Unable to cast object of type 'System.Web.HttpInputStream' to type 'System.IO.FileStream' MVC 3

Question

I have met an issue regarding the casting type from HttpInputStream to FileStream.

How I did ?

I have a HttpPostedFileBase object and I want to have FileStream.

I wrote:

public void Test(HttpPostedFileBase postedFile) {
  FileStream fileStream = (FileStream)(postedFile.InputStream); // throw exception

  FileStream anotherFileStream = postedFile.InputStream as FileStream; // null
}

I tried also

public void Test(HttpPostedFileBase postedFile) {
  Stream stream = postedFile.InputStream as Stream;

  FileStream myFile = (FileStream)stream;

}

But no success.

Why at postedFile.InputStream comes HttpInputStream type ?

And how could I solve this issue ?

Thanks

Your file base InputStream (incomming stream) is HttpInputStream, not FileStream. You have to read from it and save it somewhere, maybe to your local file. For this you can use FileStream. — OzrenTkalcecKrznaric, Oct 29 '12 at 10:39

score 18 · Answer 1 · answered May 24 '13 at 16:05

18

public byte[] LoadUploadedFile(HttpPostedFileBase uploadedFile)
{
    var buf = new byte[uploadedFile.InputStream.Length];
    uploadedFile.InputStream.Read(buf, 0, (int)uploadedFile.InputStream.Length);
    return buf;
}

answered May 24 '13 at 16:05

yarg

679
6
11

score 11 · Accepted Answer · answered Oct 29 '12 at 10:37

11

The stream that you get from your HTTP call is read-only sequential (non-seekable) and the FileStream is read/write seekable. You will need first to read the entire stream from the HTTP call into a byte array, then create the FileStream from that array.

answered Oct 29 '12 at 10:37

Kevin

552
2
4

16

An example can you provide ? – Snake Eyes Oct 29 '12 at 10:46
An accepted answer with no code example... Ugh – Taylor Brown Aug 15 '22 at 23:51

score 11 · Answer 3 · answered Feb 20 '14 at 03:44

I used the following and it worked just fine for the same situation

MemoryStream streamIWant = new MemoryStream();
using (Stream mystream = (Stream)AmazonS3Service.GetObjectStream(AWSAlbumBucketName, ObjectId))                                                            
{
    mystream.CopyTo(streamIWant);
}
return streamIWant;

The GetObjectStream returns the same type of string mentioned in the question.

codingbiz · Answer 4 · 2012-10-29T10:52:28.667

1

You can use the .SaveAs method to save the file content. HttpInputSteam probably because it's uploaded through http [browser]

 postedFile.SaveAs("Full Path to file name");

You can also use CopyTo

FileStream f = new FileStream(fullPath, FileMode.CreateNew);
postedFile.InputStream.CopyTo(f);
f.Close();

edited Oct 29 '12 at 10:52

answered Oct 29 '12 at 10:36

codingbiz

26,179
8
59
96

score 0 · Answer 5 · answered Jun 21 '17 at 12:35

Below code worked for me..

Use a BinaryReader object to return a byte array from the stream like:

byte[] fileData = null;
using (var binaryReader = new BinaryReader(Request.Files[0].InputStream))
{
    fileData = binaryReader.ReadBytes(Request.Files[0].ContentLength);
}

How to create byte array from HttpPostedFile

score 0 · Answer 6 · answered Sep 03 '21 at 07:56

It will work for you. IFormFile file;

        if (file != null)
        {
            byte[]? image = Array.Empty<byte>();
            await using var memoryStream = new MemoryStream();
            await file!.CopyToAsync(memoryStream);
            image = memoryStream.ToArray();
        }

score 0 · Answer 7 · answered Jul 06 '22 at 04:41

First convert to byte array then convert to Stream.

[HttpPost]
[Route("api/TestReader/UploadTestReaderStudentsGrade")]
public IHttpActionResult UploadTestReaderStudentsGrade()
{
    HttpPostedFile httpPostedFile = HttpContext.Current.Request.Files[0];
    var fileBytes = new byte[httpPostedFile.InputStream.Length];
    httpPostedFile.InputStream.Read(fileBytes, 0, (int)httpPostedFile.InputStream.Length); // to byte array
    Stream stream = new MemoryStream(fileBytes); // to Stream

    Workbook workbook = new Workbook(stream);
    return Ok();
}

Unable to cast object of type 'System.Web.HttpInputStream' to type 'System.IO.FileStream' MVC 3

7 Answers7

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