How to serialize to json or dict that response from vision api?

[inska]

Hi,

Google Cloud SDK works well to get annotation responses via vision API, and I just like to know how can I serialize the response. Is there any helper or serializer for Google response objects? Otherwise, should I parse and build dictionaries from the response object by manual?

1. OS type and version
   OS X El Capitan
2. Python version and virtual environment information python --version
   2.7.13
3. google-cloud-python version pip show google-cloud, pip show google-<service> or pip freeze
   157.0.0
4. Stacktrace if available
5. Steps to reproduce
6. Code example

[dhermes]

@inska Can you provide a code snippet that produces the thing you'd like to serialize?

[lukesneeringer]

@inska Sadly, the objects in the current Vision library lack serialization functions (although this is a good idea).

It is worth noting that we are about to release a substantially different library for Vision (it is on master of this repo now, although not released to PyPI yet) where this will be possible. Note that it is a backwards-incompatible upgrade, so there will be some (hopefully not too much) conversion effort.

That library returns plain protobuf objects, which can be serialized to JSON using:

from google.protobuf.json_format import MessageToJson
serialized = MessageToJson(original)

You can also go to dictionaries using something like protobuf3-to-dict.

P. S. I am going to go ahead and close this issue, since I hope I have answered it, but please feel free to reopen if needed!

[arycloud]

Hi @lukesneeringer , I have tried it but it return an error like: AttributeError:'google.protobuf.pyext._message.RepeatedCompositeCo' object has no attribute 'DESCRIPTOR'
How can I resolve this error?

[u2takey]

@lukesneeringer same problem with @arycloud AttributeError:'google.protobuf.pyext._message.RepeatedCompositeCo' object has no attribute 'DESCRIPTOR'

[rootVIII]

Thanks @lukesneeringer

I can't believe how many google searches it took me to find the answer you posted.

[zyfang]

@arycloud @u2takey I had the same problem as you and I realized it's because I "unpack" the response before trying to convert it to json or dict. For example:
response = client.annotate_image({'image': {'source': {'image_uri': image_url}}, 'features': features, })
My program did the equivalent of:
MessageToJson(response.label_annotation) , which results in AttributeError:'google.protobuf.pyext._message.RepeatedCompositeCo' object has no attribute 'DESCRIPTOR'

Now I do:

response = MessageToDict(response, preserving_proto_field_name = True)
desired_res = response["label_annotation"]

[cybercser]

Thanks @lukesneeringer
I was befuddled by the same problem when working with Google Cloud Speech-to-Text API. I tried to serialize google.cloud.speech.v1.SpeechRecognitionResult, but only to find

TypeError: Object of type RepeatedCompositeFieldContainer is not JSON serializable.

I tried @lukesneeringer 's solution. It works!

[digglife]

Cool. Thank you @lukesneeringer !

[henrihe1]

Thanks @lukesneeringer

I can't believe how many google searches it took me to find the answer you posted.

Thanks a lot @lukesneeringer !
@rootVIII: I can sooo relate.

[piratezoro]

Hi @lukesneeringer I was actually using ImageAnnotatorClient with dask for parallel computation.
Until now I was just making new ImageAnnotatorClient for each image which is cause memory overflow issue. So I was planning on creating a single instance of ImageAnnotatorClient object and getting all the work done.But with dask client.map method I am unable to serialize the ImageAnnotatorClient object.So is there a way I can serialize it and the deserialize it. I tried the above method but it does not work.

[akshat-khare]

It is not working again. I am still facing this Descriptor error.

[software-dov]

All the python client libraries have been given their own repositories and no longer live under google-cloud-python. Transferring to Vision API repo.

There has been another backwards incompatible change with the Vision client library. All message types are now defined using proto-plus, which uses different methods for serialization and deserialization.

In order to get json from a message, do the following:

my_message = MyMessageType(attribute=value)

json_string = MyMessageType.to_json(my_message)
# Also works
json_string = type(my_message).to_json(my_message)
# Also also works
import proto
json_string = proto.Message.to_json(my_message)

This is not a method on the instance but instead a class method of the metaclass.