Azure Function Blob 存储连接 : The format of value '*' is invalid

Question

我正在编写一个 v2 Azure 函数，我将在其中访问 Azure Blob 存储。因为我遇到了麻烦，所以我将其简化为这个最小的示例。

namespace Test
{
    public static class Function1
    {
        [FunctionName("Function1")]
        public static async Task<IActionResult> Run(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "test")] HttpRequest req,
            ILogger log)
        {
            var azureStorage = CloudStorageAccount.Parse("UseDevelopmentStorage=true");
            var blobClient = azureStorage.CreateCloudBlobClient();
            var container = blobClient.GetContainerReference("migrated-load-sets-localhost");
            var blobReference = container.GetBlockBlobReference("11016093-2f6e-4631-97c1-04f8acfb2370");
            var memoryStream = new MemoryStream();
            var accessCondition = AccessCondition.GenerateIfExistsCondition();
            var blobRequestOptions = new BlobRequestOptions();
            await blobReference.DownloadToStreamAsync(memoryStream, accessCondition, blobRequestOptions, null);
            var text = System.Text.Encoding.UTF8.GetString(memoryStream.ToArray());
            return new OkObjectResult(text);
        }
    }
}

当我运行并点击这个时，我收到错误

System.Private.CoreLib: Exception while executing function: Function1. Microsoft.WindowsAzure.Storage: The format of value '*' is invalid. System.Net.Http: The format of value '*' is invalid.

如果我改变

var accessCondition = AccessCondition.GenerateIfExistsCondition();

成为

var accessCondition = AccessCondition.GenerateEmptyCondition();

它有效。

我在调试中观察到 accessCondition.IfMatchETag 等于 "*"，所以看来这可能是罪魁祸首。

我使用AccessCondition.GenerateIfExistsCondition()时是否做错了什么，或者库中是否存在错误？

Answer 1

如果您需要在下载文件之前检查 blob 是否存在，您只需要

if(blobReference.ExistsAsync())
{
   //Download
}