How can I return a pdf from a web request in ASP.NET? - asp.net

Simply put, I'd like someone to be able to click a link, and get a one-time-use pdf. We have the library to create PDF files, so that's not an issue.
We could generate a link to an aspx page, have that page generate the pdf, save the pdf to the filesystem, and then Response.Redirect to the saved pdf. Then we'd somehow have to keep track of and clean up the PDF file.
Since we don't ever need to keep this data, what I'd like to do instead, if possible, is to have the aspx page generate the pdf, and serve it directly back as a response to the original request. Is this possible?
(In our case, we're using C#, and we want to serve a pdf back, but it seems like any solution would probably work for various .NET languages and returned filetypes.)

Assuming you can get a byte[] representing your PDF:
Response.Clear();
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition",
"attachment;filename=\"FileName.pdf\"");
Response.BinaryWrite(yourPdfAsByteArray);
Response.Flush();
Response.End();

Look at how HTTP works. The client (=browser) doesn't rely on extensions, it only wants the server to return some metadata along with the document.
Metadata can be added with Response.AddHeader, and one 'metadata line' consists of Name and Value.
Content-Type is the property you are interested in, and the value is MIME type of the data (study: RFC1945 for HTTP headers, google for MIME type).
For ordinal aspx pages (html, ....) the property is 'text/html' (not so trivial, but for this example it is enough.). If you return JPG image, it can have name 'image.gif', but as long as you send 'image/jpeg' in Content-Type, it is processed as JPG image.
Content-type for pdf is 'application/pdf'.
The browser will act according to default behaviour, for example, with Adobe plugin, it will display the PDF in it's window, if you don't have any plugin for PDF, it should download the file, etc..
Content-Disposition header says, what you should do with the data. If you want explicitly the client to 'download' some HTML/PDF/whatever, and not display it by default, value 'attachment' is what you want. It should have another parameter, (as suggested by Justin Niessner), which is used in case of something like:
http://server/download.aspx?file=11 -> Content-Disposition: attachment;filename=file.jpg says, how the file should be by default named.

Related

Providing PDF specific parameters in an ASP.NET Generic Handler writing a PDF BLOB stream

EDIT: modified Title to be more specific
I've created a generic handler in VS2012 using their basic template as a starting point and modified it to grab a pdf from our sqlserver. The primary code block is this:
buffer = DirectCast(rsp.ScalarValue, Byte())
context.Response.ContentType = "application/pdf"
context.Response.OutputStream.Write(buffer, 0, buffer.Length)
context.Response.Flush()
And this works fine to display the BLOB as a pdf using whichever pdf plugin is installed on any given browser.
My Question: How can I modify the handler to write Adobe PDF specific parameters to the output? Specifically I'm trying to set width='fit' such that the output PDF stream will autofit the document to the width of the popup window.
NB: Writing the BLOB to a pdf file and serving the PDF is not an option.
Thanks in advance for any advice or links
I don't think there's anything that you can do in your handler. According to that document PDF viewers can examine the URL that was used to open the PDF but there are no HTTP headers that you can set. So you'll need to modify the thing that links to your handler to have those parameters in place. Alternatively, you could build a pre-handler that HTTP redirects to your new handler with those parameters in place.
Also, that document was written in 2007 and was intended for Adobe Acrobat and Adobe Reader. Most modern browsers ship with their own internal PDF viewer these days so unless you are only targeting Adobe your efforts might be wasted.

"Save As" popup in response to a POST request?

Is it possible to get the browser to popup its Save As... dialog when doing a POST (rather than GET) request?
Using the Spring framework, I'm trying to build a service that will receive some data (a two-dimensional json array), and produce an Excel file that the user is prompted to download.
By doing a GET request, eg by browsing directly to my URL, I can get the browser to display the popup by setting headers similar to this:
response.setHeader("Content-Disposition", "attachment; filename=" + fileName)
response.setContentType("application/vnd.ms-excel")
I need to allow the client to post the data that will be used to build the Excel file though, which implies a POST request. The same headers are returned, but no popup.
Is there a way to achieve this, or does the popup appear only for GET requests?
I'm thinking I could do a two-step process; 1) allow the client to POST the data, and return some sort of reference key, 2) allow the client to do a GET request and include the key, and return the relevant headers to cause the browser to popup the dialog.
Any other thoughts on how to do this?
Thanks
It's possible. I'm not sure what I did wrong the first time I tried it out.

