如何将谷歌客户端视觉库响应转换为 json

Question

我正在尝试将来自Google Cloud Vision API客户端库的响应转换为json格式。但是我收到以下错误：

属性错误："google.protobuf.pyext._message。RepeatedCompositeCo' 对象没有属性"描述符">

资源

from flask_restful import Resource
from flask import request
from flask import json
from util.GoogleVision import GoogleVision
from util.Convert import Convert
import base64
import requests
import os

class Vision(Resource):
def post(self):
googleVision = GoogleVision()
req = request.get_json()
url = req['url']
result = googleVision.detectLabels(url)
return result

GoogleVision.py

import os
from google.cloud import vision
from google.cloud.vision import types
from google.protobuf.json_format import MessageToJson
class GoogleVision():
def detectLabels(self, uri):
client = vision.ImageAnnotatorClient()
image = types.Image()
image.source.image_uri = uri
response = client.label_detection(image=image)
labels = response.label_annotations
res = MessageToJson(labels)
return res

标签变量的类型为<class'google.protobuf.pyext._message.RepeatedCompositeContainer'>

如您所见，我正在标签响应上使用消息到 json 函数。但是我收到上述错误。

有没有办法将结果转换为 json 格式？

Answer 1

一个简单的方法是使用发现API。您可以使用 build(( 函数创建服务对象。执行请求时，您将以字典的形式获得响应。然后，您可以使用json.dumps()将其转换为 JSON。

使用发现 API 的示例：

import json
import apiclient.discovery
import base64
class GoogleVision():
def detectLabels(self, uri):
# Instantiates a client
service = apiclient.discovery.build('vision', 'v1')
# Image file
file_name=uri
# Loads the image into memory
with open(file_name, 'rb') as image:
image_content = base64.b64encode(image.read())
# Creates the request
service_request = service.images().annotate(body={
'requests': [{
'image': {
'content': image_content.decode('UTF-8')
},
'features': [{
'type': 'LABEL_DETECTION',
}]
}]
})
# Execute the request  
response = service_request.execute()
# Convert to Json
res_json = json.dumps(response)
return res_json

如果不想使用发现 API，可以先使用MessageToDict()函数将响应转换为字典，然后再使用json.dumps()将响应转换为 JSON。

没有使用MessageToDict()的发现 API 的示例：

import json
from google.cloud import vision
from google.cloud.vision import types
from google.protobuf.json_format import MessageToDict
class GoogleVision():
def detectLabels(self, uri):
# Instantiates a client
client = vision.ImageAnnotatorClient()
# Image file
file_name=uri
# Loads the image into memory
with open(file_name, 'rb') as image:
image_content = image.read()
image = types.Image(content=image_content)
# Performs label detection on the image file
response = client.label_detection(image=image)       
#Convert the response to dictionary
response = MessageToDict(response)
# Convert to Json
res_json = json.dumps(response)
return res_json