How to Get byte array properly from an Web Api Method in C#?

Question

I have the following controller method:

[HttpPost]
[Route("SomeRoute")]
public byte[] MyMethod([FromBody] string ID)
{
  byte[] mybytearray = db.get         


        

Answer 1

From WEBAPI/Server end, pass the values like :

String base64 = Convert.ToBase64String(bytes);     //Convert to ToBase64String

and receive the values from client

response = client.GetAsync("URL/home/GetFIle?id=" + File_id).Result;

responseBody = await response.Content.ReadAsStringAsync();

mybytearray = Convert.FromBase64String(responseBody);    //Convert to FromBase64String

Answer 2

Instead of this

mybytearray = response.Content.ReadAsByteArrayAsync().Result;//Here is the problem

Use this

string result=null;
result = response.Content.ReadAsStringAsync().Result.Replace("\"", string.Empty);
 mybytearray=Convert.FromBase64String(result);

response was returning the byte array as base64encoded.

Answer 3

response.Content.ReadAsAsync<byte[]>().Result //Put this code in your client.

I want to make it clear that ReadAsAsync<byte[]>() and ReadAsByteArrayAsync() do NOT act the same.

ReadAsByteArrayAsync() turns everything into a Base64 Byte Array. It doesn't get the non-Base64 byte[] from response.Content but ReadAsAsync<byte[]>() does

Answer 4

HTTP is a text based protocol. edit: HTTP can transport raw bytes as well. Luaan's answer is better.

The returned byte array will be converted into text in some way, depending on how the MediaTypeFormatterCollection is set up on the server and on the format requested by the HTTP client with the Accept header. The bytes will typically be converted to text by base64-encoding. The response may also be packaged further into JSON or XML, but the ratio of the expected length (528) to the actual length (706) seems to indicate a simple base64 string.

On the client side, you are not looking at the original bytes but at the bytes of this text representation. I would try reading the data as a string with ReadAsStringAsync and inspect it to see what format it is in. Also look at the headers of the response.

You should then parse this text accordingly to get the original bytes, e.g. with Convert.FromBase64String.

Answer 5

Actually, HTTP can handle "raw" binary as well - the protocol itself is text based, but the payload can be binary (see all those files you download from the internet using HTTP).

There is a way to do this in WebApi - you just have to use StreamContent or ByteArrayContent as the content, so it does involve some manual work:

public HttpResponseMessage ReturnBytes(byte[] bytes)
{
  HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
  result.Content = new ByteArrayContent(bytes);
  result.Content.Headers.ContentType = 
      new MediaTypeHeaderValue("application/octet-stream");

  return result;
}

It may be possible to do the same thing using some attribute or something, but I don't know how.

Answer 6

Change your controller with this and you'll get the same size that you send

[HttpPost]
[Route("SomeRoute")]
public FileStreamResult MyMethod([FromBody] string ID)
{
  byte[] mybytearray = db.getmybytearray(ID);
  return File(new MemoryStream(mybytearray), "application/octet-stream");
}

This is an issue https://github.com/aspnet/Mvc/issues/7926