Grails File Download

Question

Hi there,

I'm trying to craete a site which allows users to upload any file type they like. I've implemented this feature fine, and the file is held on the server. Later on they can download the file to view, but i'm having trouble getting it to work.

I've used any examples I can get hold of but they all tend to use text files as examples. My problem is that pdf's and many other file types aren't downloading properly. They seem to download fine, but none of the files will open successfully. Comparing the files, it seems most of the files content is correct, but certain parts are not.

Here's my groovy code:

def file = new File(params.fileDir)    
response.setContentType("application/octet-stream")
response.setHeader("Content-disposition", "filename=${file.getName()}")
response.outputStream << file.text
return

This code is held inside a controller which is called by a download link. I've tried playing around with different contentTypes, but I don't know which I could use for any type - is there one? Anything I try doesn't solve the problem.

Thanks for your help.

Answer 1

The problem is that you read the content of the file into a String by using "file.text". The content of the file is converted with the system character encoding even if the content is binary, not text (eg. PDF files are binary) and sent to the client using the response encoding and thereby modifing the binary content. You should rather use a different approach like this:

def file = new File(params.fileDir)    
response.setContentType("application/octet-stream")
response.setHeader("Content-disposition", "attachment;filename=${file.getName()}")

response.outputStream << file.newInputStream() // Performing a binary stream copy

Answer 2

I haven't had chance to test your solution, but while I'm here.

Should the MIME type "application/octet-stream" work for any file type? As the user can upload any file type, I don't want to have to try and work out which MIME type to use per file download, it seems more hassle than its worth!

Also, the fileName i'm setting in the header - if the name has a space the rest of the name is cut off.

e.g. "random file.txt" is uploaded.
on download, a file called "random" is asked to be saved.

Is there an easy way to resolve this, or should I just replace spaces with underscores or something?

Cheers

Answer 3

..and return null from the action in order to stop page reload.