Question about Salesforce limits on API Callouts

Question

I have to call a webservice from an external system each time a new record is created on Salesforce. The external webservice accepts a single record/object instance per callout.

If I do an after-insert bulk trigger, how will I do the callouts per record? Is doing callouts in a for loop advisable?

If many records are created at the same time, will I hit the callout limits? I see only 100 callouts allowed per transaction.

Any other suggestion on this? Continuation? Queueable?

Thank you.

Answer 1

Queueable is the go-to way to do this today. You can make up to 100 callouts, then chain until you're done.

public class MyQueueable implements Database.AllowsCallouts, Queueable {
  public MyQueueable(Set<Id> recordIds) {
    this.recordIds = recordIds;
  }
  Set<Id> recordIds;
  public void execute(QueueableContext context) {
    Map<Id, sObject> records = new Map<id, sObject>([
      SELECT Fields FROM myObject__c WHERE Id = :recordIds
    ]);
    while(Limits.getCallouts() < Limits.getLimitCallouts() && recordIds.size() > 0) {
      doCalloutWith(records.get(recordids.remove(0));
    }
    if(recordIds.size() > 0) {
      System.enqueueJob(this); // Go again!
    }
  }
}

To call this:

System.enqueueJob(new MyQueueable(Trigger.newMap.keySet()));

Note that this code is future-proof; if the limits change, this code will automatically adapt to those changes.

Note also that this is a basic design, you should add error handling and retry capabilities, if necessary.