Question

EDIT

From what I have learned (from comments by nico_ekito) it is not possible to use ajax call to download a file. The solution is to create a hidden <iframe> that will download the file, described here.

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Problem:
The browser doesn’t show download dialog. Any browser – ff, opera, chrome, safari, ie.

I read the docs about serving files, found this question and, based on this, wrote:

Controller.response().setContentType("text/csv");
Controller.response().setHeader("Content-Disposition", "attachment;filename=public/export/filename.csv");
Controller.response().setHeader("Cache-control", "private");

return ok(CSV.export(data, filename));

Where CSV is a class:

public class CSV{
    public static File export(Map<String, String> data, String filename){
        String csv = data.get("data[saveMe]");

        try {
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("public/export/" + filename), "UTF-8"));
            bw.write(csv);
            bw.newLine();
            bw.flush();
            bw.close();
        }catch(UnsupportedEncodingException e){}
        catch(FileNotFoundException e){}
        catch(IOException e){}

        File downloadMe = new File("public/export/" + filename);

        return downloadMe;
    }
}

On client side, I use dojo to send POST request (I also tried with GET, result is the same):

xhr.post({
    url: '/exportData/',
    content: {
        saveMe: str
    }
}).then(function(response){
    //do sth 
});

Response headers look like that:

Cache-Control       private
Content-Disposition attachment;filename=public/export/filename.csv
Content-Type        text/csv
Transfer-Encoding   chunked

POST tab in firebug shows proper data in proper csv format. To format data with csv style I use dojox/grid/enhanced/plugins/exporter/CSVWriter

Answer 1

I think it is not possible to download a file from an Ajax request, see this question: Allow User to Download File using Ajax

You should either use an iframe as suggested in the question, or use a standard HTML form containing your data, and do a post on this form.