ASP.NET Web API Streaming a file - c#

I am using Web API to serve the requests for files. File may be on disk or on some other server. The API controller sends a forward request or reads the file from the system and returns it.
public HttpResponseMessage GetResponse(string uri, HttpRequestMessage request)
{
HttpResponseMessage response = new HttpResponseMessage();
try
{
string newUrl = MapUrl(uri);
Stream responseStream = CreateResponse(request, newUrl);
response.Content = new StreamContent(responseStream);
return response;
}
catch (Exception ex)
{
response.StatusCode = HttpStatusCode.NotFound;
response.Content = new StringContent(ex.ToString());
return response;
}
}
CreateResponse() either returns a FileStream or GetResponseStream() based on the current configuration.
No Content-Length header is being added as the file is being streamed, in the response headers I see Transfer-Encoding: chunked header as expected.
But in case the file has to be served by reading from the filesystem IIS automatically adds the Content-Length header - which should not have happened as the file is being read as a stream by the code,
return new FileStream(newUrl, FileMode.Open);
any custom headers added show up confirming response was sent by the code and not IIS directly.
In global.asax routes.RouteExistingFiles = true;

Related

Upload file to SharePoint using HTTP Client is not working

I want to upload a static file to SharePoint using Graph API and HTTP Client.
We have a folder where the file is kept, now we have to read the file from the folder and upload it to SharePoint.
Stream stream = GetFile() //this will return file data as a Stream.
HttpClient httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.Authorization
= new AuthenticationHeaderValue("Bearer", token);
MultipartFormDataContent form = new MultipartFormDataContent();
var streamContent = new StreamContent(stream);
var imageContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");
form.Add(imageContent, "Test.pdf");
var response = httpClient.PostAsync(#"https://graph.microsoft.com/v1.0/sites/{siteId}/lists/{folderName}/drive/root:/childFolder/Test.pdf:/createUploadSession", form).Result;
We are getting BadRequest response for the above request.
According to the documentation no request body is required for createUploadSession endpoint but if you specify the body it must be json like this
Content-Type: application/json
{
"item": {
"#odata.type": "microsoft.graph.driveItemUploadableProperties",
"#microsoft.graph.conflictBehavior": "rename",
"name": "largefile.dat"
}
}
The response will contain uploadSession resource type.
To upload the file, or a portion of the file, you need to make a PUT request to the uploadUrl value received in the createUploadSession response. You can upload the entire file, or split the file into multiple byte ranges, as long as the maximum bytes in any given request is less than 60 MiB.
Resources:
driveItemUploadableProperties
uploadSession
Upload bytes to the upload session

Send a 'Stream' over a PutAsync request

I'm trying my hand at .NET Core but I'm stuck trying to convert multipart/form-data to an application/octet-stream to send via a PUT request. Anybody have any expertise I could borrow?
[HttpPost("fooBar"), ActionName("FooBar")]
public async Task<IActionResult> PostFooBar() {
HttpResponseMessage putResponse = await _httpClient.PutAsync(url, HttpContext.Request.Body);
}
Update: I think I might have two issues here:
My input format is multipart/form-data so I need to split out the file from the form data.
My output format must be application-octet stream but PutAsync expects HttpContent.
I had been trying to do something similar and having issues. I needed to PUT large files (>1.5GB) to a bucket on Amazon S3 using a pre-signed URL. The implementation on Amazon for .NET would fail for large files.
Here was my solution:
static HttpClient client = new HttpClient();
client.Timeout = TimeSpan.FromMinutes(60);
static async Task<bool> UploadLargeObjectAsync(string presignedUrl, string file)
{
Console.WriteLine("Uploading " + file + " to bucket...");
try
{
StreamContent strm = new StreamContent(new FileStream(file, FileMode.Open, FileAccess.Read));
strm.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
HttpResponseMessage putRespMsg = await client.PutAsync(presignedUrl, strm);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
return false;
}
return true;
}
Turns out Request has a Form property that contains a Files property that has an OpenReadStream() function on it to convert it into a stream. How exactly I was supposed to know that, I'm not sure.
Either way, here's the solution:
StreamContent stream = new StreamContent(HttpContext.Request.Form.Files[0].OpenReadStream());
HttpResponseMessage putResponse = await _httpClient.PutAsync(url, stream);

How to Post a web request and receive a file from web API response?