Render multiple PDF to browser with Report VIewer - ASP.NET

Current situation
I have ASP.NET web application that render PDF for users using MS Report Viewer. The PDF is rendered with this method:
Byte pdfByte = Byte();
pdfByte = ReportViewer.LocalReport.Render("PDF", Nothing, mimeType, encoding, extensions, stream, warning)
And send to browser as an attachment with response object:
Response.Clear()
Response.ContentType = mimeType
Response.AddHeader("content-disposition", "attachment; filename=myfile." + extension)
Response.BinaryWrite(pdfByte)
Response.Flush()
Response.End()
This work great! The user browser will get the PDF as download-able attachment.
What I am trying to achieve
Render multiple PDF and send all of them separately to user's browser. User will get separate PDF documents. It doesn't matter whether they will get them all at once or one by one.
The problem
The problem is after Response.End() the next line of code is not executed. I have tried to store the pdfByte object in session, looping through it and send them to user's browser with Response object but after the first PDF get sent then it stop.
I have also tried removing Response.End() thinking the code will keep running but still it stop after the first PDF get sent.
Please advice any workaround or tips. Thanks!
You cannot send multiple files (as separate entities) in a single HTTP response (the protocol does not support it. However, what you can do is to archive all files together and send the that single zip (or whatever format you want) to the client.
You can use libraries such as DotNetZip/SharpZipLib to combine (and compress) files together. Based on library API, you may need to save PDF files to disk before adding to zip file. Also do not forget to change your content type appropriate while sending the zip file to client.
Yet another alternative is to provide user with a page having multiple links to download files. It may mean that you either have to store your PDFs for some time so that they can served later (via links) or make link point to a handler that will re-run the report again to get the PDF out of it.
Admittedly the method I'm using doesn't feel very elegant, but here's what I'm doing:
create one IFRAME on the page for each document you want to send to the client (maybe create the IFRAMEs dynamically in server-side code if the number of documents is variable);
create a HttpHandler that generates the PDF documents, depending on a parameter you're passing in through the QueryString, just like you're doing above;
set the src on all IFRAMES to the URL of the HttpHandler with the appropriate parameters attached.
Of course the HttpHandler needs to do implement security logic, if required.
This works quite beautifully: If I want to send 3 documents, I create 3 IFRAMEs, set their src, and the user will see 3 "Save As..." dialogs pop up.

Getting content-type in .ashx from uploadify

I able to upload my file through uploadify + .ashx, but the problem is I always get ContentType = application/octet-stream
Lets say I upload an image, I expected to return me "image/pjpeg", but it always return "application/octet-stream" no matter what file I uploaded.
Please advice how to get the correct contentType in .ashx
I believe that most probably content type is getting set by browser. Regardless, different browsers may set different content type for different files - and they may fall back to generic content type such as "application/octet-stream" for any binary file (pdf, zip, doc, xls). Its possible that one browser would report docx as "application/vnd.openxmlformats" while other as ""application/x-zip-compressed" and yet another as "application/octet-stream". And yet all of them are correct, because docx are binary file and are compressed (zip) files.
In short, my suggestion is that you should not rely on the content type sent by client (beyond certain extent such as deciding whether its text, html or binary etc) and rather use server side sniffing logic to determine type of file content. Simple sniffing can be based on file extension while more robust implementation will loot at actual file contents where typically first few bytes of file indicate the file type.

"name" web pdf for better default save filename in Acrobat?

