IoT Hub转PowerBI数据流遇InputDeserializerError问题求助

核心问题出在JSON序列化格式不合法——你的字符串字段没有被正确包裹双引号，导致PowerBI的反序列化器无法解析消息。只保留数字时能正常工作，正好验证了这点：数字类型在JSON里不需要引号，而字符串必须用双引号包裹才符合规范。

问题根源 #

你原有的MSG_TXT模板里，Bin1Grower和Bin1Variety这两个字符串字段的占位符%s没有被双引号包裹。比如如果b1grower的值是"Grower001"，原代码生成的JSON会是：

{"Bin1Load": 50,"Bin1Grower": Grower001,"Bin1Variety": Apple,...}

这种写法不符合JSON语法，PowerBI的反序列化器自然会抛出InvalidData错误。

修正后的代码方案 #

我帮你调整了JSON模板，同时修正了代码里变量名不一致的小问题（原代码定义了b1load，但格式化时误用了b1loads，会导致运行报错）：

# 修正JSON模板：给字符串字段的占位符添加双引号
MSG_TXT = "{\"Bin1Load\": %s,\"Bin1Grower\": \"%s\",\"Bin1Variety\": \"%s\",\"Bin1StatedTn\": %.2f,\"Bin1S\": %.3f,\"Bin1CalcV\": %.2f}"

def send_confirmation_callback(message, result, user_context):
    print ( "IoT Hub responded to message with status: %s" % (result) )

def iothub_client_init():
    # Create an IoT Hub client
    client = IoTHubClient(CONNECTION_STRING, PROTOCOL)
    return client

def iothub_client_telemetry_sample_run():
    try:
        client = iothub_client_init()
        print ( "IoT Hub device sending periodic messages, press Ctrl-C to exit" )
        while True:
            # Build the message with telemetry values from PLC
            b1load = comm.Read('Bin01.Content.Load')
            b1grower = comm.Read('Bin01.Content.Grower')
            b1variety = comm.Read('Bin01.Content.Variety')
            b1statedton = comm.Read('Bin01.Content.Stated_Tn')
            b1s = comm.Read('Bin01.Content.SG')
            b1calcvol = comm.Read('Bin01.Content.Calc_Vol')
            
            # 修正变量名：与前面定义的变量保持一致
            msg_txt_formatted = MSG_TXT % (b1load, b1grower, b1variety, b1statedton, b1s, b1calcvol)
            message = IoTHubMessage(msg_txt_formatted)
            # 补充发送消息的逻辑（原代码遗漏了这一步）
            client.send_event_async(message, send_confirmation_callback, None)
            time.sleep(1) # 根据业务需求调整发送间隔
    except KeyboardInterrupt:
        print ( "IoTHubClient sample stopped" )

更可靠的优化方案 #

手动拼接JSON字符串容易出现格式疏漏，推荐用Python内置的json模块来序列化数据，它会自动处理字符串引号、特殊字符转义等问题，代码也更易维护：

import json

def iothub_client_telemetry_sample_run():
    try:
        client = iothub_client_init()
        print ( "IoT Hub device sending periodic messages, press Ctrl-C to exit" )
        while True:
            # 用字典组织遥测数据，自动处理类型格式
            telemetry_data = {
                "Bin1Load": comm.Read('Bin01.Content.Load'),
                "Bin1Grower": comm.Read('Bin01.Content.Grower'),
                "Bin1Variety": comm.Read('Bin01.Content.Variety'),
                "Bin1StatedTn": round(comm.Read('Bin01.Content.Stated_Tn'), 2),
                "Bin1S": round(comm.Read('Bin01.Content.SG'), 3),
                "Bin1CalcV": round(comm.Read('Bin01.Content.Calc_Vol'), 2)
            }
            # 序列化JSON，自动处理格式合规性
            msg_txt_formatted = json.dumps(telemetry_data)
            message = IoTHubMessage(msg_txt_formatted)
            client.send_event_async(message, send_confirmation_callback, None)
            time.sleep(1)
    except KeyboardInterrupt:
        print ( "IoTHubClient sample stopped" )

内容的提问来源于stack exchange，提问作者RedGhost