如何在 C# 中从 Google Cloud Vision 设置 GOOGLE_APPLICATION_CREDENTIALS？

Question

我正在关注 this tutorial 使用 Google Vision API，但即使配置身份验证凭据我也会收到以下错误：

System.InvalidOperationException: 'The Application Default Credentials are not available. They are available if running in Google Compute Engine. Otherwise, the environment variable GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining the credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information.'

我在 Visual Studio 2017 年的代码：

        // Instantiates a client
        var client = ImageAnnotatorClient.Create();
        // Load the image file into memory
        var image = Google.Cloud.Vision.V1.Image.FromFile(@"C:\Users\Maicon\OneDrive\Área de Trabalho\keyboardSantander\keyboard.png");
        // Performs label detection on the image file
        var response = client.DetectLabels(image);
        foreach (var annotation in response)
        {
            if (annotation.Description != null)
                debugOutput(annotation.Description);
        }

我该怎么做才能解决这个问题？我是否必须创建试用帐户才能使用 Google Cloud API？

Answer 1

这些错误消息通常在应用程序未被正确身份验证时抛出，并且可能由于多种原因而发生，例如丢失文件、无效的凭据路径、不正确的环境变量分配，除其他原因外。请记住，当您在会话中设置环境变量值时，每次会话被删除时它都会被重置。

基于此，我建议您按照 official documentation and that the file path is being correctly assigned. You can take a look on the code listed below which contains an example of the process required to authenticate your Vision API request in C# based on the Setting Up Authentication 说明验证您是否已在 GCP 项目中创建 auth 凭据 JSON 文件 :

using Google.Cloud.Vision.V1;
using System;
using Grpc.Auth;
using Google.Apis.Auth.OAuth2;

namespace VisionDemo
{
    class Program
    {   
        static void Main(string[] args)
        {
            //Authenticate to the service by using Service Account
            var credential = GoogleCredential.FromFile(@"<CRED_JSON_FILEPATH>").CreateScoped(ImageAnnotatorClient.DefaultScopes);
            var channel = new Grpc.Core.Channel(ImageAnnotatorClient.DefaultEndpoint.ToString(), credential.ToChannelCredentials());
            // Instantiates a client
            var client = ImageAnnotatorClient.Create(channel);
            var image = Image.FromFile(@"<IMAGE_FILE_PATH>");
            // Performs label detection on the image file
            var response = client.DetectLabels(image);
            foreach (var annotation in response)
            {
                if (annotation.Description != null)
                    Console.WriteLine(annotation.Description);
            }
        }
    }
}

另一方面，重要的是要考虑到 API 的使用需要有一个有效的 GCP 帐户。

最后，"The name "StorageClient“在当前上下文中不存在）”错误消息被抛出，因为您没有添加使用 Cloud Storage 和 语言服务 。请注意，这些对象是作为身份验证过程的示例添加的；但是，如果您想使用这些功能，我建议您查看以下快速入门 Storage, Natural Language.

Answer 2

以上方法我都试过了，还是不行。对我有用的是通过环境 class.

中的 SetEnvironmentVariable 添加环境变量

string credential_path = @"PATH TO GOOGLE AUTH CREDENTIAL JSON FILE";
System.Environment.SetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS", credential_path);
            
var client = ImageAnnotatorClient.Create();

var image = Image.FromFile(@"PATH TO IMAGE");
           
var response = client.DetectDocumentText(image);

如何在 C# 中从 Google Cloud Vision 设置 GOOGLE_APPLICATION_CREDENTIALS？

How to set the GOOGLE_APPLICATION_CREDENTIALS from Google Cloud Vision in C#?

c#

google-cloud-vision