I'm struggling with a easy problem. I want to download an image from web using this code:
WebRequest requestPic = WebRequest.Create(#"http://something.com/" + id + ".jpg");
WebResponse responsePic = await requestPic.GetResponseAsync();
Now I wanted to write the WebResponse's stream in a StorageFile (eg. create a file id.jpg in the app's storage), but I haven't found any way to achieve that. I searched the web for it, but no success - all ways incompatible Stream types and so on.
Could you please help?
I have found the following solution, which works and is not too complicated.
public async static Task<StorageFile> SaveAsync(
Uri fileUri,
StorageFolder folder,
string fileName)
{
var file = await folder.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);
var downloader = new BackgroundDownloader();
var download = downloader.CreateDownload(
fileUri,
file);
var res = await download.StartAsync();
return file;
}
You will need to read the response stream into a buffer then write the data to a StorageFile. THe following code shows an example:
var fStream = responsePic.GetResponseStream();
var file = await ApplicationData.Current.LocalFolder.CreateFileAsync("testfile.txt");
using (var ostream = await file.OpenStreamForWriteAsync())
{
int count = 0;
do
{
var buffer = new byte[1024];
count = fStream.Read(buffer, 0, 1024);
await ostream.WriteAsync(buffer, 0, count);
}
while (fStream.CanRead && count > 0);
}
That can be done using the C++ REST SDK in Windows Store Apps. It's explained by HTTP Client Tutorial.
Related
I am using Microsoft Graph SDK to upload file in chunks in OneDrive. I am using below code to upload the file:
try
{
GraphServiceClient graphClient = this.GetGraphServiceClient(accessToken);
string fileName = Path.GetFileName(srcFilePath);
using (var fileContentStream = System.IO.File.Open(srcFilePath, System.IO.FileMode.Open))
{
var uploadSession = await graphClient.Me.Drive.Root.ItemWithPath(fileName).CreateUploadSession().Request().PostAsync();
var maxChunkSize = 5 * 1024 * 1024;
var provider = new ChunkedUploadProvider(uploadSession, graphClient, fileContentStream, maxChunkSize);
var chunkRequests = provider.GetUploadChunkRequests();
var readBuffer = new byte[maxChunkSize];
var trackedExceptions = new List<Exception>();
Microsoft.Graph.DriveItem itemResult = null;
foreach (var request in chunkRequests)
{
var result = await provider.GetChunkRequestResponseAsync(request, readBuffer, trackedExceptions);
if (result.UploadSucceeded)
{
itemResult = result.ItemResponse;
}
}
}
}
catch (Microsoft.Graph.ServiceException e)
{
}
catch (Exception ex)
{
}
The above code works fine with normal file names. However, when I am trying to upload a file with name as Test#123.pdf, "Object reference not set to an object" exception is thrown at line var provider = new ChunkedUploadProvider(uploadSession, graphClient, fileContentStream, maxChunkSize); Please see below screenshot:
Is this a limitation of OneDrive SDK, or am I not passing the parameters correctly?
The # sign has a special meaning in a URL. Before you can use it, you'll need to URL Encode the file name: Test%23123.pdf.
I am new to Xamarin iOS, i need to download multiple videos at same time. how should i achieve this ? is there any class which can help me download similar to the DownloadManager in Android.
You can try this approaches
public void getData(List<String> urls) {
// define the HttpClient
var handler = new HttpClientHandler { AllowAutoRedirect=false };
var client = new HttpClient(handler);
// define file path
var path=Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
// start download
System.Threading.Tasks.Parallel.ForEach(urls, async (url) => {
var uri = new Uri(url);
var fileName = System.IO.Path.GetFileName(uri.LocalPath);
// download the file
var data = await client.GetByteArrayAsync(uri);
// save file on disk
System.IO.File.WriteAllBytes(System.IO.Path.Combine(path, fileName), data);
});
}
I'm just new in this PCL libraries, I'm developing an iPhone app with Xamarin and I can't find the way to save it on the phone. The closest I get is with PCLStorage but he only saves text.
There is another way that I can save binary files with other procedure.
Thank you.
foreach (images element in json_object)
{
//var nameFile = Path.Combine (directoryname, element.name);
try{
IFile file = await folder_new.GetFileAsync(element.name);
}catch(FileNotFoundException ex ){
RestClient _Client = new RestClient(element.root);
RestRequest request_file = new RestRequest("/images/{FileName}");
request_file.AddParameter("FileName", element.name, ParameterType.UrlSegment);
_Client.ExecuteAsync<MemoryStream>(
request_file,
async Response =>
{
if (Response != null)
{
IFolder rootFolder_new = FileSystem.Current.LocalStorage;
IFile file_new = await rootFolder_new.CreateFileAsync(element.name,CreationCollisionOption.ReplaceExisting);
await file_new.WriteAllTextAsync(Response.Data);
}
});
}
}
Use the IFile.OpenAsync method to get a stream which you can use to read/write binary data. Here's how you would read a file:
IFile file = await folder_new.GetFileAsync(element.name);
using (Stream stream = await file.OpenAsync(FileAccess.Read))
{
// Read stream and process binary data from it...
}
I'm trying to write a WebApi service that receives a file, does a trivial manipulation, and sends the file back. I'm having issues on sending and/or receiving the file from the service.
