Reference Queue Trigger Message as JSON in Azure Functions Bindings

Question

I am trying to access the queue trigger message as JSON in a JavaScript Azure Functions queue binding as follows, but I get an error that "blobTrigger is not defined" every time a new queue message arrives. I can see the field in the queue message JSON, so is there a way to do this or is this just not possible?

{
  "bindings": [
    {
      "type": "queueTrigger",
      "direction": "in",
      "name": "retryTrigger",
      "queueName": "azure-webjobs-retry"
    },
    {
      "name": "myBlob",
      "type": "blob",
      "direction": "in",
      "path": "{queueTrigger.blobTrigger}"
    }
  ]
}

jeffhollan · Accepted Answer · 2019-09-19 05:40:54Z

1

I believe you can simplify it from queueTrigger.blobName to just blobName per this doc and callout on using with JS

https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-expressions-patterns#json-payloads

This assumes the queue message is a JSON payload with a property called blobName in my example

answered Sep 19, 2019 at 5:40

jeffhollan

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Roman Kiss · Accepted Answer · 2019-09-18 20:44:50Z

you should use a POCO object in the queue trigger binding, see the following example:

using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;
using System.IO;
using System.Threading.Tasks;

namespace FunctionApp13
{
    public static class Function9
    {
        [FunctionName("Function9")]
        public static async Task Run(
            [QueueTrigger("azure-webjobs-retry", Connection = "rk2018storagev2_STORAGE")]Payload myQueueItem, 
            [Blob("{ContainerName}/{BlobName}", FileAccess.Read, Connection = "rk2018storagev2_STORAGE")] string myBlobItem, 
            ILogger log)
        {
            log.LogInformation($"C# Queue trigger function processed: {myQueueItem}");

            log.LogInformation($"Blob Content: {myBlobItem}");

            await Task.CompletedTask;
        }
    }

    public class Payload
    {
        public string ContainerName { get; set; }
        public string BlobName { get; set; }

        public override string ToString()
        {
            return $"{ContainerName}/{BlobName}";
        }
    }
}

For portal:

run.csx:

using System;

public static async Task Run(Payload myQueueItem, string myBlobItem, ILogger log)
{
    log.LogInformation($"C# Queue trigger function processed: {myQueueItem}");

    log.LogInformation($"Blob Content: {myBlobItem}");

    await Task.CompletedTask;

}

public class Payload
{
    public string ContainerName { get; set; }
    public string BlobName { get; set; }

    public override string ToString()
    {
        return $"{ContainerName}/{BlobName}";
    }
}

function.json:

{
  "bindings": [
    {
      "name": "myQueueItem",
      "type": "queueTrigger",
      "direction": "in",
      "queueName": "azure-webjobs-retry",
      "connection": "rk2018storagev2_STORAGE"
    },
    {
      "type": "blob",
      "name": "myBlobItem",
      "path": "{ContainerName}/{BlobName}",
      "connection": "rk2018storagev2_STORAGE",
      "direction": "in"
    }
  ],
  "disabled": false
}

Test:

{   
   "ContainerName":"test",
   "BlobName":"abc.json"
}

The script is crashing before it gets into my code with the "blobTrigger is not defined" error.

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