The example of "Hello World" using pika does not mention the message's format is byte stream

[Rick Hunter]

def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)

channel.basic_consume(callback,
                      queue='hello',
                      no_ack=True)

The body parameter is a byte array actually.

When we print the body as following

print("Receive the message", body)

The output is 

Receive the message b"Test Message"

If we want to use this parameter to compare, we need convert it to str type.

bodyMessage = str(body, "utf-8") //the encoding is the message's encoding.

 Then we can compare correctly.

if bodyMessage =="xxxx":
     //do some action

[Michael Klishin]

Hi Rick,

Thank you for your feedback.

Our tutorials are open source and you are more than welcome

to contribute a change:

https://github.com/rabbitmq/rabbitmq-tutorials/

https://github.com/rabbitmq/rabbitmq-website/tree/live/site/tutorials

(note the branch I've linked to in the website repo)

One question I have is: does this work the same way for Python 2.6 and 2.7?

We can require 2.7 for the tutorials and support 3.x but it would be nice to keep 2.6

compatibility if possible.

Cheers.

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MK

Staff Software Engineer, Pivotal/RabbitMQ

[Rick Hunter]

Dear Michael,

     I have tried this example using Python 2.7.5 in CentOS 7. The input string can be received successfully.

    

   

But when I tried using Python 3.6, this problem still exists.

   

   

  

Then sender's source code is:

message = "quit"

messageProps = pika.BasicProperties()

messageProps.content_type="text/plain"

messageProps.content_encoding="utf-8"

messageProps.delivery_mode=2

channel.basic_publish(exchange="", routing_key="xxxx", body=message, properties=messageProps)

2017年6月15日星期四 UTC+8下午11:10:08，Michael Klishin写道：

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[Michael Klishin]

Hi Rick,

We'd consider a pull request that makes encoding/rendering of output values identical for

Python 2 and 3. We have to support 2.7 but ideally would like to also support 2.6.

Please see the two repos where we have tutorial code in my earlier response in this thread:

https://groups.google.com/d/msg/rabbitmq-users/08rUQg7eYeM/8nxd7B1OAgAJ.

Thank you.

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[Rick Hunter]

Dear Michael,

      I will read the tutorial code. But I still have one problem, why the byte stream can be recognized as string in Python 2, but cannot be recognized in Python 3?

在 2017年6月19日星期一 UTC+8上午11:43:34，Michael Klishin写道：

[Luke Bakken]

Rick -

This is a key difference between Python 2 and 3 and will affect much more in your Python application than just it's use of Pika.

This has a great explanation: https://docs.python.org/3/howto/pyporting.html#text-versus-binary-data

We may decide to use the value of content_encoding to decode the message payload for certain encoding values.

 

Luke

[Michael Klishin]

As Luke explains, Pika doesn't do that.

Message payloads are generally treated as opaque bags of bytes by client libraries,

as encoding details is a runtime and application-specific concern.

Generally we recommend using a data encoding library or widely used format (JSON, MsgPack,

Protocol Buffers, Kryo, and so on) instead of strings for message payloads. Those

formats will provide your payload both structure and interoperability (and in many cases,

the degree of efficiency that custom application-specific parsers may or may not achieve).

Of course, the tutorials try to explain as little as possible of those additional and system-specific

details so we use text strings in payloads.

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[Rick Hunter]

Dear Michael and Luke,

      Thank you for your explanation. I will try to use the libraries you recommended.

在 2017年6月20日星期二 UTC+8上午4:55:02，Michael Klishin写道：

As Luke explains, Pika doesn't do that.

Message payloads are generally treated as opaque bags of bytes by client libraries,

as encoding details is a runtime and application-specific concern.

Generally we recommend using a data encoding library or widely used format (JSON, MsgPack,

Protocol Buffers, Kryo, and so on) instead of strings for message payloads. Those

formats will provide your payload both structure and interoperability (and in many cases,

the degree of efficiency that custom application-specific parsers may or may not achieve).

Of course, the tutorials try to explain as little as possible of those additional and system-specific

details so we use text strings in payloads.

On Mon, Jun 19, 2017 at 4:37 PM, Luke Bakken <lba...@pivotal.io> wrote:

Rick -

This is a key difference between Python 2 and 3 and will affect much more in your Python application than just it's use of Pika.

This has a great explanation: https://docs.python.org/3/howto/pyporting.html#text-versus-binary-data

We may decide to use the value of content_encoding to decode the message payload for certain encoding values.

 

Luke

On Sunday, June 18, 2017 at 8:52:00 PM UTC-7, Rick Hunter wrote:

Dear Michael,

      I will read the tutorial code. But I still have one problem, why the byte stream can be recognized as string in Python 2, but cannot be recognized in Python 3?

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