I am trying to download files from azure to computer via an web app. It works when I run locally the project, but when uploaded to ftp server it does not download.
I have tried Environment.SpecialFolder.Peronal, Desktop, etc.
public async Task<bool> DownloadBlobAsync(string file, string fileExtension, string directory)
{
string downlaodPath = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
_container = _client.GetContainerReference(containerName);
_directoy = _container.GetDirectoryReference(directory);
CloudBlockBlob blockBlob = _directoy.GetBlockBlobReference(file + "." + fileExtension);
using (var fileStream = File.OpenWrite(downlaodPath + "/"+ file + "." + fileExtension))
{
await blockBlob.DownloadToStreamAsync(fileStream);
return true;
}
}
The expected output should be on the documents or desktop.
The issue that you are seeing is due to the fact that your code is executing on the webserver, not on the clients (users) machine.
In other words, when you try to save to Environment.SpecialFolder.Personal, you're trying to save it to that folder on the web server, not the users desktop computer.
What you need to do is return the content of the blob in the request, and let the browser save the file - the user is likely to be prompted (depending on their browser settings) where exactly to save it. You should not be specifying this.
Here is an example of how to do this:
public async Task<HttpResponseMessage> DownloadBlobAsync(string file, string fileExtension, string directory)
{
_container = _client.GetContainerReference(containerName);
_directoy = _container.GetDirectoryReference(directory);
CloudBlockBlob blockBlob = _directoy.GetBlockBlobReference(file + "." + fileExtension);
using (var ms = new MemoryStream())
{
await blockBlob.DownloadToStreamAsync(ms);
var result = new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new ByteArrayContent(ms.ToArray())
};
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = "somefilename.ext"
};
result.Content.Headers.ContentType = new MediaTypeHeaderValue(blockBlob.Properties.ContentType);
return result;
}
}
Note that this is inefficient, as it will download the blob first to the webserver, and then return that to the client. It should be enough to get started.
When this endpoint is hit by the browser, the user will be prompted to save the file somewhere on their PC.
Related
Using DynamicPDF's Cloud API, instead of generating a pdf back to the local file system, I would like it to directly open in another browser tab to be available for printing immediately. How do I accomplish that?
The method I am using (.NET Core 6 / Blazor) is below:
public async Task CallDynPDFCloudAPI()
{
var basePath = #"JSONFiles\";
var apiKey = "foo";
var cloudPath = "bar.dlex";
Pdf pdf = new Pdf();
pdf.ApiKey = apiKey;
LayoutDataResource layoutDataResource = new LayoutDataResource(basePath + "FooBar.json");
pdf.AddDlex(cloudPath, layoutDataResource);
PdfResponse pdfResponse = pdf.Process();
if (pdfResponse.IsSuccessful)
{
File.WriteAllBytes(basePath + "Manifest_" + manifestBranch + ".pdf", pdfResponse.Content);
}
else
{
Console.WriteLine(pdfResponse.ErrorJson);
}
}
Reread article on https://learn.microsoft.com/en-us/aspnet/core/blazor/file-downloads?view=aspnetcore-6.0
#page "/file-download-1"
#using System.IO
#inject IJSRuntime JS
<h1> File Download Example</h1>
<button #onclick = "DownloadFileFromStream" >
Download File From Stream
</button>
#code {
private Stream CallDynPDFCloudAPI()
{
var basePath = #"JSONFiles\";
var apiKey = "foo";
var cloudPath = "bar.dlex";
Pdf pdf = new Pdf();
pdf.ApiKey = apiKey;
LayoutDataResource layoutDataResource = new LayoutDataResource(basePath + "FooBar.json");
pdf.AddDlex(cloudPath, layoutDataResource);
PdfResponse pdfResponse = pdf.Process();
if (pdfResponse.IsSuccessful)
{
return new MemoryStream(pdfResponse.Content);
}
else
{
throw new Exception("");
}
}
private async Task DownloadFileFromStream()
{
var fileStream = CallDynPDFCloudAPI();
var fileName = "file.pdf";
using var streamRef = new DotNetStreamReference(stream: fileStream);
await JS.InvokeVoidAsync("downloadFileFromStream", fileName, streamRef);
}
}
You won't be able to access the PDF content for this request from another browser tab. I'd recommend opening the new tab before making the call and then streaming it there. If you're using an 'a href' link, you can accomplish this by setting the 'target="_blank"' property of the 'a href'. If this is a form submission, you can set the 'target="_blank"' property of the 'form'.
