谷歌.api_core.exceptions.ServiceUnavailable: 503 从插件获取元数据失败，错误为：'str'对象没有属性'before_request'。

Question

我正在尝试遍历目录中的图像，并通过google_api_vision获取它们的标签。以下是我的代码：

def run_quickstart(): import io import os import cv2 import numpy as np from google.cloud import vision from google.cloud.vision import types

client = vision.ImageAnnotatorClient(credentials = 'service_acc_key.json')

path = 'E:\wrand\\'
for image_path in os.listdir(path):

    file_name = path + image_path
    content = cv2.imread(file_name)
    # Loads the image into memory
    #with io.open(file_name, 'rb') as image_file:
       # content = image_file.read()
    content = content.tobytes()
    print(type(content))

    image = types.Image(content=content)
    print(type(image))
    response = client.label_detection(image=image)
    labels = response.label_annotations
    print('Labels:')
    for label in labels:
        print(label.description)
        # [END vision_quickstart]

if __name__ == '__main__':
    run_quickstart()

我收到的错误在代码的这个部分 image = types.Image(content=content)，完整的错误信息如下：

<class 'bytes'>
<class 'google.cloud.vision_v1.types.Image'>
ERROR:root:AuthMetadataPluginCallback " 
<google.auth.transport.grpc.AuthMetadataPlugin object at 
0x0000028520DCA2E8>" raised exception!
Traceback (most recent call last):
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site- 
packages\grpc\_plugin_wrapping.py", line 77, in __call__
    callback_state, callback))
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site- 
packages\google\auth\transport\grpc.py", line 77, in __call__
    callback(self._get_authorization_headers(context), None)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site
packages\google\auth\transport\grpc.py", line 61, in 
_get_authorization_headers
    self._credentials.before_request(
AttributeError: 'str' object has no attribute 'before_request'
Traceback (most recent call last):
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site- 
packages\google\api_core\grpc_helpers.py", line 54, in error_remapped_callable
return callable_(*args, **kwargs)
File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\grpc\_channel.py", line 487, in __call__
return _end_unary_response_blocking(state, call, False, deadline)
File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\grpc\_channel.py", line 437, in _end_unary_response_blocking
raise _Rendezvous(state, None, None, deadline)
grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with (StatusCode.UNAVAILABLE, Getting metadata from plugin failed with error: 'str' object has no attribute 'before_request')>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "Tutorial.py", line 32, in <module>
run_quickstart()
  File "Tutorial.py", line 24, in run_quickstart
response = client.label_detection(image=image)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\cloud\vision_helpers\decorators.py", line 117, in inner
response = self.annotate_image(request, retry=retry, timeout=timeout)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\cloud\vision_helpers\__init__.py", line 67, in annotate_image
r = self.batch_annotate_images([request], retry=retry, timeout=timeout)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\cloud\vision_v1\gapic\image_annotator_client.py", line 165, in batch_annotate_images
request, retry=retry, timeout=timeout, metadata=metadata)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\api_core\gapic_v1\method.py", line 139, in __call__
return wrapped_func(*args, **kwargs)
  File "C:\Users\hi_pe\AppData\Local\Programs\Python\Python36\lib\site-packages\google\api_core\grpc_helpers.py", line 56, in error_remapped_callable
six.raise_from(exceptions.from_grpc_error(exc), exc)
  File "<string>", line 3, in raise_from
google.api_core.exceptions.ServiceUnavailable: 503 Getting metadata from plugin failed with error: 'str' object has no attribute 'before_request'

我添加了一行代码 content = content.tobytes()，否则会出现这个错误 has type <class 'numpy.ndarray'>, but expected one of: ((<class 'bytes'>,),)（总是在方法调用 image = types.Image(content=content) 处）

- Stefano Pozzi

Answer 1

不幸的是，您不能直接将字符串作为凭据参数传递（尽管也许我们应该让您这样做），您应该采取以下方式：

from google.oauth2 import service_account

credentials = service_account.Credentials.from_service_account_file('service_acc_key.json')

client = vision.ImageAnnotatorClient(credentials=credentials)

- Faizan Amin

---

这真是太烦人了。这些认证流程让GC工具使用起来很难受。 - zelusp

Answer 2

在调用客户端之前，请添加以下行：

os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = path/to/service-account.json/file

- Arihant Bengani