Support service bus 'cardinality' setting for batches

[smolattack]

Repro steps

Provide the steps required to reproduce the problem:

1. add batchOptions host.json

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[4.*, 5.0.0)"
  },
  "extensions": {
    "serviceBus": {
      "batchOptions": { "maxMessageCount": 50 },
      "messageHandlerOptions": {
        "maxConcurrentCalls": 4
      }
    }
  },
  "concurrency": {
    "dynamicConcurrencyEnabled": true,
    "snapshotPersistenceEnabled": true
  }
}

My expectation is that my function will now be passed an array of messages but that's not the case. The following code errors as ServiceBusQueueHandler only allows for a single message.

app.serviceBusQueue("sbq", {
  connection: "SERVICEBUS",
  queueName: "msgq",
  handler(
    messages: unknown[],
    context: InvocationContext
  ) {},
  isSessionsEnabled: true,
});
});

Also, at runtime, I see only a single message rather than an array

Expected behavior

When the maxMessageCount maxMessageCount is set, I would expect the function to try to batch messages if there are more than one in the queue.

• Programming language used typscript
• Links to source
• Bindings used serviceBusQueue

[ejizba]

I just tried it myself and apparently there's a "cardinality" setting which isn't documented that needs to be set to many.

As a temporary workaround, I think this would work:

app.generic('serviceBusQueueTrigger2', {
    trigger: trigger.serviceBusQueue({
        connection: 'SERVICEBUS',
        queueName: 'msgq',
        // @ts-ignore
        cardinality: 'many',
    }),
    handler: serviceBusQueueTrigger2,
});