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WebObjects/Web Applications/Development/Examples/Return a File

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To return a file from a hyperlink, the easiest way seems to be over-riding appendToResponse in a WOComponent to return that file as a response, rather than letting the WOComponent generate its own response from .html/.wod files: 

 public void appendToResponse(WOResponse aResponse, WOContext aContext) {
   //Use whatever mime-type you need for content-type:
   //"text/csv" is just an example. 
   aResponse.setHeader("text/csv", "content-type"); 
   //Assuming 'data' is a Java byte[] array. But
   //You can do whatever you want to wind up with
   //an NSData of content. 
   aResponse.setContent( new NSData( data ) );
   aResponse.setHeader("filename=MyFilename.xls", "Content-Disposition");
   //or, if you want the link to "force" a SaveAs dialog...
   //aResponse.setHeader("attachment;filename=MyFilename.xls", "Content-Disposition");

Someone else reports: We have the following code for downloading a generated pdf... 

       public void appendToResponse(WOResponse aResponse, WOContext aContext)  {
               super.appendToResponse(aResponse, aContext);
               //aResponse.setHTTPVersion("HTTP/1.1");
               aResponse.disableClientCaching();
               aResponse.removeHeadersForKey("Cache-Control");
               aResponse.removeHeadersForKey("pragma");
               aResponse.setHeader("application/pdf", "content-type");
               aResponse.setHeader("inline; attachment; filename=\"" + fileName + ".pdf\"", "content-disposition");
               aResponse.setHeader(Integer.toString(resultData.length()), "content-length");
               aResponse.setContent(resultData);
   }

The lines of interest for fixing the IE problem (for us at least) were... 

               aResponse.disableClientCaching();
               aResponse.removeHeadersForKey("Cache-Control");
               aResponse.removeHeadersForKey("pragma");

You might want to try: 

   public void appendToResponse( WOResponse r, WOContext c ) { 
      fileName = "test.txt"; 
      r.setHeader( contentType + "; name=\"" + fileName + "\"", "Content-Type" ); 
      r.setHeader( "inline; filename=\"" + fileName + "\"", "Content-Disposition"); 
      r.setContent( data ); 
   }

Although according to RFC2183, your code should work fine, I've found that certain browsers from a monopoly that shall nameless looks only to the old RFC1341 location for the filename, which is in the Content-Type header, not in (or at least just in) the Content-Disposition header.

If you're primarily interested in having them download the file, you might want to make it: 

 public void appendToResponse( WOResponse r, WOContext c ) { 
      fileName = "test.txt"; 
      r.setHeader( contentType + "; name=\"" + fileName + "\"", "Content-Type" ); 
      r.setHeader( "attachment; filename=\"" + fileName + "\"", "Content-Disposition"); 
      r.setContent( data ); 
 }

And another back-and-forth from the mailing list....

I got a problem with display PDF file [....] I can save file successfully by click [save] on Download Message Alert But when I click [open], Acrobat run and display the error message of "There is no such file", failed to open the PDF file.

From: "MacMullin, Jake (DCS)" <MacMullin.Jake@saugov.sa.gov.au>; To: "'Lu Yanmei'" <lu.yanmei@meta.co.jp>, webobjects-dev@omnigroup.com Subject: RE: could not open PDF file Date: Fri, 30 May 2003 09:06:57 +0930

I had the exact same problem. Turned out it has to do with the headers you use. I've found this combination works best: 

 // set the PDF content and header
 response.setContent(outData);
 response.appendHeader("application/pdf", "Content-Type");
 response.appendHeader(outData.length()+"", "Content-Length");
 response.appendHeader("inline;filename=\"file.pdf\"", "Content-Disposition");

And another back-and-forth from the mailing list....

I got a problem to display a PDF file in a browser [....] I can send simple text files to open in a browser but pdf shows up as garbage. I cant depend on the user to have a plugin, is there a way to show it in the browser? Either that or is there a way to convert pdf to html and show that in the browser. 

 r.appendHeader("application/pdf", "Content-type");
 r.setHeader(Integer.toString(myData.length()), "content-length");
 r.appendHeader("application;filename=\"dockconcepts.pdf\"", "Content-Disposition");
 r.appendContentCharacter('\n');
 r.appendContentData(new NSData(myData));

If you want to return a file in response to the submission of a form (and have it work in IE on Windows), you need to change the 'method' of the form from 'POST' to 'GET' by adding a 'method' binding to the form in WOBuilder.

I would strongly recommend to use the setHeader method instead of the appendHeader method to make sure that an existing content-type will be overwritten by the file return component. If a content-type already exists, appendHeader will not change the content type value which could lead to unpredictable results. --Hschottm 14:24, 16 January 2007 (UTC)

Download from subcomponents

edit

If you're trying to do this from a sub-component you need to use setContentInputStream instead of setContent. The documentation for the former says "only the data in the InputStream is returned -- any data that was added or set (either as String or NSData) is ignored", while the latter can be overwritten or appended to later in the page's lifecycle. For example, I have a generic component that runs a report and provides it as a PDF to the user. I want to include the component as follows in my ListPeople page: 

       PrintLink : ReportDownloader {
               title = "Download these results";
               fileName = "PersonList.pdf";
               data = personList.displayedObjects;
               definition = "personlist";
       }

In ReportDownloader.java, doReport() handles the click on the "Download these results" link and builds the report. 

       public void doReport() {
          // ...snip...
          // Run the report and put the resulting PDF into the byte array pendingResponse
          // ...snip...
       }

As described above, the overriden appendToResponse method is responsible for actually writing the report into the response. 

       public void appendToResponse(WOResponse aResponse, WOContext aContext) {
               super.appendToResponse(aResponse, aContext);
               if (pendingResponse != null) {
                       //aResponse.setContent(pendingResponse);
                       ByteArrayInputStream in = new ByteArrayInputStream(pendingResponse);
                       aResponse.setHeader("application/pdf", "Content-type");
                       aResponse.setHeader("inline; filename=" + fileName, "Content-disposition");
                       aResponse.setContentStream(in, 512, (long)pendingResponse.length);
               }
       }

Creating a ByteArrayInputStream and setting the response to use it guarantees that the PDF content is the only content returned in the response, regardless of what the parent page (the one that contains ReportDownloader) tries to render into the response.

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