My app generates PDFs for user consumption. The "Content-Disposition" http header is set as mentioned here. This is set to "inline; filename=foo.pdf", which should be enough for Acrobat to give "foo.pdf" as the filename when saving the pdf.
However, upon clicking the "Save" button in the browser-embedded Acrobat, the default name to save is not that filename but instead the URL with slashes changed to underscores. Huge and ugly. Is there a way to affect this default filename in Adobe?
There IS a query string in the URLs, and this is non-negotiable. This may be significant, but adding a "&foo=/title.pdf" to the end of the URL doesn't affect the default filename.
Update 2: I've tried both
content-disposition inline; filename=foo.pdf
Content-Type application/pdf; filename=foo.pdf
and
content-disposition inline; filename=foo.pdf
Content-Type application/pdf; name=foo.pdf
(as verified through Firebug) Sadly, neither worked.
A sample url is
/bar/sessions/958d8a22-0/views/1493881172/export?format=application/pdf&no-attachment=true
which translates to a default Acrobat save as filename of
http___localhost_bar_sessions_958d8a22-0_views_1493881172_export_format=application_pdf&no-attachment=true.pdf
Update 3: Julian Reschke brings actual insight and rigor to this case. Please upvote his answer.
This seems to be broken in FF (https://bugzilla.mozilla.org/show_bug.cgi?id=433613) and IE but work in Opera, Safari, and Chrome. http://greenbytes.de/tech/tc2231/#inlwithasciifilenamepdf
Part of the problem is that the relevant RFC 2183 doesn't really state what to do with a disposition type of "inline" and a filename.
Also, as far as I can tell, the only UA that actually uses the filename for type=inline is Firefox (see test case).
Finally, it's not obvious that the plugin API actually makes that information available (maybe someboy familiar with the API can elaborate).
That being said, I have sent a pointer to this question to an Adobe person; maybe the right people will have a look.
Related: see attempt to clarify Content-Disposition in HTTP in draft-reschke-rfc2183-in-http -- this is early work in progress, feedback appreciated.
Update: I have added a test case, which seems to indicate that the Acrobat reader plugin doesn't use the response headers (in Firefox), although the plugin API provides access to them.
Set the file name in ContentType as well. This should solve the problem.
context.Response.ContentType = "application/pdf; name=" + fileName;
// the usual stuff
context.Response.AddHeader("content-disposition", "inline; filename=" + fileName);
After you set content-disposition header, also add content-length header, then use binarywrite to stream the PDF.
context.Response.AddHeader("Content-Length", fileBytes.Length.ToString());
context.Response.BinaryWrite(fileBytes);
Like you, I tried and tried to get this to work. Finally I gave up on this idea, and just opted for a workaround.
I'm using ASP.NET MVC Framework, so I modified my routes for that controller/action to make sure that the served up PDF file is the last part of the location portion of the URI (before the query string), and pass everything else in the query string.
Eg:
Old URI:
http://server/app/report/showpdf?param1=foo&param2=bar&filename=myreport.pdf
New URI:
http://server/app/report/showpdf/myreport.pdf?param1=foo&param2=bar
The resulting header looks exactly like what you've described (content-type is application/pdf, disposition is inline, filename is uselessly part of the header). Acrobat shows it in the browser window (no save as dialog) and the filename that is auto-populated if a user clicks the Acrobat Save button is the report filename.
A few considerations:
In order for the filenames to look decent, they shouldn't have any escaped characters (ie, no spaces, etc)... which is a bit limiting. My filenames are auto-generated in this case, and before had spaces in them, which were showing up as '%20's in the resulting save dialog filename. I just replaced the spaces with underscores, and that worked out.
This is by no names the best solution, but it does work. It also means that you have to have the filename available to make it part of the original URI, which might mess with your program's workflow. If it's currently being generated or retrieved from a database during the server-side call that generates the PDF, you might need to move the code that generates the filename to javascript as part of a form submission or if it comes from a database make it a quick ajax call to get the filename when building the URL that results in the inlined PDF.
If you're taking the filename from a user input on a form, then that should be validated not to contain escaped characters, which will annoy users.
Hope that helps.
Try placing the file name at the end of the URL, before any other parameters. This worked for me.
http://www.setasign.de/support/tips-and-tricks/filename-in-browser-plugin/
In ASP.NET 2.0 change the URL from
http://www. server.com/DocServe.aspx?DocId=XXXXXXX
to
http://www. server.com/DocServe.aspx/MySaveAsFileName?DocId=XXXXXXX
This works for Acrobat 8 and the default SaveAs filename is now MySaveAsFileName.pdf.
However, you have to restrict the allowed characters in MySaveAsFileName (no periods, etc.).
Apache's mod_rewrite can solve this.
I have a web service with an endpoint at /foo/getDoc.service. Of course Acrobat will save files as getDoc.pdf. I added the following lines in apache.conf:
LoadModule RewriteModule modules/mod_rewrite.so
RewriteEngine on
RewriteRule ^/foo/getDoc/(.*)$ /foo/getDoc.service [P,NE]
Now when I request /foo/getDoc/filename.pdf?bar&qux, it gets internally rewritten to /foo/getDoc.service?bar&qux, so I'm hitting the correct endpoint of the web service, but Acrobat thinks it will save my file as filename.pdf.
If you use asp.net, you can control pdf filename through page (url) file name.
