Introduction to apex code

Coding the Cloud: An Introduction
to Apex Code

Force.com Platform Fundamentals

Andrew Albert, salesforce.com

Safe Harbor Statement
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www.salesforce.com/investor. Salesforce.com, inc. assumes no obligation and does not intend to update these forward-
looking statements, except as required by law.

Andrew Albert
Technical Evangelist

Apex Code: Logic-as-a-Service

 What is it?

 What can it do?

 How do I use it?

 Well, let‟s see it!

Introducing Apex
 Force.com allows many customizations through User
Interface
 Force.com API allows developers to write client-side
programs or integrations for more flexibility in their
applications
– Client side programs have performance costs
– Lack transactional control across API requests
– Cost and complexity of client hosting server code
 APEX was introduced to address those issues and to
revolutionize the way developers create on-demand
applications.

Apex Code Is
 Strongly-typed, object-based programming language
 Enables developers to execute logic and transaction
control statements on Force.com
 Runs natively on the server
 Code executes on the server when initiated by User
Interface via Buttons & Events, and data through the
API
 Java or C#-like syntax
 Transactional

How can you use Apex Code?
 Database Trigger
- Apex Code that is executed in response to a
database interaction

Example: Apex trigger is initiated whenever a new
Contact record is inserted.

 Class
- Similar to a Java or .NET class
- A trigger can call an Apex Class

Differences between Triggers and Classes
 Triggers execute implicitly in response to a database
action
 Apex class methods can be explicitly called in many
areas of the Force.com

 For example:
(a) Email to Apex Services
(b) Apex Web Services
(c) Visualforce controllers

How is Apex Different?
 Executes directly on the Force.com
 Eliminates network traffic between client application
and Force.com
 Apex Code tightly integrated to the rest of the platform
functionality
 Changes to the metadata referenced in Apex Code will
cause an automatic recompilation the next time those
components are executed

Language Basics
Data Types – Primitive
- String
- Boolean
- Date and DateTime
- Integer, Long, Double
- ID (Force.com database record identifier)
- Blob (for storing binary data)
- Sobject (object representing a Force.com standard or custom
object)
Example:
DateTime dt = System.now() + 1;
Boolean isClosed = true;
String sCapsFirstName = „Andrew‟.toUpperCase();
Account acct = new Account(); //Sobject example

Language Basics (cont)
Data Types – Collections
- Lists
- Sets
- Maps
- Arrays

Example:
List<Integer> myList = new List<Integer>();
myList.add(12); //Add the number 12 to the list
myList.get(0); //Access to first integer stored in the List

Statements and Expressions
- If/Else
- For Loops
- Do/While Loops
- While Loops

Example:
Integer count = 0;
while(count < 11){
System.debug(„Count = „ + count);
count++;
}

Exception Handling
- Try/Catch/Finally statements
- Ability to create and throw your own Exceptions

Example:
public class OtherException extends BaseException {}
Try{
//Add code here
throw new OtherException(„Something went wrong here…‟);
} Catch (OtherException oex) {
//Caught a custom exception type here
} Catch (Exception ex){
//Caught all other exceptions here
}

Force.com Query Languages
 SOQL – Salesforce object Query Language
String myName = „Acme‟;
Account[] accts = [select ID from Account where name =:myName] //Pass in a variable

 SOSL – Salesforce object Search Language
List<List<SObject>> searchList = [FIND '415' IN PHONE FIELDS RETURNING Account, Contact ];
Account [] accounts = ((List<Account>)searchList[0]);
Contact [] contacts = ((List<Contact>)searchList[1]);

Data Manipulation with Apex
 DML (Data Manipulation Language)
- Insert
- Update
- Upsert - Operation to create a new or update existing record
based on an external id.
- Delete
- Undelete

Here’s what it looks like Interface
Implementation
Function
Declaration
1 1 global class tasks implements Messaging.InboundEmailHandler {
2 2
3 3 global Messaging.InboundEmailResult handleInboundEmail(Messaging.inboundEmail email,
4 4 Messaging.InboundEnvelope env){
5 5
6 6 // Create inboundEmailResult object for returning the result of the Force.com Email Service
7 7 Messaging.InboundEmailResult result = new Messaging.InboundEmailResult();
8 8
9 9 String myPlainText = '‟; Object
101 Instantiation
Variable Declaration
111 // Add the email plain text into the local variable
121 try {
131 myPlainText = email.plainTextBody.substring(0, email.plainTextBody.indexOf('<stop>'));
141 } catch (System.StringException e) {
151 myPlainText = email.plainTextBody; Exception
161 System.debug('No <stop> in email: ' + e); Handling
171 }
181
191 // new Task object to be created List Creation Comment
202 List<Task> newTask = new List<Task>(); Syntax
212
222 /* Try to lookup any contacts based on the email from address
232 / If there is more than 1 contact with the same email address
24 / an exception will be thrown and the catch statement will be called
25 */
262 try {
272 Contact vCon = Id, Name, Email From Contact Where Email = :email.fromAddress]
[Select
28
29 ...
Query Language

