Book Image

Apex Design Patterns

By : Anshul Verma, Jitendra Zaa
Book Image

Apex Design Patterns

By: Anshul Verma, Jitendra Zaa

Overview of this book

Apex is an on-demand programming language providing a complete set of features for building business applications – including data models and objects to manage data. Apex being a proprietor programming language from Salesforce to be worked with multi tenant environment is a lot different than traditional OOPs languages like Java and C#. It acts as a workflow engine for managing collaboration of the data between users, a user interface model to handle forms and other interactions, and a SOAP API for programmatic access and integration. Apex Design Patterns gives you an insight to several problematic situations that can arise while developing on Force.com platform and the usage of Design patterns to solve them. Packed with real life examples, it gives you a walkthrough from learning design patterns that Apex can offer us, to implementing the appropriate ones in your own application. Furthermore, we learn about the creational patterns that deal with object creation mechanism and structural patterns that helps to identify the relationship between entities. Also, the behavioural and concurrency patterns are put forward explaining the communication between objects and multi-threaded programming paradigm respectively. We later on, deal with the issues regarding structuring of classes, instantiating or how to give a dynamic behaviour at a runtime, with the help of anti-patterns. We learn the basic OOPs principal in polymorphic and modular way to enhance its capability. Also, best practices of writing Apex code are explained to differentiate between the implementation of appropriate patterns. This book will also explain some unique patterns that could be applied to get around governor limits. By the end of this book, you will be a maestro in developing your applications on Force.com for Salesforce
Table of Contents (12 chapters)
Apex Design Patterns
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface

The composite pattern


Universal Call Center recently started providing customer support for online retail businesses. It is required to track details of products shipped in any order consignment. One order can have multiple products. Developers came up with the following simple Apex class:

public class Product{ 
  public String universalProductCode { get; set; } 
  public Decimal cost { get; set; } 
}

The preceding class stores the required information about one product. One order can have multiple products, so we need one more class to represent an order, as shown in the following code:

public class Order{ 
    public List<Product > lstProducts {get; set; } 
    /** 
     * Total products one Order
     * */ 
    public integer totalProducts() { 
        if(lstProducts != null) 
            return lstProducts.size(); 
         
        return 0; 
    } 
     
    /** 
     * Total cost of Order 
     * */ 
    public Decimal totalCost(){ 
        Decimal cost = 0; 
         
      ...