The issue I'm having is that the file returned from the service is ~1.5x larger than the manipulated file, e.g. when the file is returned it's like 300kb instead of the 200kb it should be.
I assume its being wrapped and or manipulated somehow, and I'm unsure of how to receive it properly. The code for the WebAPI service and the method that calls the web service are included below
In, the WebApi service, when I hit the line return Ok(bufferResult), the file is a byte[253312]
In the method that calls the web service, after the file is manipulated and returned, following the line var content = stream.Result;, the stream has a length of 337754 bytes.
Web API service code
public ConversionController: APIController{
public async Task<IHttpActionResult> TransformImage()
{
if (!Request.Content.IsMimeMultipartContent())
throw new Exception();
var provider = new MultipartMemoryStreamProvider();
await Request.Content.ReadAsMultipartAsync(provider);
var file = provider.Contents.First();
var filename = file.Headers.ContentDisposition.FileName.Trim('\"');
var buffer = await file.ReadAsByteArrayAsync();
var stream = new MemoryStream(buffer);
// [file manipulations omitted;]
// [the result is populated into a MemoryStream named response ]
//debug : save memory stream to disk to make sure tranformation is successfull
/*response.Position = 0;
path = #"C:\temp\file.ext";
using (var fileStream = System.IO.File.Create(path))
{
saveStream.CopyTo(fileStream);
}*/
var bufferResult = response.GetBuffer();
return Ok(bufferResult);
}
}
Method Calling the Service
public async Task<ActionResult> AsyncConvert()
{
var url = "http://localhost:49246/api/conversion/transformImage";
var filepath = "drive/file/path.ext";
HttpContent fileContent = new ByteArrayContent(System.IO.File.ReadAllBytes(filepath));
using (var client = new HttpClient())
{
using (var formData = new MultipartFormDataContent())
{
formData.Add(fileContent, "file", "fileName");
//call service
var response = client.PostAsync(url, formData).Result;
if (!response.IsSuccessStatusCode)
{
throw new Exception();
}
else
{
if (response.Content.GetType() != typeof(System.Net.Http.StreamContent))
throw new Exception();
var stream = response.Content.ReadAsStreamAsync();
var content = stream.Result;
var path = #"drive\completed\name.ext";
using (var fileStream = System.IO.File.Create(path))
{
content.CopyTo(fileStream);
}
}
}
}
return null;
}
I'm still new to streams and WebApi, so I may be missing something quite obvious. Why are the file streams different sizes? (eg. is it wrapped and how do I unwrap and/or receive the stream)
okay, to receive the file correctly, I needed to replace the line
var stream = response.Content.ReadAsStreamAsync();
with
var contents = await response.Content.ReadAsAsync<Byte[]>();
to provide the correct type for the binding
so, the later part of the methods that calls the service looks something like
var content = await response.Content.ReadAsAsync<Byte[]>();
var saveStream = new MemoryStream(content);
saveStream.Position = 0;
//Debug: save converted file to disk
/*
var path = #"drive\completed\name.ext";
using (var fileStream = System.IO.File.Create(path))
{
saveStream.CopyTo(fileStream);
}*/
I have created a web api which connects users to dropbox via OAuth. I am using an API to interact with Dropbox, which works locally as I would like, however when I deploy the API to my Azure server, I am unable to download. I had anticipated this would happen, as my API is currently hard codded to a path on my machine.
Here is the method I am using:
NOTE: I call this method through an ActionResult, as part of the MVC portion of my project
public FileSystemInfo DownloadFile(string root, string path)
{
var uri = new Uri(new Uri(DropboxRestApi.ApiContentServer),
String.Format("files?root={0}&path={1}",
root, UpperCaseUrlEncode(path)));
var oauth = new OAuth();
var requestUri = oauth.SignRequest(uri, _consumerKey, _consumerSecret, _accessToken);
var request = (HttpWebRequest) WebRequest.Create(requestUri);
request.Method = WebRequestMethods.Http.Get;
var response = request.GetResponse();
var metadata = response.Headers["x-dropbox-metadata"];
var file = ParseJson<FileSystemInfo>(metadata);
using (Stream responseStream = response.GetResponseStream())
using (MemoryStream memoryStream = new MemoryStream())
{
byte[] buffer = new byte[1024];
int bytesRead;
do
{
bytesRead = responseStream.Read(buffer, 0, buffer.Length);
memoryStream.Write(buffer, 0, bytesRead);
} while (bytesRead > 0);
file.Data = memoryStream.ToArray();
}
return file;
}
This is where I call the method in my action result.
var file = api.DownloadFile("dropbox", "Public/downloadThis.jpg");
path = file.Path;
file.Save(#"....\Desktop\DemoTest\Downloads\downloadThis.jpg"); --- this is the problem & *Save* is a stream writer
Is there a procedure to follow when downloading files from a server on a browser?
public ActionResult download(Models.downloadModel dowld, Models.LoggerView log)
{
string TC_ID = Request.QueryString["id"].ToString();
string filename = TC_ID+"_LoggerData" + ".zip";
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition", "attachment;filename=" + filename);
Response.TransmitFile(Server.MapPath("~/files/" + filename));
Response.End();
}