The other option would be to store the PDF somewhere temporarily (as a file, in a DB or in BLOB storage) then stream it to the other tab once it's opened.
Ive impletented #Mihal's answer, with modified code suggested by #DynamicPDF to achieve the result I was looking for. My two goals were:
Not clutter the client device with excessive dowloaded files
Not needing to save the file in Server or DB
Javascript:
<script>
window.downloadFileFromStream = async (fileName,
contentStreamReference) => {
const arrayBuffer = await contentStreamReference.arrayBuffer();
const blob = new Blob([arrayBuffer], { type: 'application/pdf' });
const url = URL.createObjectURL(blob);
//--Opens PDF file in new Tab
fetch(url)
.then(response => response.blob())
.then(data => window.open(URL.createObjectURL(data), '_blank'))
//--Downloads file to Browser (uncomment if desired)
//const anchorElement = document.createElement('a');
//anchorElement.href = url;
//anchorElement.download = fileName ?? 'Manifest';
//anchorElement.click();
//anchorElement.remove();
//URL.revokeObjectURL(url);
}
</script>
*NOTE! My application is purely internal-facing to our organization. Our Windows client machines and browsers are managed by Group Policy. I have not yet tested this on Mac / Safari clients yet.
I have a controller in my dotnet core web application to fetch a resource from a Azure storage account in Azure and offer it to the user for download. The user can't directly access the Azure storage account, so my webapp works as a proxy and authenticates the user before service the file.
My doubt is if my implementation if efficient with large files? My concern is that DownloadToStreamAsync() actually fetches the entire file in the memory of the webapp before serving it.
public async Task<IActionResult> Serve(string path)
{
MemoryStream streamIn = null;
CloudFile file = null;
Stream fileStream = null;
var filename = Path.GetFileName(path);
// application-level permission checks checks
// fetching file from Azure Storage
try {
var storageConnectionString = _azureOptions.AzureStorageAccountConnectionString;
var storageAccount = CloudStorageAccount.Parse(storageConnectionString);
var fileClient = storageAccount.CreateCloudFileClient();
var share = fileClient.GetShareReference(_azureOptions.AzureStorageAccountContentShareName);
var root = share.GetRootDirectoryReference();
file = root.GetFileReference(path);
if (!await file.ExistsAsync())
{
return NotFound();
}
streamIn = new MemoryStream();
await file.DownloadToStreamAsync(streamIn);
fileStream = await file.OpenReadAsync();
} catch (StorageException e) {
_logger.LogError($"Error while retrieving content resource: {path}", e);
return NotFound();
}
return File(fileStream, _getContentType(filename));
}
You are right to have this concern because your code is downloading the entire blob to memory before uploading it to the client. This is very inefficient.
Furthermore, you are not even using the MemoryStream where you download the file. Just delete this code:
streamIn = new MemoryStream();
await file.DownloadToStreamAsync(streamIn);
The rest of the code should stream the file from Azure and stream it to the client in parallel.
I have written a small method that uploads files on Dropbox and that method is working absolutely fine but the issue is how can I get the URL of the uploaded image so that I hit that URL on browser and it shows me the image.
Here is the code of uploading files:
public static async Task Run()
{
var accessToken = ConfigurationManager.AppSettings["DropBoxAccessToken"];
using (var dbx = new DropboxClient(accessToken))
{
//var full = await dbx.Users.GetCurrentAccountAsync();
await Upload(dbx, "/Test", "Test Image.jpg");
}
}
static async Task Upload(DropboxClient dbx, string folder, string file)
{
var readContent = System.IO.File.ReadAllBytes(#"D:\Images\IMG_20161127_204200968.jpg");
using (var mem = new MemoryStream(readContent))
{
var updated = await dbx.Files.UploadAsync(
folder + "/" + file,
WriteMode.Overwrite.Instance,
body: mem);
var mediaInfo = updated.MediaInfo;
}
}
I have tried to get details of uploaded image by hovering on var updated but didn't get the URL.
Any help?
To get a link to a file via the Dropbox API, you have two options:
GetTemporaryLinkAsync: this returns a temporary link, but isn't meant for being displayed in the browser directly.
CreateSharedLinkWithSettingsAsync: this returns a shared link that points to a preview page for the file that can be displayed in the browser.
