I’m facing a problem downloading the file in Asp.Net core or maybe I’m not writing the right code.
I have an Asp.Net Core Web API with some methods to GetAllFiles, Upload, and Download files.

I’ve one method in my API’s controller to download the file(Code added below)

[HttpGet("{id}")]
public async Task<IActionResult> DownloadFile(Guid id)
{
    var fileInDb = pdfRepository.GetByIdAsync(x=>x.Pdf_Pk == id, false);

    if(fileInDb == null)
    {
        return NotFound();
    }

    //var fileName = _data.PdfDetail.Where(x => x.Pdf_Pk == id).Select(x => x.FileName).FirstOrDefault();
    var filePath = Path.Combine(Directory.GetCurrentDirectory(), "root\Files", fileInDb.Result.FileName);
    var provider = new FileExtensionContentTypeProvider();

    if(!provider.TryGetContentType(filePath, out var contentType))
    {
        contentType = "application/octet-stream";
    }

    var bytes = await System.IO.File.ReadAllBytesAsync(filePath);
    return File(bytes, contentType, Path.GetFileName(filePath));            
}

Here I’m returning the File.

I’m calling this method from my Web APP’s Controller.
Code for Download Method

public async Task<IActionResult> Download(Guid Id)
{
   return RedirectToAction("Index" ,await PdfServices.DownloadAsync<ApiResponse>(Id));
   
}

Here PdfServices.DownloadAsync is the service method, the code written below

public Task<T> DownloadAsync<T>(Guid Id)
{
    return SendAsync<T>(new ApiRequest()
    {
        type = APIRequestHeader.APIRequest.ApiType.Get,
        Data = Id,
        Url = ApiUrl + "/api/PdfManager/"+Id
    });
}

Now I’m calling this SendAsync Method which is used to send requests to API Methods and find the content, and I’m performing, serializing/deserializing here

public async Task<T> SendAsync<T>(ApiRequest request)
{
    try
    {
        var client = httpClientFactory.CreateClient("PdfManager");
        HttpRequestMessage message = new();
        message.Headers.Add("Accept", "Applicaiton/Json");
        message.RequestUri = new Uri(request.Url);

        if(request.Data != null)
        {
            message.Content = new StringContent(JsonConvert.SerializeObject(request.Data), Encoding.UTF8, "Application/Json");
        }
        switch(request.type)
        {
            case APIRequest.ApiType.Post:
                message.Method = HttpMethod.Post;
                break;
            case APIRequest.ApiType.Put:
                message.Method = HttpMethod.Put;
                break;
            case APIRequest.ApiType.Delete:
                message.Method = HttpMethod.Delete;
                break;
            default:
                message.Method = HttpMethod.Get;
                break;
        }

        HttpResponseMessage hrm = null;
        hrm = await client.SendAsync(message);
        var apiContent = await hrm.Content.ReadAsStringAsync();
        if(true) //Don't know what to write in this, to download this file
        {
            var readByte = hrm.Content.ReadAsByteArrayAsync();                    

            using(MemoryStream ms =new MemoryStream(readByte.Result))
            {
                var writer = new BinaryWriter(ms, Encoding.UTF8, false);

                var res = new FileContentResult(readByte.Result, hrm.Content.Headers.ContentType.MediaType);
                //return (T)res;
                var test = JsonConvert.DeserializeObject<T>(res);
            }
        }
        
        var apiResponse = JsonConvert.DeserializeObject<T>(apiContent);
        return apiResponse;

    }
    catch(Exception ex)
    {
        var dto = new ApiResponse
        {
            ErrorMessage = new List<string> { Convert.ToString(ex.ToString())},
            IsSuccess = false
        };
        var res = JsonConvert.SerializeObject(dto);
        var ApiResponse = JsonConvert.DeserializeObject<T>(res);
        return ApiResponse;
    }
}

Now, Method will be used for all operations like GettingAllFiles, UploadingFiles, DeleatingFiles and Also DownloadFile.
Because we are returning the file from API’s Controller, Now how can I download that file

I’m not able to read Content as string

 hrm.Content.ReadAsStringAsync();

because our content is not a string, it contains the files

If I read it as ByteArray then I’m not able to deserialize the object because it’ll ask for a type

How can I download this file coming into the Content from API’s controller?
how should I read it, what to return?