I have an Infopath Form Template on Sharepoint, I want to add a button there so when the user clicks on it, it will POST an string to the following Web API. The following web API is tested and returns an excel file as shown:
I want to Post the FileName of the excel file using post request and it is important for me the request method to be POST type. and then the user will download a file with the specified 'FileName'.
Actually i want to use post method because at the next stage i will send the content of the excel file too.
Important Note: I only can use .Net FrameWork 3.5 because this is the only framework supported in InfoPath Form Templates.
[HttpPost]
public HttpResponseMessage Post([FromBody]string FileName)
{
string reqBook = "c:\somefile.xlsx";
//converting Excel(xlsx) file into bytes array
var dataBytes = File.ReadAllBytes(reqBook);
//adding bytes to memory stream
var dataStream = new MemoryStream(dataBytes);
HttpResponseMessage httpResponseMessage = Request.CreateResponse(HttpStatusCode.OK);
httpResponseMessage.Content = new StreamContent(dataStream);
httpResponseMessage.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
httpResponseMessage.Content.Headers.ContentDisposition.FileName = FileName;
httpResponseMessage.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
return httpResponseMessage;
}
When you perform the HttpPost on the client side, you will want to read the HttpResponseStream to get the byte data of the response stream.
Once you have the response stream data, you can then deserialize it to the type of object in C# you want, or you could alternatively just write it to the disk as
File.WriteAllBytes("someexcel.xlsx",data);
An easy way to do it would be with the HttpClient class.
HttpClient client = new HttpClient();
var response = client.PostAsync("", null).Result;
var content = response.Content.ReadAsByteArrayAsync().Result;
File.WriteAllBytes("excel.xlsx", content);
Just fill in the PostAsync bit with the Url and the content you wish to post.
I am using .Result to keep everything synchronous - but you can use 'await' if you prefer.
If you are working with HttpWebRequests - then the process becomes more complicated, as you need to manage the streams yourself.
The HttpClient will manage and handle it all for you - so I recommend it, unless there is something special it needs to do that it currently does not.
Due to your .Net 3.5 requirement:
private static HttpWebResponse MakeRequest(string url, string postArgument)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
request.ContentType = "multipart/form-data;";
Stream stream = request.GetRequestStream();
string result = string.Format("arg1={0}", postArgument);
byte[] value = Encoding.UTF8.GetBytes(result);
stream.Write(value, 0, value.Length);
stream.Close();
return (HttpWebResponse)request.GetResponse();
}
You can then do:
var response = MakeRequest("http://mywebsite.com/ProcessExcel", "accounts.xlsx");
And then do
Stream objStream = response .GetResponseStream();
BinaryReader breader = new BinaryReader(objStream);
byte[] data= breader.ReadBytes((int)webresponse.ContentLength);
File.WriteAllBytes("excel.xlsx",data);

Upload file on Dropbox using REST api

Below code uploads files on a server with same name, size and file type (like it's uploading a dummy file). But when do I try to view it, it shows noting. When I try to upload a .txt file it works. What's wrong?
public static void UploadFile(string accessToken,string path,HttpPostedFileBase file)
{
try
{
var client = new RestClient("https://content.dropboxapi.com/1/files_put/auto/Abc/" + file.FileName);
var request = new RestRequest(Method.PUT);
request.AddHeader("Authorization", "Bearer " + accessToken);
request.AddHeader("Content-Type", file.ContentType);
//request.AddHeader("Content-Length", file.ContentLength.ToString());
request.AddFile("file", path);
IRestResponse response = client.Execute(request);
}
catch (Exception ex)
{
throw ex;
}
}
I assume from the classes I see that you're using RestSharp? I'm not all that familiar, but from a quick search, it doesn't look like AddFile does what you want. (That sets up a multipart form upload, which is not what the Dropbox API expects.)
Instead of request.AddFile(...), I think you want something like this (completely untested):
// Get a byte array of the file content. Note that this involves reading
// the entire file into memory! I couldn't immediately find a way to work
// with the stream itself in RestSharp.
MemoryStream target = new MemoryStream();
file.InputStream.CopyTo(target);
byte[] data = target.ToArray();
// Send those bytes as the body of your HTTP request.
request.AddParameter("application/octet-stream", data, ParameterType.RequestBody);