Our system has been used to upload millions of files over several years. The clients use the following code to send an authentication token and zip file to our WEB API on Windows Server 2008 R2. On our Windows 7 devices, the system works great. As we are attempting to move to Windows 10 devices, we have suddenly encountered an issue where the received file has blocks of data in a different order than the source file. The problem only occurs about half of the time, which makes it very difficult to track down.
client code (.NET 4.5)
private static void UploadFile(string srcFile, string username, string password)
{
if (File.Exists(srcFile))
{
ConnectionUtilities connUtil = new ConnectionUtilities();
string authToken = connUtil.GetAuthToken(username, password);
using (HttpContent authContent = new StringContent(authToken))
{
using (HttpContent fileStreamContent = new ByteArrayContent(File.ReadAllBytes(srcFile)))
{
FileInfo fi = new FileInfo(srcFile);
using (HttpClient client = new HttpClient())
using (MultipartFormDataContent formData = new MultipartFormDataContent())
{
client.DefaultRequestHeaders.ExpectContinue = false;
formData.Add(authContent, "auth");
formData.Add(fileStreamContent, "data", fi.Name);
var response = client.PostAsync(ConfigItems.hostName + "UploadData", formData).Result;
if (response.IsSuccessStatusCode)
{
File.Delete(srcFile);
}
}
}
}
}
}
WEB API code (.NET 4.5.2)
public async Task<HttpResponseMessage> PostUploadData()
{
if (Request.Content.IsMimeMultipartContent())
{
MultipartFormDataStreamProvider streamProvider =
MultipartFormDataStreamProvider(HttpContext.Current.Server.MapPath("~/app_data"));
await Request.Content.ReadAsMultipartAsync(streamProvider);
string auth = streamProvider.FormData["auth"];
if (auth != null)
{
auth = HttpUtility.UrlDecode(auth);
}
if (Util.IsValidUsernameAndPassword(auth))
{
string username = Util.GetUsername(auth);
foreach (var file in streamProvider.FileData)
{
DirectoryInfo di = new DirectoryInfo(ConfigurationManager.AppSettings["DataRoot"]);
di = di.CreateSubdirectory(username);
string contentFileName = file.Headers.ContentDisposition.FileName;
di = di.CreateSubdirectory("storage");
FileInfo fi = new FileInfo(file.LocalFileName);
string destFileName = Path.Combine(di.FullName, contentFileName);
File.Move(fi.FullName, destFileName);
}
return new HttpResponseMessage(HttpStatusCode.OK);
}
}
return new HttpResponseMessage(HttpStatusCode.ServiceUnavailable);
}
The problem initially manifests as a zipped file that can't open in Windows. Only by doing a hexadecimal compare did we determine that the file was all there, just not in the same order as the original.
Any thoughts on what might be causing the blocks of data to be reordered?
P.S. I know the HttpClient is not being used as effectively as possible.
After some long and tedious testing (Yay, scientific method) we determined that our web content filter software was causing the issue.
I'm working in a function to download pdfs from DropBox, I'm using ASP.net Core , everything works good. The only thing is that when you click in the download link it doesn't show any message and downloads the file. I would like to show the download progress like usually happens when we download something from Internet, I don't want any dialog to appear, just to show that the file was downloaded like normally happens in any browser like Chrome or IE and then have the choices 'Show in Folder' and things like that, what would I need to add?
public async Task DownloadPdf()
{
DropboxClient client2 = new DropboxClient("cU5M-a4exaAAAAAAAAABDVZsKdpPteNmwHslOeFEo-HByuOr4v4ONvXoAMCFyOXH");
string folder = "MyFolder";
string file = "Test PDF.pdf";
using (var response = await client2.Files.DownloadAsync("/" + folder + "/" + file))
{
using (var fileStream = System.IO.File.Create(#"C:\Users\User\Downloads\Test.pdf"))
{
(await response.GetContentAsStreamAsync()).CopyTo(fileStream);
}
}
}
I have a asp.net core project with an API that returns a file:
[HttpGet("{id}")]
public IActionResult Get(int id) {
byte[] fileContent = READ_YOUR_FILE();
FileContentResult result = new FileContentResult(fileContent, "application/octet-stream") {
FileDownloadName = id.ToString()
};
return result;
}
If I access in my browser the URL from this API (myapp/api/mycontroller/id), then I can see the file downloading.