使用 ASP.NET Core web API 将图像上传到 Cloudianary 时出现空文件错误

Question

我在使用 ASP.NET Core Web API 将图像上传到 Cloudinary 时遇到问题。上传到 Cloudinary 的方法使用 IFormFile 接收图像，然后将其复制到流中。然后我的 Cloudinary Upload 方法被配置为将图像上传到 Cloudinary 但是当调用上传方法时我得到一个错误，空文件。这是我的代码。

public class CloudinaryAPI
{
    private readonly Cloudinary cloudinary;

    /// <summary>
    /// Set up cloudinary account 
    /// </summary>
    /// <param name="cloud">Cloud name</param>
    /// <param name="apiKey">API Key</param>
    /// <param name="apiSecret">API Secret</param>
    public CloudinaryAPI(string cloud = "", 
        string apiKey = "", string apiSecret = "")
    {
        Account account = new Account
        {
            Cloud = cloud,
            ApiKey = apiKey,
            ApiSecret = apiSecret
        };

        this.cloudinary = new Cloudinary(account);
    }

    /// <summary>
    /// Upload image using a Stream
    /// </summary>
    /// <param name="tream"></param>
    /// <returns></returns>
    public async Task<ImageUploadResult> UploadImage(Stream stream)
    {
        if(stream != null)
        {
            var uploadParams = new ImageUploadParams()
            {
                File = new FileDescription(Guid.NewGuid().ToString(), stream)
            };
            var uploadResult = await cloudinary.UploadAsync(uploadParams);
            return uploadResult;
        }
        throw new ArgumentNullException(message: "Something went wrong while trying to process image", null);
    }
}

这是接收请求的控制器动作。

    public async Task<IActionResult> UpdateProfilePicture(IFormFile 
    fileUpload)
    {
        using (Stream stream = new MemoryStream())
        {
            stream.Flush();
            stream.Position = 0;
            await fileUpload.CopyToAsync(stream);

            // Upload the file if less than 500KB

            if (stream.Length < 524288)
            {
                // Upload image to cloudinary
                await cloudinary.UploadImage(stream);
            }

Answer 1

这是常见错误。您需要从 FromForm 获取文件。所以你需要通过表单发送文件到后台。

 public async Task<IActionResult> UpdateProfilePicture([FromForm] IFormFile fileUpload)
 { ... }

Answer 2

我发现我必须在从 IFormFile 复制流后重置它的位置。

public async Task<IActionResult> UpdateProfilePicture(IFormFile 
fileUpload)
{
    using (Stream stream = new MemoryStream())
    {
        stream.Flush();
        await fileUpload.CopyToAsync(stream);
        stream.Position = 0;

在将文件复制到流后stream.Position应设置为0。

使用 ASP.NET Core web API 将图像上传到 Cloudianary 时出现空文件错误

Empty File error while uploading images to Cloudianary using ASP.NET Core web API

image

asp.net-core

asp.net-core-webapi

cloudinary