Azure IoT中心，EventHub和功能

问题描述

我有一个带有路由指向触发功能的EventHub.

I have an IoTHub with a route that points to an EventHub which triggers a Functions.

我无法从事件对象获取 DeviceId 和其他IoT中心属性，而没有将这些属性显式添加到有效负载中.

I'm having problem getting the DeviceId and other IoT Hub properties from the event object without adding those explicitly to the payload.

如果我将输入类型设置为string(或自定义类型):

If I set the input type to a string (or a custom type):

public static void Run(string iotMessage, TraceWriter log) {
    log.Info($"C# Event Hub trigger function processed a message: {iotMessage}");
}

我仅获得有效负载，而没有其他任何IoT中心属性，例如 DeviceId ， CorrelationId 或 MessageId .

I only get the payload without any other IoT Hub properties like DeviceId, CorrelationId or MessageId.

我尝试将类型设置为EventData:

public static void Run(EventData iotMessage, TraceWriter log) {
    log.Info($"C# Event Hub trigger function processed a message: {JsonConvert.SerializeObject(iotMessage)}");
}

现在，我可以通过两个getter访问IoT Hub属性:Properties和SystemProperties.例如，我可以像这样iotMessage.SystemProperties["iothub-connection-device-id"]访问DeviceId.但是它不会暴露有效载荷.

Now I can access the IoT Hub properties via two getters: Properties and SystemProperties. For example I can access DeviceId like this iotMessage.SystemProperties["iothub-connection-device-id"]. But it does not expose the payload.

那我该如何访问IoT中心属性和有效负载?

So how do I access both IoT Hub properties and the payload?

推荐答案

我错过了EventData文档中的任何内容.它具有一个称为GetBytes()的方法，并将主体作为字节数组返回.同时获取IoT中心属性和主体的示例:

I missed a thing in the documentation for EventData. It has a method called GetBytes() and returns the body as a byte array. Example of getting both the IoT Hub properties and the body:

public static async void Run(EventData telemetryMessage, TraceWriter log)
{
    var deviceId = GetDeviceId(telemetryMessage);
    var payload = GetPayload(telemetryMessage.GetBytes());

    log.Info($"C# Event Hub trigger function processed a message.  deviceId: { deviceId }, payload: { JsonConvert.SerializeObject(payload) }");
}

private static Payload GetPayload(byte[] body)
{
    var json = System.Text.Encoding.UTF8.GetString(body);
    return JsonConvert.DeserializeObject<Payload>(json);
}

private static string GetDeviceId(EventData message)
{
    return message.SystemProperties["iothub-connection-device-id"].ToString();
}

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