In ASP.NET Core-6 Web API application, I am trying to upload multiple files. I have this code

File Type Validation

public static bool CheckIfPdfFile(IFormFile file)
{
    var extension = "."   file.FileName.Split('.')[file.FileName.Split('.').Length - 1];
    return (extension == ".pdf"); 
}

public class AdminFileModel
{
    public List<IFormFile> MyFile { get; set; }
}

Model:

public class MandateApprovalAttachment
{
    public Guid Id { get; set; }
    public string FileType { get; set; }
    public string FileName { get; set; }
    public string FilePath { get; set; }
    public long? FileSize { get; set; }
    public string MimeType { get; set; }
}

Then the main method that will perform the operation:

public async Task<Response<string>> MandateApproval(AdminFileModel model)
{
    var response = new Response<string>();
    string fileName = "";
    try
    {
            if (model.MyFile == null || model.MyFile.Count == 0)
            {
                response.Data = null;
                response.StatusCode = (int)HttpStatusCode.OK;
                response.Message = "No File Available for Upload";
                response.Successful = false;
                return await Task.FromResult(response);
            }
            foreach (var attachment in model.MyFile)
            {
                if (ConstantHelper.CheckIfPdfFile(attachment))
                {
                    MandateApprovalAttachment mandateAttachment = new MandateApprovalAttachment();
                    string uploadFolder = Path.Combine(_iWebHostEnvironment.WebRootPath, "files/my_attachments");
                    fileName = Guid.NewGuid().ToString()   DateTime.Now.ToString("yyyyMMddHHmmss")   "_"   attachment.FileName;
                    string filePath = Path.Combine(uploadFolder, fileName);
                    //attachment.CopyTo(fileStream);
                    using (var fileStream = new FileStream(filePath, FileMode.Create))
                    {
                        await attachment.CopyToAsync(fileStream);
                    }
                    mandateAttachment.FileType = Path.GetExtension(attachment.FileName);
                    mandateAttachment.MimeType = attachment.ContentType;
                    mandateAttachment.FileName = fileName;
                    mandateAttachment.FilePath = filePath; 
                    await _unitOfWork.AdminMandateAttachments.InsertAsync(mandateAttachment);
                    await _unitOfWork.Save();
                }
                else
                {
                    response.Data = null;
                    response.StatusCode = (int)HttpStatusCode.OK;
                    response.Message = "Invalid File Extension! Kindly attach PDF File";
                    response.Successful = false;
                    return response;
                }
            }

            response.Message = "Successfully";
            transaction.Complete();
            response.StatusCode = (int)HttpStatusCode.OK;
            response.Successful = true;
            return response;
    catch (Exception ex)
    {
        response.Message = "An error occured";
        response.Successful = false;
        response.StatusCode = (int)HttpStatusCode.BadRequest;
        return response;
    }
}

I have validated that the FileType should be only PDF, and this is working.

But now, how do I validate that the Maximum FileSize should not excel exceed 5MB, and also save the FileSize into the DB?

Thanks

CodePudding user response：

There is an IFormFile.Length property, that will return the length of that file in bytes. (https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.http.iformfile.length?view=aspnetcore-6.0)

So given, that attachment is an IFormFile, you can validate this by checking

attachment.Length <= 5 * 1024 * 1024