Bulk data operations with Apex
 Commonly, the ordering of process for an apex solution is as follows:
1) Records are retrieved from the Force.com database with a query
statement
2) The array of records ismodified in the processing of your Apex
Code
3) The array of records is then sent back to the object through a
data manipulation statement

These actions are performed in bulk on the Force.com

Bulk data operations with Apex (cont)

 Apex Code must be designed to handle bulk operations
 Why is this important?
- The Force.com enforces limits to how many records can be
processed at a time (governor limits)
 Examples:
 Limit on the number of records that can be queried.
 Limit on the number of records that be modified.
 Limits are calculated by the number of records invoking the Apex
Code code

Handling Bulk operations - example

Testing

 Apex Code to test your Apex Code
 Code to help developers perform and automate unit testing
 Enables the platform to execute these “test methods” during
deployment
 Force.com requires that at least 75% of your Apex is
covered by testing before code can be deployed to a
Production environment (100% is ideal!)
 Unit test methods are denoted with testMethod keyword.
 testMethods do not modify any data in your org

What can you do with Apex Code?
 Triggers
 Apex Web Services
 Email Services
 SOA (callouts)
 Visualforce Controllers

What can you do with Apex Code?
 Triggers
– Code runs when data changes to ensure business logic is
applied
– Executes on the server when data changes in either the UI or API.

 Email Services
– Send & Receive emails, including attachments, with custom
logic to process contents.
– Includes all standard email attributes, use email templates, and
supports plain text or HTML.
– Force.com generates a unique email address to process the
contents.

What else can you do with Apex Code?
 Apex Web Services
– Develop new Force.com Web Services
– Define and expose a custom Web Service for an external service
to invoke.
– As simple as adding the “webService” keyword to a Apex method
– WSDL automatically available

 Consume other Web Services
– Provides integration with external Web Services
– Apex provides integration with Web services that utilize SOAP
and WSDL, or HTTP services

What else can you do with Apex Code?
 Visualforce Controllers
– Apex logic accessed by Visualforce pages through custom
controllers and controller extensions.
– Apex Class that drives the logic when a user interacts with the
Visualforce pages.

Winter ‘09 Apex Feature – Dynamic Apex

 Streamline code design
public class displayFields{
……
//Retrieves available SObjects with Global Describe
eliminate repetitive code by
private Map <String, Schema.SObjectType> schemaMap =
Schema.getGlobalDescribe(); constructing dynamic procedures
//Retrieve accessible fields for specified object
public List<Field> showFields(String selectedObject) {
for query, search, and data
fields.clear();
Map <String, Schema.SObjectField> fieldMap = manipulation
schemaMap.get(selectedObject).getDescribe().fields.getMap();
//for each field – determine whether the running user has
access to the field
 Describe methods
for(Schema.SObjectField f : fieldMap.Values()){
Schema.DescribeFieldResult df = f.getDescribe();
if(df.isAccessible()){
New Apex methods to describe
fields.add(f);
} schema including object definition
}
return fields; and field definitions.
}

 User permission awareness
The power of system level access
with the capability to enforce user
permissions and constraints

Winter ‘09 Apex Feature – Async Apex

global class myclass {
public class MyException extends Exception{}
 Asynchronous execution
public static void throwException() {
System.debug('calling throw exception');  Supports web service callouts
throw new MyException('for bar');
} from triggers
@future(callout=true) static void voidvoid() {
System.debug('void void');  Monitoring UI provides
Http http = new Http();
HttpRequest req = new HttpRequest(); detailed view of status and
req.setMethod('GET');
req.setEndpoint('http://www.cheenath.com'); execution time
HttpResponse res = http.send(req);
System.debug(res.getBody());
//throw new MyException('for bar');
}
@future static void createAccount(String n) {
Account a = new Account(name=n);
insert a;
}

Additional Dreamforce 2008 Apex Sessions

 Apex Test Coverage Best Practices
– Tuesday, 2:00-3:00PM, Esplanade 305
 Hands-On : Apex Code
– Tuesday, 2:00-3:00PM, South 102
 Development As A Service – Building and Deploying Apps
in the Cloud
– Wednesday, 10:15-11:15AM, Esplanade 303

Force.com Library
 Books
– Developer‟s Guide to the Force.com
– Force.com Cookbook
– Creating On-Demand Apps
 Apex Language Reference

Additional Resources
 Developer.Force.com
– Force.com Developer Community
– Apex Developer Guide & Language Reference
– Recorded technical presentations and whitepapers
– Apex Message Boards

 Sign up for free Developer Edition
 Training Courses & Certification
– DEV401: Force.com essentials
– DEV501: Visualforce, Apex, DaaS (Development As A Service)

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