无法在kafka python使用者中获取密钥

我已经编写了一个代码,可以在主题中以关键值的方式生成消息:

from kafka import KafkaProducer
from kafka.errors import KafkaError
import json

producer = KafkaProducer(bootstrap_servers=['localhost:9092'])

# produce json messages
producer = KafkaProducer(value_serializer=lambda m: json.dumps(m).encode('ascii'))

deviceId = "4bc03533ccc94065"
responseId = "c03c4851-701f-4265-aafd-eb133c09c08e"

print deviceId
print responseId

producer.send('collect-response-devices', {'deviceId': deviceId})
producer.send('collect-response-responses', {'responseId' : responseId})

def on_send_success(record_metadata):
    print(record_metadata.topic)
    print(record_metadata.partition)
    print(record_metadata.offset)

def on_send_error(excp):
    log.error('I am an errback', exc_info=excp)
    print excp
    # handle exception

# block until all async messages are sent
producer.flush()

# configure multiple retries
producer = KafkaProducer(retries=5)

但是,我的消费者会消费消息,不分配任何内容( None 在 key )以及价值部分的所有内容。

from kafka import KafkaConsumer
import json

consumer = KafkaConsumer(bootstrap_servers='localhost:9092', auto_offset_reset='earliest', value_deserializer=lambda m: json.loads(m.decode('utf-8')))
consumer.subscribe(['collect-response-devices'])
for message in consumer:
  print (message.key, message.value)

这是消费者的输出:

(无,u'deviceid':u'4bc03533cc94065')