Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
/**
* Promise v2.0 - Kevin Poorman
* Thanks to Chuck Jonas!
* This class exists to demonstrate the usage of the Promise library.
*
*/
Public Class Demo_PromiseUse {
// This execute method optionally accepts a string param that is used to pass data into
// the intial promise step.
Public Void execute(String param) {
if(String.isBlank(param)){
new Promise(new Demo_PromiseStep())
.then(new Demo_PromiseStep_Two())
.error(new Demo_PromiseError())
.done(new Demo_PromiseDone())
.execute();
} else {
new Promise(new Demo_PromiseStep())
.then(new Demo_PromiseStep_Two())
.error(new Demo_PromiseError())
.done(new Demo_PromiseDone())
.execute(param);
}
}
// This method intetntionally creates a divide by zero error so we can test handling an exception
// note that there is no error handler defined here. The .Error() method is optional. Without it, the error
// is just logged.
//
// Note! in dev and sandbox orgs the Queuable Apex queue depth is 1! as such, you're only really testing the first
// promise step. The associated test for this method, needs to have the error occur in step 2, so thats the first
// step we list.
Public Void executeWithException() {
new Promise(new Demo_PromiseStep_Two(0))
.done(new Demo_PromiseDone())
.execute();
}
// Like the previous method, this execution method is setup to cause a division by zero error in our
// Demo_PromiseStep_Two's resolve method. The constructor for that class accepts a divisor, in this
// case 0. However, this method includes an error handler. The test for this method, ensures that
// the exception handler is invoked.
Public Void executeWithExceptionWithHandler() {
new Promise(new Demo_PromiseStep_Two(0))
.error(new Demo_PromiseError())
.done(new Demo_PromiseDone())
.execute();
}
// ____ __ _ ____ _
// | _ \ ___ / _| ___ _ __ _ __ ___ __| |/ ___| | __ _ ___ ___ ___ ___
// | | | |/ _ \ |_ / _ \ '__| '__/ _ \/ _` | | | |/ _` / __/ __|/ _ \ __|
// | |_| | __/ _| __/ | | | | __/ (_| | |___| | (_| \__ \__ \ __\__ \
// |____/ \___|_| \___|_| |_| \___|\__,_|\____|_|\__,_|___/___/\___|___/
//
Public Class Demo_PromiseStep implements Promise.Deferred {
@TestVisible
Private Integer checkInteger; // helpful for testing. not generally needed.
// this is the required method for a PromiseStep class.
Public Object resolve(Object incomingObject) {
// Do some aysnchronous work, in this case, we'll pretend it's in
// our helper method:
checkInteger = exampleHelperMethod();
return checkInteger;
}
// helper methods
// I put this in a helper method not out of neccessity but because it illustrates that
// this is a normal class, and you can have multiple methods and architect this class
// in a way that code is easily testable, and isolated.
private Integer exampleHelperMethod() {
return Crypto.getRandomInteger();
}
}
Public Class Demo_PromiseStep_Two implements Promise.Deferred {
@TestVisible
Private Integer dataPassedIn;
@TestVisible
Private Integer slowAsyncWork;
Private Integer divisor;
Public Demo_PromiseStep_Two() {
}
// this constructor exists to facilitate testing. By accepting an integer
// i can later cause a division by zero error that is used to test error
// handling in the framework.
Public Demo_PromiseStep_Two(Integer divisor) {
this.divisor = divisor;
}
// This is the required interface method for a PromiseStep
Public Object resolve(Object incomingObject) {
// Do some aysnchronous work, in this case, we'll pretend it's in our helper method:
if (incomingObject != null) {
this.dataPassedIn = (Integer) incomingObject;
}
//intentionally setup to cause a divide by 0 error
if (this.divisor != null) {
Integer thrown = 1 / this.divisor;
}
slowAsyncWork = exampleHelperMethod();
return slowAsyncWork;
}
// helper methods
private Integer exampleHelperMethod() {
return Crypto.getRandomInteger();
}
}
// _ _ _ _ ____ _
// | | | | __ _ _ __ __| | | ___ _ __ / ___| | __ _ ___ ___ ___ ___
// | |_| |/ _` | '_ \ / _` | |/ _ \ '__| | | |/ _` / __/ __|/ _ \ __|
// | _ | (_| | | | | (_| | | __/ | | |___| | (_| \__ \__ \ __\__ \
// |_| |_|\__,_|_| |_|\__,_|_|\___|_| \____|_|\__,_|___/___/\___|___/
//
public class Demo_PromiseDone implements Promise.Done {
// This is used to demonstrate the use of a class instance var populated by a constructor
// Because this is an installable package i'm using an account.
@TestVisible
Private Account internalAccount;
@TestVisible
Private string completed;
// Constructors
public Demo_PromiseDone() {
} // No op constructor
public Demo_PromiseDone(Account incomingAccount) {
this.internalAccount = incomingAccount;
}
// This is the main method that the Promise.done interface requires.
// you could use this to persist a record, or to write a log.
Public Void done(Object incomingObject) {
// we could do nothing here - NOOP but we could also do something with the incomingObject
if (incomingObject != null) {
// do something here. Maybe save a record?
}
// this is a helper assignment to do testing of the library
completed = 'completed';
}
}
Public Class Demo_PromiseError implements Promise.Error {
@TestVisible
private String errorMessage;
public Demo_PromiseError() {
}
// This is the main interface method that you must implement
// note that it does have a return type, and in this case I'm using the
// promise.serializableData type. This will pass the 'error occured' string to the done handler
public Object error(Exception e) {
//for now, just dump it to the logs
system.debug('Error Handler received the following exception ' + e.getmessage() + '\n\n' + e.getStackTraceString());
//Make the error available for testing.
this.errorMessage = e.getMessage();
//Alternatively, you could do any number of things with this exception like:
// 1. retry the promise chain. For instance, if an external service returns a temp error, retry
// 1a. Use the flow control object to cap the retry's
// 2. log the error to a UI friendly reporting object or audit log
// 3. Email the error report, and related objects to the affected users
// 4. post something to chatter.
return e;
}
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.