从 IFormFile 异常中获取内存流

Question

我上传了一张图片，想将其发送到第三方服务 (Cloudinary)，而不将文件保存在我的服务器中。

public async Task<List<string>> GetImagesUrlsByImage(IFormFile image)
{
    List<string> urlList = new List<string>();
    ImageUploadParams uploadParams = new ImageUploadParams();

    using (var memoryStream = new MemoryStream())
    {
        await image.CopyToAsync(memoryStream);
        uploadParams.File = new FileDescription(image.FileName, memoryStream);
        uploadParams.EagerTransforms = new List<Transformation>
        {
            new EagerTransformation().Width(200).Height(150).Crop("scale"),
            new EagerTransformation().Width(500).Height(200).Crop("scale")
        };

        ImageUploadResult result = await _cloudinary.UploadAsync(uploadParams);
        var url = result.SecureUrl.ToString();
        urlList.Add(url);
    }

    return urlList;
}

我没有收到异常，但来自 Cloudinary 的结果消息有一条错误消息："No image"；

调试时我看到这些错误：

我需要在此代码中修复什么？

Answer 1

最有可能的是，假设其他一切正常，您只需要在 MemoryStream:

中重置光标位置

   ms.Position = 0;

如此完整的示例：

public async Task<List<string>> GetImagesUrlsByImage(IFormFile image)
{
    List<string> urlList = new List<string>();
    ImageUploadParams uploadParams = new ImageUploadParams();

    using (var memoryStream = new MemoryStream())
    {
        await image.CopyToAsync(memoryStream);

        ms.Position = 0; // set cursor to the beginning of the stream.

        uploadParams.File = new FileDescription(image.FileName, memoryStream);
        uploadParams.EagerTransforms = new List<Transformation>
        {
            new EagerTransformation().Width(200).Height(150).Crop("scale"),
            new EagerTransformation().Width(500).Height(200).Crop("scale")
        };

        ImageUploadResult result = await _cloudinary.UploadAsync(uploadParams);
        var url = result.SecureUrl.ToString();
        urlList.Add(url);
    }

    return urlList;
}

从 IFormFile 异常中获取内存流

Get memory stream from IFormFile exceptions

c#

asp.net-core

memorystream

cloudinary