Module 8: Batch and Schedule

In this module, you create and execute a batch process to send reminder emails to the conference speakers.

Step 1: Create the EmailManager class

1. In the Developer Console, click File > New > Apex Class. Specify EmailManager as the class name and click OK

2. Implement the class as follows:

   public class EmailManager {
   
       public static void sendMail(String address, String subject, String body) {
           Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
           String[] toAddresses = new String[] {address};
           mail.setToAddresses(toAddresses);
           mail.setSubject(subject);
           mail.setPlainTextBody(body);
           Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });
       }
   
   }
   

3. Click File > Save to save the file

Step 2: Create the Batch Class

1. In the Developer Console, select File > New > Apex Class, specify SendReminderEmail as the class name and click OK

2. Make the class global, implement the Batchable interface, and define the three methods of the interface:

   global class SendReminderEmail implements Database.Batchable<sObject> {
   
       global Database.QueryLocator start(Database.BatchableContext bc) {
   
       }
   
       global void execute(Database.BatchableContext bc, List<Speaker__c> scope) {
   
       }
   
       global void finish(Database.BatchableContext bc) {
   
       }
   
   }
   

3. Declare three instance variables to store the query, the email subject, and the email body:

   global String query;
   global String subject;
   global String body;
   

4. Define a constructor implemented as follows:

   global SendReminderEmail(String query, String subject, String body) {
       this.query = query;
       this.subject = subject;
       this.body = body;
   }
   

5. Implement the start() method as follows:

   global Database.QueryLocator start(Database.BatchableContext bc) {
       return Database.getQueryLocator(query);
   }
   

6. Implement the execute() method as follows:

   global void execute(Database.BatchableContext bc, List<Speaker__c> scope) {
       for (Speaker__c speaker : scope) {
           EmailManager.sendMail(speaker.Email__c, this.subject, this.body);
       }
   }
   

7. Save the file.

Step 3: Run the Batch

1. Make sure you have assigned your own email address to one of the speakers

2. In the Developer Console, click Debug > Open Execute Anonymous Window

3. Type the following Apex code:

   String q = 'SELECT First_Name__c, Last_Name__c, Email__c FROM Speaker__c WHERE Email__c != null';
   SendReminderEmail batch = new SendReminderEmail(q, 'Final Reminder', 'The conference starts next Monday');
   Database.executeBatch(batch);
   

4. Click Execute

5. Check your email