php - Download CSV file using "AJAX"

Question

I'm trying to accomplish a fairly simple task for my website, but I"m not sure exactly how to go about it. I want the user to be viewing a table, then click a button, at which point the user can save the contents of that table as a csv file. This request can sometimes be quite complicated so I generate a progress page to alert the user.

I have most things figured out except actually generating the csv file. (I use jQuery and PHP)

the jQuery code run on click:

hmis_query_csv_export: function(query_name) {
    $.uiLock('<p>Query Loading.</p><img src="/images/loading.gif" />')
    $.get({
        url: '/php_scripts/utils/csv_export.php',
        data: {query_name: query_name},
        success: function(data) {
            $.uiUnlock();
        }
    });}

the relevant PHP:

header("Content-type: text/x-csv");
header("Content-Disposition: attachment; filename=search_results.csv");
//
//Generate csv
//
echo $csvOutput
exit();

What this does is sends the text as the PHP file, but it's doesn't generate a download. What am I doing wrong?

Answer 1

If you are forcing a download, you can redirect the current page to the download link. Since the link will generate a download dialog, the current page (and its state) will be kept in place.

Basic approach:

$('a#query_name').click(function(){
    $('#wait-animation').show();
    document.location.href = '/php_scripts/utils/csv_export.php?query_name='+query_name;
    $('#wait-animation').hide();
});

More complicated:

$('a#query_name').click(function(){
    MyTimestamp = new Date().getTime(); // Meant to be global var
    $('#wait-animation').show();
    $.get('/php_scripts/utils/csv_export.php','timestamp='+MyTimestamp+'&query_name='query_name,function(){
        document.location.href = '/php_scripts/utils/csv_export.php?timestamp='+MyTimestamp+'&query_name='+query_name;
        $('#wait-animation').hide();
    });
});

At PHP script:

@header("Last-Modified: " . @gmdate("D, d M Y H:i:s",$_GET['timestamp']) . " GMT");
@header("Content-type: text/x-csv");
// If the file is NOT requested via AJAX, force-download
if(!isset($_SERVER['HTTP_X_REQUESTED_WITH']) || strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) != 'xmlhttprequest') {
    header("Content-Disposition: attachment; filename=search_results.csv");
}
//
//Generate csv
//
echo $csvOutput
exit();

The URL for both requests must be the same to trick the browser not to start a new download at document.location.href, but to save the copy at the cache. I'm not totally sure about it, but seems pretty promising.