How to get the file size from http headers

I want to get the size of an http:/.../file before I download it. The file can be a webpage, image, or a media file. Can this be done with HTTP headers? How do I download just the file HTTP header?
Yes, assuming the HTTP server you're talking to supports/allows this:
public long GetFileSize(string url)
{
long result = -1;
System.Net.WebRequest req = System.Net.WebRequest.Create(url);
req.Method = "HEAD";
using (System.Net.WebResponse resp = req.GetResponse())
{
if (long.TryParse(resp.Headers.Get("Content-Length"), out long ContentLength))
{
result = ContentLength;
}
}
return result;
}
If using the HEAD method is not allowed, or the Content-Length header is not present in the server reply, the only way to determine the size of the content on the server is to download it. Since this is not particularly reliable, most servers will include this information.
Can this be done with HTTP headers?
Yes, this is the way to go. If the information is provided, it's in the header as the Content-Length. Note, however, that this is not necessarily the case.
Downloading only the header can be done using a HEAD request instead of GET. Maybe the following code helps:
HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://example.com/");
req.Method = "HEAD";
long len;
using(HttpWebResponse resp = (HttpWebResponse)(req.GetResponse()))
{
len = resp.ContentLength;
}
Notice the property for the content length on the HttpWebResponse object – no need to parse the Content-Length header manually.
Note that not every server accepts HTTP HEAD requests. One alternative approach to get the file size is to make an HTTP GET call to the server requesting only a portion of the file to keep the response small and retrieve the file size from the metadata that is returned as part of the response content header.
The standard System.Net.Http.HttpClient can be used to accomplish this. The partial content is requested by setting a byte range on the request message header as:
request.Headers.Range = new RangeHeaderValue(startByte, endByte)
The server responds with a message containing the requested range as well as the entire file size. This information is returned in the response content header (response.Content.Header) with the key "Content-Range".
Here's an example of the content range in the response message content header:
{
"Key": "Content-Range",
"Value": [
"bytes 0-15/2328372"
]
}
In this example the header value implies the response contains bytes 0 to 15 (i.e., 16 bytes total) and the file is 2,328,372 bytes in its entirety.
Here's a sample implementation of this method:
public static class HttpClientExtensions
{
public static async Task<long> GetContentSizeAsync(this System.Net.Http.HttpClient client, string url)
{
using (var request = new System.Net.Http.HttpRequestMessage(System.Net.Http.HttpMethod.Get, url))
{
// In order to keep the response as small as possible, set the requested byte range to [0,0] (i.e., only the first byte)
request.Headers.Range = new System.Net.Http.Headers.RangeHeaderValue(from: 0, to: 0);
using (var response = await client.SendAsync(request))
{
response.EnsureSuccessStatusCode();
if (response.StatusCode != System.Net.HttpStatusCode.PartialContent)
throw new System.Net.WebException($"expected partial content response ({System.Net.HttpStatusCode.PartialContent}), instead received: {response.StatusCode}");
var contentRange = response.Content.Headers.GetValues(#"Content-Range").Single();
var lengthString = System.Text.RegularExpressions.Regex.Match(contentRange, #"(?<=^bytes\s[0-9]+\-[0-9]+/)[0-9]+$").Value;
return long.Parse(lengthString);
}
}
}
}
WebClient webClient = new WebClient();
webClient.OpenRead("http://stackoverflow.com/robots.txt");
long totalSizeBytes= Convert.ToInt64(webClient.ResponseHeaders["Content-Length"]);
Console.WriteLine((totalSizeBytes));
HttpClient client = new HttpClient(
new HttpClientHandler() {
Proxy = null, UseProxy = false
} // removes the delay getting a response from the server, if you not use Proxy
);
public async Task<long?> GetContentSizeAsync(string url) {
using (HttpResponseMessage responce = await client.GetAsync(url))
return responce.Content.Headers.ContentLength;
}

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