Apex Triggers & Scheduler Frameworks

By Sumitkumar Shingavi

@sumit.shingavi

Agenda Design discussion on

Apex Trigger

Batches / Schedulers

Open house : Share your experience!

Twitter handlers: @sumit.shingavi @Prasanna@thisisnotapril @salesforceDevs @TheChrisDuarte@kevindrapatel

Few Questions : Apex Triggers When to use apex triggers?

When to use before / after trigger?

How many triggers you have built so far?

What is the pattern of code you have used?

What is batch size a trigger can handle when bulkified?

Do you ever seen a need to de-activate your triggers during historic data migration for enterprise scale projects?

3 ways to write Apex triggers? Modular Programming Approach – Simplest! (70%)

Factory Pattern (20%)

Abstraction of Handlers (10%)

When there are multiple handlers for a object

Sequencing of handlers is required in execution

Dynamic instance creation is required.

CustomSettings__c cs = CustomSettings__c.getInstance('Vehicle');

Type t = Type.forName(cs.className__c);

Vehicle v = (Vehicle) t.newInstance();

Apex Triggers – Keep it Simple! ONE trigger per object Logic – less triggers Context specific handler methods Use advance inline queried for loops wherever possible Right naming conventions Entry criteria – No open entry points / method calls! For Modular Programming approach, follow structure as:

AccountTrigger AccountTriggerHandler AccountTriggerActions AccountTriggerTest

For code visit: https://cloudmastro.blogspot.com

Factory & Abstraction of Handlers Factory pattern

You should have an interface which declares all handler virtual methods

Handlers are instantiated dynamically

When it actual goes down, you need to pass 1 object at a time by iterating over List<sObject>

Abstractions of handlers Also called as Dispatcher pattern

Used when you want heavy segregation between your events

Difficult to maintain

Advantages of Proposed Framework Order of execution

Separation of concerns

Control over re-entrant code

Clear organization and structure

Singleton frame

Make implementing new logic very easy

Simplify testing and maintenance

What not to do! Do not use static variables to control re-entrant code

Apex Scheduled Batch Apex : Quick Highs You can have a single class Schedulable and Batchable

Default batch size is 200 but can be raised up to 2000

It is asynchronous so no guarantee on time

100 scheduled apex jobs at a time

While writing unit tests; you should put asserts after Test.stopTest()

Governor limits applied separately for batch and schedule

10 webservice callouts per batch

Database.stateful, Apex Flex Queue (100 jobs in one shot)

Serial Batches: For this, you need to call next batch in final() method of current batch.

Thank you!

Blog: https://cloudmastro.blogspot.com

Twitter: @sumit.shingaviLinkedin: Sumitkumar Shingavi