Azure功能：异步方法和输出参数

Question

I want to use output queue in my azure function. I get an example code from: https://docs.microsoft.com/en-us/sandbox/functions-recipes/queue-storage

[FunctionName("BasicQueueOutput")]
public static void Run([TimerTrigger("*/30 * * * * *")]TimerInfo myTimer,
                       TraceWriter log,
                       [Queue("101functionsqueue",Connection = "AzureWebJobsStorage")] out string queueMessage)
{
    log.Info("101 Azure Function Demo - Storage Queue output");

    queueMessage = DateTime.UtcNow.ToString();
}

it works fine for sync method, but in my case it's async method:

    [FunctionName("FunctionRegisterDomain")]
    public async static Task Run(
        [QueueTrigger("domain-registation", Connection = "StorageConnectionString")]DomainForRegistration queueItem,
        [Queue("domain-add-to-office365", Connection = "StorageConnectionString")]out DomainForRegistration outputQueue,
        ILogger log)

and I get an error:

Async methods cannot have ref, in or out parameters

of course, I can do it :

    [Queue("domain-add-to-office365", Connection = "StorageConnectionString")]CloudQueue outputQueue,

and then use it:

await outputQueue.AddMessageAsync(new CloudQueueMessage(JsonConvert.SerializeObject(queueItem)));

but I would like to do it with bindings to queue message

Answer 1

You are looking for IAsyncCollector<T> to change from out param to that. Instead of “out string message” you change to ICollector<string> messages or IAsyncCollector<string> and add you message to the collection in the body.