具有事件中心输出绑定的Azure功能不起作用 [英] Azure Function with Event Hub out binding does not work

问题描述

我正在使用Azure Function将消息发送到多个事件中心输出(从输入EH).我的代码如下:

I am using Azure Function to send out message to multiple Event Hub outputs (from an input EH). My code is the following:

[FunctionName("Gateway")]
    public static void Run([EventHubTrigger("%INPUT_HUB_NAME%", Connection = "iothubconnection", ConsumerGroup = "functiontest")]EventData[] eventHubMessage,
        [EventHub("%OUT_HUB_NAME%", Connection = "eventhuboutput")]out EventData outputEventHubMessageHotPath,
        [EventHub("%OUT_HUB_NAME%", Connection = "eventhuboutput2")]out EventData outputEventHubMessageColdPath,
        TraceWriter log)
    {
        log.Info("**-- Start Azure Func -- **");


        foreach (var ehMsg in eventHubMessage)
        {
            //section to build up the raw section
            var rawMessageSection = GetPayload(ehMsg.GetBytes());
            var deviceId = GetDeviceId(ehMsg);
            log.Info($"Extracted deviceId: {deviceId}");
            if (rawMessageSection.aggregates != null)
            {
                var message = CreateEHMessages("aggregates", rawMessageSection, deviceId, log);

                outputEventHubMessageHotPath = message;
                outputEventHubMessageColdPath = message;
            }
            if (rawMessageSection.events != null)
            {
                outputEventHubMessageColdPath = CreateEHMessages("events", rawMessageSection, deviceId,  log);
            }
            if (rawMessageSection.ipis != null)
            {
                outputEventHubMessageColdPath = CreateEHMessages("ipis", rawMessageSection, deviceId, log);
            }
            if (rawMessageSection.errors != null)
            {
                outputEventHubMessageColdPath = CreateEHMessages("errors", rawMessageSection, deviceId,  log);
            }
            if (rawMessageSection.batteries != null)
            {
                outputEventHubMessageColdPath = CreateEHMessages("batteries", rawMessageSection, deviceId,  log);
            }
            //await Task.WhenAll(tasks);
        }
        outputEventHubMessageHotPath = outputEventHubMessageColdPath = null;
    }

其中:

 public static EventData CreateEHMessages(string messageType, dynamic messageBatch, string deviceId, TraceWriter log)
    {
       var timezone = messageBatch.timezone;
        var deviceInstanceId = messageBatch.deviceInstanceId;
        int i = 0;
        List<dynamic> result = new List<dynamic>();
        foreach (var msg in messageBatch[messageType])
        {

            msg.deviceId = deviceId;
            msg.timezone = timezone;
            msg.deviceInstanceId = deviceInstanceId;
            msg.type = messageType;

            result.Add(msg);
            i++;
        }
        var eventData = new EventData(Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(result)));
        eventData.PartitionKey = deviceInstanceId;
        return eventData;


    }

问题在于此函数似乎未发布到EventHub.我试图使用不同的绑定语法，但是我无法使其正常工作. 我怀疑这与输出绑定有关，但我再次尝试了许多选项. 有什么主意吗?

The problem is that this Function does NOT seem to publish to EventHub. I have tried to use different syntax of binding but i cannot get it to work. I suspect is something to do with output bindings but I again tried many options. Any idea?

推荐答案

您多次设置了out参数，因此除最后一个分配以外的所有分配都将丢失.但是最后一次分配是将它们设置为null，这实际上意味着您没有从函数中返回任何消息.

You set out parameter multiple times, so all but the last assignments will be lost. But your last assignment is setting them to null, which essentially means you return no messages from your Function.

请改为查看ICollector.

将输出参数定义为收集器:

Define your output parameters as Collectors:

[EventHub("%OUT_HUB_NAME%", Connection = "eventhuboutput")] 
ICollector<EventData> outputEventHubMessageHotPath,

然后将每封邮件添加到收集器，例如:

Then add every message to the Collectors, e.g.:

if (rawMessageSection.events != null)
{
    outputEventHubMessageHotPath.Add(
        CreateEHMessages("events", rawMessageSection, deviceId,  log));
}

这篇关于具有事件中心输出绑定的Azure功能不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！