Vision API Error isn't thrown

[nnegrey]

Was updating some samples and found when calling the Google Cloud Vision API with the python client library which has some handwritten helper methods making it a partial GAPIC library, that if the users passes a URL that the API can't reach, the API returns an error message, but the client library doesn't throw the error rather returns it as part of the response.

Call request: response = client.text_detection(image=image)
If you examine the response object from the api you'll find this:

error {
  code: 3
  message: "The URL does not appear to be accessible by us. Please double check or download the content and pass it in."
}

Seems like we should throw this error.

Related PR that I discovered this in: GoogleCloudPlatform/python-docs-samples#2569

[busunkim96]

It doesn't look like the handwritten layer is changing the error. I get the same result when I call batch_annotate_images directly:

from google.cloud import vision

client = vision.ImageAnnotatorClient()

source = vision.types.ImageSource(image_uri="https://bad-url")
image = vision.types.Image(source=source)
feature = vision.types.Feature(type="TEXT_DETECTION")

request = vision.types.AnnotateImageRequest(image=image, features=[feature])
response = client.batch_annotate_images(requests=[request])

responses {
  error {
    code: 14
    message: "We can not access the URL currently. Please download the content and pass it in."
  }
}

I believe this is because the API returns a Response object with an error field instead of a gRPC error. See wrap_method, wrap_errors, and _wrap_unary_errors.

The code that triggers a conversion from gRPC error to google.api_core.exceptions checks for a grpc.RpcError.

        except grpc.RpcError as exc:
            six.raise_from(exceptions.from_grpc_error(exc), exc)

I think the generator is being faithful to the proto representation of the API, but it should be possible to convert the errors at the handwritten layer if desired.

[munkhuushmgl]

@busunkim96 Let me know how I can help to resolve this issue.