Protobuf: How to .Unpack( an Any Message in Python

[TimmKayserHere]

Hi there,

I have some trouble, unpacking an Any message from a protobuf message. Here is a description of what I did:

1. While building my Protobuf message, I generate a message based on my proprietary protocol file as follow:

# we generate our proprietary message based on our proprietary proto-file
myMessageExtension = extension_pb2.GeneralContent_Extension()
myMessageExtension.fancyID = 345
myMessageExtension.fancyProjectDescription = "All awesome!"

1. I hand-over the proprietary message to my general message, that contains the "extension" defined as Any:

# We generate a carrier message to push our proprietary message into the Any-extension of the official spec
some_any = any_pb2.Any()
some_any.Pack(myMessageExtension)

1. I attach the extension to my general message:

# Fourth, we push our proprietary message to the extension of the official standard
myMessage.extension.CopyFrom(some_any)

So far, so good.

But now I want to read the same extension:

1. I generate a local any, copy the content of the already de-serialized protobuf message in there and unpack it:

# we now get the extension out of the protobuf
some_any2 = any_pb2.Any()
some_any2.CopyFrom(myMessage_rewrite.extension)
some_any2.Unpack(extension_pb2.GeneralContent_Extension())

1. I double-check, if the some_any2 message now reflects the extension definition (very simple message with just the two attributes):

print some_any2
print "---"
print myMessage_rewrite.extension

1. ISSUE: Both prints are reflecting just the same message (see below). My web-search unveiled, that the "Unpack(" will just return a "TRUE", if it is possible to convert. But: WHERE DO I FIND THE UNPACKED message itself?

[type.googleapis.com/project.protobuf.extension.data.GeneralContent_Extension] {
  fancyID: 345
  fancyProjectDescription: "All awesome!"
}
---
[type.googleapis.com/project.protobuf.extension.data.GeneralContent_Extension] {
  fancyID: 345
  fancyProjectDescription: "All awesome!"
}

[TimmKayserHere]

Hi all,

I am still having this issue? Could anyone find a solution for that our give me a hint?

Thanks,
Timm

[anandolee]

In for 4th step, you need to create your message before unpack. Please try:

some_any2 = any_pb2.Any()
some_any2.CopyFrom(myMessage_rewrite.extension)
unpacked_msg = extension_pb2.GeneralContent_Extension())
some_any2.Unpack(unpacked_msg)

Closing it for clean up. Feel free to reopen if it is still an issue

[TimmKayserHere]

Hi Anandolee!

Thanks for the help. It now works just fine!

Best,
Timm