As other users wrote, Acrobat is a bit s... when it choose the pdf file name when you press "save" button: it takes the page name, removes the extension and add ".pdf".
So /foo/bar/GetMyPdf.aspx gives GetMyPdf.pdf.
The only solution I found is to manage "dynamic" page names through an asp.net handler:
create a class that implements IHttpHandler
map an handler in web.config bounded to the class
Mapping1: all pages have a common radix (MyDocument_):
<httpHandlers>
<add verb="*" path="MyDocument_*.ashx" type="ITextMiscWeb.MyDocumentHandler"/>
Mapping2: completely free file name (need a folder in path):
<add verb="*" path="/CustomName/*.ashx" type="ITextMiscWeb.MyDocumentHandler"/>
Some tips here (the pdf is dynamically created using iTextSharp):
http://fhtino.blogspot.com/2006/11/how-to-show-or-download-pdf-file-from.html
Instead of attachment you can try inline:
Response.AddHeader("content-disposition", "inline;filename=MyFile.pdf");
I used inline in a previous web application that generated Crystal Reports output into PDF and sent that in browser to the user.
File download dialog (PDF) with save and open option
Points To Remember:
Return Stream with correct array size from service
Read the byte arrary from stream with correct byte length on the basis of stream length.
set correct contenttype
Here is the code for read stream and open the File download dialog for PDF file
private void DownloadSharePointDocument()
{
Uri uriAddress = new Uri("http://hyddlf5187:900/SharePointDownloadService/FulfillmentDownload.svc/GetDocumentByID/1/drmfree/");
HttpWebRequest req = WebRequest.Create(uriAddress) as HttpWebRequest;
// Get response
using (HttpWebResponse httpWebResponse = req.GetResponse() as HttpWebResponse)
{
Stream stream = httpWebResponse.GetResponseStream();
int byteCount = Convert.ToInt32(httpWebResponse.ContentLength);
byte[] Buffer1 = new byte[byteCount];
using (BinaryReader reader = new BinaryReader(stream))
{
Buffer1 = reader.ReadBytes(byteCount);
}
Response.Clear();
Response.ClearHeaders();
// set the content type to PDF
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition", "attachment;filename=Filename.pdf");
Response.Buffer = true;
Response.BinaryWrite(Buffer1);
Response.Flush();
// Response.End();
}
}
I believe this has already been mentioned in one flavor or another but I'll try and state it in my own words.
Rather than this:
/bar/sessions/958d8a22-0/views/1493881172/export?format=application/pdf&no-attachment=true
I use this:
/bar/sessions/958d8a22-0/views/1493881172/NameThatIWantPDFToBe.pdf?GeneratePDF=1
Rather than having "export" process the request, when a request comes in, I look in the URL for GeneratePDF=1. If found, I run whatever code was running in "export" rather than allowing my system to attempt to search and serve a PDF in the location /bar/sessions/958d8a22-0/views/1493881172/NameThatIWantPDFToBe.pdf. If GeneratePDF is not found in the URL, I simply transmit the file requested. (note that I can't simply redirect to the file requested - or else I'd end up in an endless loop)
You could always have two links. One that opens the document inside the browser, and another to download it (using an incorrect content type). This is what Gmail does.
For anyone still looking at this, I used the solution found here and it worked wonderfully. Thanks Fabrizio!
The way I solved this (with PHP) is as follows:
Suppose your URL is SomeScript.php?id=ID&data=DATA and the file you want to use is TEST.pdf.
Change the URL to SomeScript.php/id/ID/data/DATA/EXT/TEST.pdf.
It's important that the last parameter is the file name you want Adobe to use (the 'EXT' can be about anything). Make sure there are no special chars in the above string, BTW.
Now, at the top of SomeScript.php, add:
$_REQUEST = MakeFriendlyURI( $_SERVER['PHP\_SELF'], $_SERVER['SCRIPT_FILENAME']);
Then add this function to SomeScript.php (or your function library):
function MakeFriendlyURI($URI, $ScriptName) {
/* Need to remove everything up to the script name */
$MyName = '/^.*'.preg_quote(basename($ScriptName)."/", '/').'/';
$Str = preg_replace($MyName,'',$URI);
$RequestArray = array();
/* Breaks down like this
0 1 2 3 4 5
PARAM1/VAL1/PARAM2/VAL2/PARAM3/VAL3
*/
$tmp = explode('/',$Str);
/* Ok so build an associative array with Key->value
This way it can be returned back to $_REQUEST or $_GET
*/
for ($i=0;$i < count($tmp); $i = $i+2){
$RequestArray[$tmp[$i]] = $tmp[$i+1];
}
return $RequestArray;
}//EO MakeFriendlyURI
Now $_REQUEST (or $_GET if you prefer) is accessed like normal $_REQUEST['id'], $_REQUEST['data'], etc.
And Adobe will use your desired file name as the default save as or email info when you send it inline.
I was redirected here because i have the same problem. I also tried Troy Howard's workaround but it is doesn't seem to work.
The approach I did on this one is to NO LONGER use response object to write the file on the fly. Since the PDF is already existing on the server, what i did was to redirect my page pointing to that PDF file. Works great.
http://forums.asp.net/t/143631.aspx
I hope my vague explanation gave you an idea.
Credits to Vivek.
Nginx
location /file.pdf
{
# more_set_headers "Content-Type: application/pdf; name=save_as_file.pdf";
add_header Content-Disposition "inline; filename=save_as_file.pdf";
alias /var/www/file.pdf;
}
Check with
curl -I https://example.com/file.pdf
Firefox 62.0b5 (64-bit): OK.
Chrome 67.0.3396.99 (64-Bit): OK.
IE 11: No comment.
Try this, if your executable is "get.cgi"
http://server,org/get.cgi/filename.pdf?file=filename.pdf
Yes, it's completely insane. There is no file called "filename.pdf" on the server, there is directory at all under the executable get.cgi.
But it seems to work. The server ignores the filename.pdf and the pdf reader ignores the "get.cgi"
Dan

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