The Project | About Us | Contribute | Donations | License
HOME My courses Completed
◄ Previous
◄

Building a Simple Application

Next ►
►

In this section, we will walk through the process of building a simple RPG application. This will help you consolidate your knowledge from the previous modules and give you hands-on experience in creating a functional program. We will create a basic "Customer Management System" that allows you to add, view, and delete customer records.

Objectives

  • Understand the application requirements.
  • Design the application structure.
  • Implement the application using RPG.
  • Test the application to ensure it works as expected.

Application Requirements

Our simple Customer Management System will have the following features:

  1. Add a new customer.
  2. View all customers.
  3. Delete a customer by ID.

Designing the Application Structure

Before we start coding, let's outline the structure of our application:

  1. Data Storage: We will use a simple file to store customer records.
  2. Main Menu: A menu to navigate between different functionalities (Add, View, Delete).
  3. Functions: Separate functions for adding, viewing, and deleting customers.

Step-by-Step Implementation

Step 1: Define the Data Structure

We need to define a data structure to store customer information. Each customer will have an ID, name, and email.

Dcl-DS Customer;
  ID      Int(10);
  Name    Char(50);
  Email   Char(50);
End-DS;

Step 2: Create the Main Menu

The main menu will allow users to choose between adding, viewing, and deleting customers.

Dcl-Proc MainMenu;
  Dcl-S choice Char(1);

  Dsply 'Customer Management System';
  Dsply '1. Add Customer';
  Dsply '2. View Customers';
  Dsply '3. Delete Customer';
  Dsply 'Enter your choice: ' choice;

  Select;
    When choice = '1';
      AddCustomer();
    When choice = '2';
      ViewCustomers();
    When choice = '3';
      DeleteCustomer();
    Other;
      Dsply 'Invalid choice. Please try again.';
  EndSl;

End-Proc;

Step 3: Implement the Add Customer Function

This function will prompt the user to enter customer details and then save them to a file.

Dcl-Proc AddCustomer;
  Dcl-DS newCustomer LikeDS(Customer);
  Dcl-F customerFile Disk(*EXT) Usage(*OUTPUT);

  Dsply 'Enter Customer ID: ' newCustomer.ID;
  Dsply 'Enter Customer Name: ' newCustomer.Name;
  Dsply 'Enter Customer Email: ' newCustomer.Email;

  Write customerFile newCustomer;
  Dsply 'Customer added successfully.';

End-Proc;

Step 4: Implement the View Customers Function

This function will read and display all customer records from the file.

Dcl-Proc ViewCustomers;
  Dcl-DS customer LikeDS(Customer);
  Dcl-F customerFile Disk(*EXT) Usage(*INPUT);

  Dsply 'Customer List:';
  Read customerFile customer;
  Dow not %EOF(customerFile);
    Dsply 'ID: ' + %Char(customer.ID) + ' Name: ' + customer.Name + ' Email: ' + customer.Email;
    Read customerFile customer;
  EndDo;

End-Proc;

Step 5: Implement the Delete Customer Function

This function will delete a customer record by ID.

Dcl-Proc DeleteCustomer;
  Dcl-DS customer LikeDS(Customer);
  Dcl-S customerID Int(10);
  Dcl-F customerFile Disk(*EXT) Usage(*UPDATE);

  Dsply 'Enter Customer ID to delete: ' customerID;

  Chain customerID customerFile customer;
  If %Found(customerFile);
    Delete customerFile;
    Dsply 'Customer deleted successfully.';
  Else;
    Dsply 'Customer not found.';
  EndIf;

End-Proc;

Step 6: Putting It All Together

Finally, we need to call the MainMenu procedure to start the application.

Dcl-Proc Main;
  MainMenu();
End-Proc;

Testing the Application

  1. Add Customer: Run the application and choose the option to add a customer. Enter the details and ensure they are saved correctly.
  2. View Customers: Choose the option to view customers and verify that the added customers are displayed.
  3. Delete Customer: Choose the option to delete a customer by ID and ensure the customer is removed from the list.

Conclusion

In this section, we built a simple Customer Management System using RPG. We covered the entire process from defining data structures to implementing and testing the application. This exercise should give you a solid foundation for building more complex applications in RPG. In the next section, we will explore a more detailed case study to further enhance your skills.

◄ Previous
◄
Next ►
►
The Project | About Us | Contribute | Donations | License
© Copyright 2024. All rights reserved