c# - 从 Azure 计算机视觉 API 提取文本时出错

Question

我正在测试 Azure 计算机视觉 API，以尝试从本地 .jpg 文件中提取手写文本。我正在遵循以下示例:https://learn.microsoft.com/en-us/azure/cognitive-services/computer-vision/quickstarts-sdk/csharp-sdk

不幸的是，当我运行代码时，抛出异常:System.AggregateException:“this.Endpoint”不能为空

我当前的测试代码:

class Program
    {
        static string subscriptionKey = Environment.GetEnvironmentVariable("{SUBSCRIPTION-KEY}");
        static string endpoint = Environment.GetEnvironmentVariable("https://{MY-ENDPOINT}.cognitiveservices.azure.com/");

        private const string EXTRACT_TEXT_LOCAL_IMAGE = "vision3.jpg";

        public static ComputerVisionClient Authenticate(string endpoint, string key)
        {
            ComputerVisionClient client =
                new ComputerVisionClient(new ApiKeyServiceClientCredentials(key))
                { Endpoint = endpoint };
            return client;
        }


        static void Main()
        {
            Console.WriteLine("Azure Cognitive Services Computer Vision - .NET quickstart example");
            Console.WriteLine();

            ComputerVisionClient client = Authenticate(endpoint, subscriptionKey);

            //ExtractTextUrl(client, EXTRACT_TEXT_URL_IMAGE).Wait();
            ExtractTextLocal(client, EXTRACT_TEXT_LOCAL_IMAGE).Wait();


        }
        public static async Task ExtractTextLocal(ComputerVisionClient client, string localImage)
        {
            Console.WriteLine("----------------------------------------------------------");
            Console.WriteLine("EXTRACT TEXT - LOCAL IMAGE");
            Console.WriteLine();

            // Helps calucalte starting index to retrieve operation ID
            const int numberOfCharsInOperationId = 36;

            Console.WriteLine($"Extracting text from local image {Path.GetFileName(localImage)}...");
            Console.WriteLine();
            using (Stream imageStream = File.OpenRead(localImage))
            {
                // Read the text from the local image
                BatchReadFileInStreamHeaders localFileTextHeaders = await client.BatchReadFileInStreamAsync(imageStream);
                // Get the operation location (operation ID)
                string operationLocation = localFileTextHeaders.OperationLocation;

                // Retrieve the URI where the recognized text will be stored from the Operation-Location header.
                string operationId = operationLocation.Substring(operationLocation.Length - numberOfCharsInOperationId);

                // Extract text, wait for it to complete.
                int i = 0;
                int maxRetries = 10;
                ReadOperationResult results;
                do
                {
                    results = await client.GetReadOperationResultAsync(operationId);
                    Console.WriteLine("Server status: {0}, waiting {1} seconds...", results.Status, i);
                    await Task.Delay(1000);
                    if (maxRetries == 9)
                    {
                        Console.WriteLine("Server timed out.");
                    }
                }
                while ((results.Status == TextOperationStatusCodes.Running ||
                        results.Status == TextOperationStatusCodes.NotStarted) && i++ < maxRetries);

                // Display the found text.
                Console.WriteLine();
                var textRecognitionLocalFileResults = results.RecognitionResults;
                foreach (TextRecognitionResult recResult in textRecognitionLocalFileResults)
                {
                    foreach (Line line in recResult.Lines)
                    {
                        Console.WriteLine(line.Text);
                    }
                }
                Console.WriteLine();
            }
        }
    }

编辑:

从尝试调试来看，尽管我立即初始化了它们，但 subscriptionKey 和端点变量似乎从一开始就为空。这是为什么？

编辑2:

当我在 Main() 中对 subscriptionKey 和端点进行硬编码时:

ComputerVisionClient client = Authenticate("https://{END-POINT}.cognitiveservices.azure.com/", "{SUBSCRIPTION-KEY}");

效果很好。谁能告诉我为什么我的 2 个静态字符串变量不起作用？因为我不想对这些变量进行硬编码

Answer 1

不确定您希望这两行代码完成什么 -

static string subscriptionKey = Environment.GetEnvironmentVariable("{SUBSCRIPTION-KEY}");
static string endpoint = Environment.GetEnvironmentVariable("https://{MY-ENDPOINT}.cognitiveservices.azure.com/");

您要么选择环境变量，要么分配字符串文字，您试图...将两者结合起来？

也许可以从 appsettings.json 读取这些 secret 。