I think we need a s:resourceLink tag

[dhinojosa]

I was looking for a way to download a pdf that I have stored on the database which will subsequentially appear in a bean.  I would like the user to download that pdf via a link.  So I went looking through the documentation and the 'Seam in Action' book didn't find what I really needed. 

So I am suggesting that Seam has a <s:resourceLink/> so that we can download stuff from objects within a context. 

As an example, this code would download a specification drawing from any product.  <s:resourceLink/> should act like <s:graphicImage/> except that it would make a resource available for download via link.

<s:resourceLink value="#{product.specification.dataArray}" mimeType="#{product.specification.mimeType}">
   <h:outputText value="Click here to download a pdf of this product"/>
</s:resourceLink>

Let me know if I should JIRA this..

Danno

[cjalmeida]

I vouche for such tag. The code I use looks like a very nasty hack.

FacesContext facesContext = FacesContext.getCurrentInstance();
HttpServletResponse response = (HttpServletResponse) facesContext.getExternalContext().getResponse();
response.setContentType("application/octet-stream");
response.setHeader("Content-disposition", "attachment; filename='myfile.txt'");
OutputStream out = response.getOutputStream();
out.write(data);
out.close();
facesContext.responseComplete();

IMO, you should also especify an optional filename attribute. If it's set, the component should ignore mimeType and return application/octet-stream. According to HTTP specification, the user agent should present the save as dialog instead of trying th o show the file.

[dan.j.allen]

Take a look at chapter 13 again of Seam in Action (13.2.5 Serving dynamic documents). There is an example of how to do this it a fairly elegant way using Seam's DocumentStore component. Granted, it probably would be nice to implement a component that did all of this work automatically, so I think the idea is good, but you can definitely get some mileage out of what Seam has today.

Here's a quick copy-paste taking out of context:

byte[] binaryData = ...;
DocumentData data = new DocumentData("report"
    new DocumentData.DocumentType("pdf", "application/pdf"),
    binaryData);
String docId = documentStore.newId();
documentStore.saveData(docId, data);                         
String documentUrl =
    documentStore.preferredUrlForContent(                    
        data.getBasename(),
        data.getDocumentType().getExtension(),
        docId);
redirect(documentUrl);