Export to CSV exports page code too - php

Question

I have an export function on my website. It exports from a MySQL result query and lets it save the file as CSV locally on user's computer.
Export functionality is almost working, except for one thing. Inside the exported and saved CSV right after all the exported MySQL data at the end the PHP script also includes the entire form's code.
Not sure why.
Export form. Let's you pick what data to export using <select>. This whole code shows up in CSV file after all data:
<div class="btn-group-vertical btn-group-lg btn-block">
<span class="glyphicon glyphicon-step-backward"></span> Back
</div>
<hr />
<?php
// show potential errors / feedback (from registration object)
if (isset($obj1)) {
if ($obj1->errors) {
foreach ($obj1->errors as $error) {
echo $error;
}
}
if ($obj1->messages) {
foreach ($obj1->messages as $message) {
echo $message;
}
}
}
?>
<form name="exportcsvform" method="post" action="admin_export.php" role="form">
<div class="form-group">
<label for="export_data" class="sr-only">Choose:</label>
<select size="1" name="export_data" id="export_data" class="input-lg">
<option value="" selected="selected" disabled>Choose</option>
<?php $obj1->getData(); ?>
</select>
</div>
<div class="form-group">
<button type="submit" class="btn btn-default btn-lg" name="export" id="export"><span class="glyphicon glyphicon-save"></span>Export</button>
</div>
<hr />
</form>
The PHP function that generates the CSV. It's inside a class, let's call it Class1:
private function exportData()
{
if(isset($_POST['export_data'])){
$this->db_connection = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
if (!$this->db_connection->set_charset("utf8")) {
$this->errors[] = $this->db_connection->error;
}
if (!$this->db_connection->connect_errno) {
$export_data_id = $_POST['export_data'];
$sql =<<<EOF
SELECT col1, col2, col3
FROM table1
JOIN table2 ON table2.col0=table1.col0
WHERE table1.col0 = $export_data_id;
EOF;
// output headers so that the file is downloaded rather than displayed
header('Content-Type: text/csv; charset=utf-8');
header('Content-Disposition: attachment; filename=data.csv');
// create a file pointer connected to the output stream
$output = fopen('php://output', 'w');
// output the column headings
fputcsv($output, array('col1','col2','col3'));
$query_export_data = $this->db_connection->query($sql);
$rows = array();
while($r = mysqli_fetch_assoc($query_export_data)){
$rows[] = $r;
}
// loop over the rows, outputting them
foreach ($rows as $r) fputcsv($output, $r);
}else{
// show error
}
}
}
Main PHP file that loads headers, content, footer and is also the action for the export form(admin_export.php):
<?php
// include the configs / constants for the database connection
require_once("config/db.php");
// load the login class
require_once("classes/Login.php");
// create a login object. when this object is created, it will do all login/logout stuff automatically
// so this single line handles the entire login process. in consequence, you can simply ...
$login = new Login();
// only administrators can see
if (login stuff) {
// require once classes here
require_once("classes/User.php");
$user = new User();
require_once("classes/Class1.php");
$class1 = new Class1();
include("includes/header.php");
// include views here
// include("views/admin_whatever_view.php");
include("views/admin_export_view.php");
include("includes/footer.php");
}else{
echo "<h1>Access denied</h1>";
include("views/go_back_view.php");
}
?>

Answer 1

Most likely it's because you need to flush the output buffer.
Here's a simple export CSV function based on an array taken from ExchangeCore blog. Looks like the only difference is the ob_* functions
public function outputCsv($fileName, $assocDataArray)
{
ob_clean();
header('Pragma: public');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Cache-Control: private', false);
header('Content-Type: text/csv');
header('Content-Disposition: attachment;filename=' . $fileName);
if(isset($assocDataArray['0'])){
$fp = fopen('php://output', 'w');
fputcsv($fp, array_keys($assocDataArray['0']));
foreach($assocDataArray AS $values){
fputcsv($fp, $values);
}
fclose($fp);
}
ob_flush();
}