Azure function with additional input data parameter binding

Question

I am trying to create an Azure Function with a ServiceBus Queue trigger and an additional input data. That is the function should trigger on blob update giving the blob name as input. I want to have a Blob data as an additional input.

The function.json created is as below.

{
  "bindings": [
    {
      "name": "myQueueItem",
      "type": "serviceBusTrigger",
      "direction": "in",
      "queueName": "afqueue",
      "connection": "CONNECTIONSTRING",
      "accessRights": "Listen"
    },
    {
      "type": "blob",
      "name": "inputBlob",
      "path": "samplecontainer/{name}",
      "connection": "AzureWebJobsDashboard",
      "direction": "in"
    }
  ],
  "disabled": false
}

The function signature defined is as follows.

public static void Run(string myQueueItem, Stream inputBlob, TraceWriter log){}

This gives an error as below

Function ($ServiceBusQueueTriggerCSharp1) Error: Microsoft.Azure.WebJobs.Host: Error indexing method 'Functions.ServiceBusQueueTriggerCSharp1'. Microsoft.Azure.WebJobs.Host: No binding parameter exists for 'name'.

Instead of paramter {name}, if a hardcoded value is given the function is working properly. How to do the binding to input data variable.

Mikhail Shilkov · Accepted Answer · 2017-11-14 06:58:00Z

1

Input binding can be templated from trigger parameters. So, name should be part of your service bus message payload. You could implement the function like this:

public class MyQueueItem
{
    public string name { get; set; }
}

public static void Run(MyQueueItem myQueueItem, Stream inputBlob, TraceWriter log)
{}

Note that the only trigger for this function are Service Bus messages. The function will NOT be triggered by blob updates, unless some other code of yours sends a Service Bus message with blob name for each update in the system.

answered Nov 14, 2017 at 6:58

Mikhail Shilkov

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3 Comments

TutuGeorge Over a year ago

Cheers! This worked. I could not find enough documentation on this.

Alex Gordon Over a year ago

unless some other code of yours sends a Service Bus message with blob name for each update in the system - when it comes to storage queues, my experience has been that regardless of the type of the message received - even when specifying a strongly-typed object, such as you do with MyQueueItem - the trigger still fires! do you disagree?

Mikhail Shilkov Over a year ago

Not sure how your question about storage queue is related to my answer

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