Apex 触发器入门教程

trigger TriggerName on ObjectName (trigger_events) {
   code_block
}

trigger HelloWorldTrigger on Account (before insert) {
	System.debug('Hello World!');
}

Account a = new Account(Name='Test Trigger');
insert a;

trigger HelloWorldTrigger on Account (before insert) {
    for(Account a : Trigger.new) {
        a.Description = 'New description';
    }
}

trigger ContextExampleTrigger on Account (before insert, after insert, after delete) {
    if (Trigger.isInsert) {
        if (Trigger.isBefore) {
            // Process before insert
        } else if (Trigger.isAfter) {
            // Process after insert
        }
    }
    else if (Trigger.isDelete) {
        // Process after delete
    }
}

public with sharing class CustomContactNotification {
    // Public method
    public static void notifyUsers(Set<String> recipientsIds, Integer recordCount) {
        

        // Get the ID for the custom notification type created in Setup
 		CustomNotificationType notificationType =
            [SELECT Id, DeveloperName
             FROM CustomNotificationType
             WHERE DeveloperName='New_Contact_Notification'];
        

        // Create a new custom notification
        Messaging.CustomNotification notification = new Messaging.CustomNotification();
        

        // Set the contents for the notification
        notification.setTitle('Trailhead Trigger Tutorial');
        notification.setBody(recordCount + ' contact(s) were inserted.');


        // Set the notification type and target
        notification.setNotificationTypeId(notificationType.Id);
        // '000000000000000AAA' is a dummy targetId value
        notification.setTargetId('000000000000000AAA');
        

       // Send the notification
       try {
           notification.send(recipientsIds);
           System.debug('Custom notification sent successfully.');
       }
       catch (Exception e) {
           System.debug('Problem sending notification: ' + e.getMessage());
        }
    }
}

trigger ContactNotificationTrigger on Contact (after insert, after delete) {
    if (Trigger.isInsert) {
        Integer recordCount = Trigger.new.size();
        

        // Set the recipientIDs to the current user
        Set<String> recipientIDs = new Set<String>{UserInfo.getUserId()};
      

        // Call a utility method from another class
        CustomContactNotification.notifyUsers(recipientIDs, recordCount);
    }
    else if (Trigger.isDelete) {
        // Process after delete
    }
}

Contact c = new Contact(LastName='Test Contact');
insert c;

trigger AddRelatedRecord on Account(after insert, after update) {
    List<Opportunity> oppList = new List<Opportunity>();
    // Get the related opportunities for the accounts in this trigger
    Map<Id,Account> acctsWithOpps = new Map<Id,Account>(
        [SELECT Id,(SELECT Id FROM Opportunities) FROM Account WHERE Id IN :Trigger.new]);
    // Add an opportunity for each account if it doesn't already have one.
    // Iterate through each account.
    for(Account a : Trigger.new) {
        System.debug('acctsWithOpps.get(a.Id).Opportunities.size()=' + acctsWithOpps.get(a.Id).Opportunities.size());
        // Check if the account already has a related opportunity.
        if (acctsWithOpps.get(a.Id).Opportunities.size() == 0) {
            // If it doesn't, add a default opportunity
            oppList.add(new Opportunity(Name=a.Name + ' Opportunity',
                                       StageName='Prospecting',
                                       CloseDate=System.today().addMonths(1),
                                       AccountId=a.Id));
        }
    }
    if (oppList.size() > 0) {
        insert oppList;
    }
}

trigger AccountDeletion on Account (before delete) {
    // Prevent the deletion of accounts if they have related opportunities.
    for (Account a : [SELECT Id FROM Account
                     WHERE Id IN (SELECT AccountId FROM Opportunity) AND
                     Id IN :Trigger.old]) {
        Trigger.oldMap.get(a.Id).addError(
            'Cannot delete account with related opportunities.');
    }
}

public class CalloutClass {
    @future(callout=true)
    public static void makeCallout() {
        HttpRequest request = new HttpRequest();
        // Set the endpoint URL.
        String endpoint = 'http://yourHost/yourService';
        request.setEndPoint(endpoint);
        // Set the HTTP verb to GET.
        request.setMethod('GET');
        // Send the HTTP request and get the response.
        HttpResponse response = new HTTP().send(request);
    }
}

trigger CalloutTrigger on Account (before insert, before update) {
    CalloutClass.makeCallout();
}