Python for 循环只迭代一次

Question

基本问题，但让我很困惑。

我有一个大约 4300 行的 csv 文件。

我需要将每一行发送到一个有大小限制的服务，所以我不能一次处理所有行。

所以我的想法是有一个函数，它为 csv 文件中的每一行触发一个 for 循环。

这就是我所做的。

with open('final_result.csv') as f:
    reader = csv.reader(f)
    for row in reader:
        to_queue.append(row)

for msg in to_queue:
    # print(msg)
    def send_a_list_of_messages(sender):
        # print(to_queue)
        message = [ServiceBusMessage(str(msg))]
        sender.send_messages(message)
        print("msg sent: " + str(msg))

我对此的期望是，msg 应该以渐进方式从 csv 文件中获取每个值，将其传递给函数并发送。

在某种程度上，这就是发生的情况，但它确实只发送 csv 文件的 last 行。 我想知道我在这做错了什么？如何让这个 for 循环触发 csv 中每一行的内部函数？

编辑：

这是整个代码：

def send_a_list_of_messages(sender):
    # print(to_queue)
    message = ServiceBusMessage(str(msg))
    sender.send_messages(message)
    print("msg sent: " + str(msg))

with open('final_result.csv') as f:
    reader = csv.reader(f)
    for row in reader:
        to_queue.append(row)

for msg in to_queue:
    send_a_list_of_messages(msg)



servicebus_client = ServiceBusClient.from_connection_string(conn_str=CONNECTION_STR, logging_enable=True)
#
with servicebus_client:
    sender = servicebus_client.get_queue_sender(queue_name=QUEUE_NAME)
    with sender:
        send_a_list_of_messages(sender)

print("Done sending messages")
print("-----------------------")

with servicebus_client:
    receiver = servicebus_client.get_queue_receiver(queue_name=QUEUE_NAME, max_wait_time=5)
    with receiver:
        for msg in receiver:
            print("Received: " + str(msg))
            receiver.complete_message(msg)

该函数在 service_client 中调用

Answer 1

你需要在调用它之前定义你的函数。在您发布的示例中，您重复定义了您的函数，但没有调用它。所以，你需要定义函数，然后在循环中调用它。

编辑：我在编辑后调整了代码，您的问题似乎是在您尝试发送消息之前未为发件人分配值。

def send_a_list_of_messages(sender, msg):
    # print(to_queue)
    message = ServiceBusMessage(str(msg))
    sender.send_messages(message)
    print("msg sent: " + str(msg))

with open('final_result.csv') as f:
    reader = csv.reader(f)
    for row in reader:
        to_queue.append(row)

servicebus_client = ServiceBusClient.from_connection_string(conn_str=CONNECTION_STR, logging_enable=True)
sender = servicebus_client.get_queue_sender(queue_name=QUEUE_NAME)

for msg in to_queue:
    send_a_list_of_messages(sender, msg)

print("Done sending messages")
print("-----------------------")

receiver = servicebus_client.get_queue_receiver(queue_name=QUEUE_NAME, max_wait_time=5)
for msg in receiver:
    print("Received: " + str(msg))
    #I'm not certain what the receiver.complete_message does, but remember that you call this in a loop.
    receiver.complete_message(msg)

Answer 2

在目前的形式下，由于一些原因，它无法工作。

当您在 for 循环中重新定义函数时，它会隐藏（覆盖）该函数的前一次迭代。所以只有最终的定义存在。

您可以采取一些措施来解决此问题。

1. 直接将消息的list传递给函数：

def send_a_list_of_messages(sender, messages):
    for msg in messages:
        message = ServiceBusMessage(str(msg))
        sender.send_messages(message)
        print("msg sent: " + str(msg))

to_queue = []
with open('final_result.csv') as f:
    reader = csv.reader(f)
    for row in reader:
        to_queue.append(row)

servicebus_client = ServiceBusClient.from_connection_string(
    conn_str=CONNECTION_STR, 
    logging_enable=True
)
with servicebus_client:
    sender = servicebus_client.get_queue_sender(queue_name=QUEUE_NAME)
    with sender:
        send_a_list_of_messages(sender, to_queue)

1. 循环调用函数。

def send_a_single_message(sender, msg):
    message = ServiceBusMessage(str(msg))
    sender.send_messages(message)
    print("msg sent: " + str(msg))

to_queue = []
with open('final_result.csv') as f:
    reader = csv.reader(f)
    for row in reader:
        to_queue.append(row)

servicebus_client = ServiceBusClient.from_connection_string(
    conn_str=CONNECTION_STR, 
    logging_enable=True
)
with servicebus_client:
    sender = servicebus_client.get_queue_sender(queue_name=QUEUE_NAME)
    with sender:
        for msg in to_queue:
            send_a_single_message(sender, msg)

最好以参数的形式包含函数所需的所有内容，而不是依赖外部变量。

例如，如果您不将msg 作为参数传递，它只会在msg 在同一文件中外部定义的条件下起作用。这不会促进可重用性。