How to get PartitionId in event hub triggered Azure function?

1
votes

I have an Azure Function triggered by Event Hub. I configured the function app in the host.json with a MaxBatchSize of 32. My Event Hub has 6 partitions, and I don't want an event to be processed twice.

So, I need partition ID and sequence number to identify the event uniquely. I would like to save PartitionID and SequenceNumber in my database as primary keys. My function is triggered in input with Array of EventData. Iterating on the array, I can get the SequenceNumber for each message, but I don't know how to get per PartitionID. I tried to include parameter of type PartitionContext among input parameters but it doesn't work.

Here it is my code: 

[FunctionName("EventHubTriggeredFunction")]
public static void Run([EventHubTrigger("events", Connection = "EventHubConnection")]EventData[] eventHubMessages, TraceWriter log)
{
    foreach (var message in eventHubMessages)
    {
        using (Stream stream = message.GetBodyStream())
        {
            using (StreamReader reader = new StreamReader(stream))
            {
                try
                {
                    //... do something

                    //SequenceNumber: message.SequenceNumber
                    Save(reader.ReadToEnd(), message);

                    //... do something else
                }
            }
        }
 }

How can I get PartitionID for each message processed?

1
c#azure-functionsazure-eventhub
What makes you think your message gets processed twice? Normal behavior is for message to be processed once. – Peter Bons
@PeterBons Got it. I thought a message could be processed multiple times until his expiration (1 day in my case). I'm a beginner with event hub. Thank you for clarification. – Alessio Innocenzi
That one day (we are talking about the retention, are we?) is the minimum days the message is kept. In real world I have seen them sitting there for weeks, even months – Peter Bons
You can process older messages but it requires some (manual) steps but it is not default behavior. – Peter Bons

1 Answers

3
votes

Define the EventHub trigger to include Event Metadata. Then use the receiverRuntimeInfo on the context object.

PartitionContext.RuntimeInfo.PartitionId