Well this is a concept and was trying to implement the same in VF. In salesforce Attachments are served with content-disposition = inline, this makes the attachment to display in the browser.

Now plan was to change the content-disposition to attachment by a "Proxy VF Page". The code looks something like this

public Pagereference downloadit() {
    Pagereference pageRef = new Pagereference('https://c.ap1.content.force.com/servlet/servlet.FileDownload?file=00P90000006T0ZH');
    pageref.getHeaders().put('content-disposition', 'attachment; filename=' + 'myfile.png');
    return pageref;

<apex:page controller="AttachmentDownloadProxy_Con" action="{!downloadIt}">


But it doesn't seem to work. The file gets downloaded but seems to be corrupted. Any Idea ?

On checking the file source, this is what I got

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">


        if (this.SfdcApp && this.SfdcApp.projectOneNavigator) {
        } else
         if (window.parent.location.replace) {
        } else {;
            window.parent.location.href = 'https://c.ap1.content.force.com/servlet/servlet.FileDownload?file=00P90000006T0ZH';



1 Answer 1


I think you'll find the contents of your file is actually HTML for a client-side redirect!

Might be tricky to "proxy" the file in this way, but you can change the Content-Type of your attachment to application/octet-stream to force download instead of display:

Try this:

Attachment attachment = new Attachment(
    Id = '00P90000006T0ZH',
    ContentType = 'application/octet-stream'

update attachment;

then link to it as normal and you'll get it as a downloaded file.

  • Well I will try this one. But was wondering if there is way to do it without actually updating the attachment. I was planning to just override the content disposition. By the way I added the source of the file, seems like html is being downloaded
    – Avidev9
    Dec 19, 2013 at 9:05
  • Tried doing the contenttype update doesnt seem to work
    – Avidev9
    Dec 19, 2013 at 9:10
  • If the file isn't binary, you could select its body out as a Blob and then put it in an apex:outputText with escape="false" on your proxy page. But if the Blob contains any non-UTF8 characters it will barf... Dec 19, 2013 at 9:13
  • Did a check again it doesnt seem to work for me.By the way I have a PNG file in the attachment. Well the file is a binary file, it can be PDF or Image. Event after the Update the attachment(PNG) opens in the browser.
    – Avidev9
    Dec 19, 2013 at 9:20
  • "Doesn't work" - details? Dec 19, 2013 at 9:21

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