Azure IoT 中心、EventHub 和函数 [英] Azure IoT Hub, EventHub and Functions

问题描述

我有一个带有 route 指向触发函数的 EventHub.

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

我在从事件对象获取 DeviceId 和其他 IoT 中心属性时遇到问题，而没有将它们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}");
}

我只获取负载，没有任何其他 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:

I tried to set the type to EventData instead:

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 中心属性:Properties 和 SystemProperties.例如，我可以像 iotMessage.SystemProperties["iothub-connection-device-id"] 那样访问 DeviceId.但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.

那么如何访问 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

我遗漏了 EventData 文档中的一件事.它有一个名为 GetBytes() 的方法，并将正文作为字节数组返回.获取 IoT 中心属性和正文的示例:

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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