within Default.aspx. First of all, we need to set the value for the default selection to an empty string, ensuring that the conditional check will apply:


Next, change the OnSelectionChanged property of each DropDownList to call recalculateTotalCost() and set AutoPostBack equal to true:


Move now to the CheckBoxes and set their OnCheckChanged properties to recalculateTotalCost, and set their AutoPostBack properties to true as well:


Now, save and run your project to see the results:


Step 5: Redirecting to a Success Page

The final step in the ordering process is to redirect the user to a simple 'Success' page upon a successful order being placed. To begin, we'll need to add a new Web Form called Success.aspx to the Presentation layer:


In the Source view of this page, simply add a header with the text "Success!" for the user to see upon being redirected:


Return to Default.aspx.cs and locate the okButton_Click event. Beneath the call to CreateOrder(), write the following code to redirect the user, supplying the file name of the Success page:


Now, save and run your project to see the result upon a successful order:



This completes this portion of the solution of Papa Bob's Mega Challenge. In the next and final part of the solution, we'll create the OrderManagement page and display the orders in a GridView.

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


Please login or register to add a comment