Array_push in for loop giving null response - php

Question

Hello I am trying to push in an array using array_push but I am getting the value of the first index then after that all I am getting a null response, I am not getting where I have done a mistake.I am getting the values properly but in array_push there is some mistake which is in for loop.
Here is my code :
function actioncouponcsv_download() {
$this->layout = false;
foreach (Yii::app()->log->routes as $route) {
if ($route instanceof CWebLogRoute || $route instanceof CFileLogRoute || $route instanceof YiiDebugToolbarRoute) {
$route->enabled = false;
}
}
$dateRange = json_decode($_POST['dateRange'], true);
$start = $dateRange['start'];
$end = $dateRange['end'];
$validity = $_POST['validity'];
$limit = isset($_REQUEST['limit']) && trim($_REQUEST['limit']) ? $_REQUEST['limit'] : 0;
$studio_id = Yii::app()->user->studio_id;
if (isset($_GET['type']) && intval($_GET['type']) ==2) {
$couponobj = new CouponSubscription();
$getcouponobj = $couponobj->getcoupon_data($studio_id,$start,$end,$validity);
$k = 0;
$title_addon = "\t" . "Discount Cycle" . "\t" . "Extend free trail";
$data_addon = "\t" . $getcouponobj[$k]['discount_multiple_cycle'] . "\t" . $getcouponobj[$k]['extend_free_trail'];
} else {
$title_addon = "";
$data_addon = "";
$couponobj = new Coupon();
$getcouponobj = $couponobj->getcoupon_data($studio_id,$limit,1);
}
//$Coupon = Coupon::model()->find('studio_id=:studio_id', array(':studio_id' => $studio_id));
$dataCsv = '';
if ($getcouponobj) {
$headings = "Sl no" . "\t" . "Coupon" . "\t" . "Coupon Type" . "\t" . "Used by a single user" . "\t" . "Valid" . "\t" . "Used" . "\t" . "User" .$title_addon. "\t" . "Used Date". "\t" . "Content Category". "\t" . "Content"."\n";
$i = 1;
$dataCSV[] = Array();
$j = 0;
for ($k = 0; $k < count($getcouponobj); $k++) {
$userList = '-';
if ($getcouponobj[$k]['used_by'] != '0') {
if ($getcouponobj[$k]['coupon_type'] == 1) {
$userList = '';
$userIdList = explode(",", $getcouponobj[$k]['used_by']);
foreach ($userIdList as $userIdListKey => $userIdListVal) {
if ($userIdListKey == 0) {
$userList .= Yii::app()->webCommon->getuseremail($userIdListVal);
} else {
$userList .= " | " . Yii::app()->webCommon->getuseremail($userIdListVal);
}
}
} else {
$userList = Yii::app()->webCommon->getuseremail($getcouponobj[$k]['used_by']);
}
}
if($getcouponobj[$k]['is_all']!=1){
if($getcouponobj[$k]['content_category']==1){
$cont_cat = "Digital";
$content_str = Coupon::model()->getContentInfo($getcouponobj[$k]['specific_content']);
$cont_str = $content_str;
}else if($getcouponobj[$k]['content_category']==2){
$cont_cat = "Physical";
$content_str = Coupon::model()->getContentInfoPhysical($getcouponobj[$k]['specific_content']);
$cont_str = $content_str;
}else{
$cont_cat = "All";
$cont_str = "All";
}
}else{
$cont_cat = "All";
$cont_str = "All";
}
#echo $getcouponobj[$k]['coupon_code'];
array_push($dataCSV[$j],$i);
array_push($dataCSV[$j],$getcouponobj[$k]['coupon_code']);
array_push($dataCSV[$j],(($getcouponobj[$k]['coupon_type'] == 1) ? 'Multi-use' : 'Once-use'));
array_push($dataCSV[$j],(($getcouponobj[$k]['user_can_use'] == 1) ? 'Multiple times' : 'Once'));
array_push($dataCSV[$j],(($getcouponobj[$k]['used_by'] == 0) ? 'Yes' : 'No'));
array_push($dataCSV[$j],(($getcouponobj[$k]['used_by'] == 0) ? '-' : 'Yes'));
array_push($dataCSV[$j],$userList);
array_push($dataCSV[$j],$getcouponobj[$k]['discount_multiple_cycle']);
array_push($dataCSV[$j],$getcouponobj[$k]['extend_free_trail']);
array_push($dataCSV[$j],(($getcouponobj[$k]['cused_date'] == 0) ? '-' : $getcouponobj[$k]['cused_date']));
array_push($dataCSV[$j],$cont_cat);
array_push($dataCSV[$j],$cont_str);
$j++;
//$dataCsv .= $i . "\t" . $getcouponobj[$k]['coupon_code'] . "\t" . (($getcouponobj[$k]['coupon_type'] == 1) ? 'Multi-use' : 'Once-use') . "\t" . (($getcouponobj[$k]['user_can_use'] == 1) ? 'Multiple times' : 'Once') . "\t" . (($getcouponobj[$k]['used_by'] == 0) ? 'Yes' : 'No') . "\t" . (($getcouponobj[$k]['used_by'] == 0) ? '-' : 'Yes') . "\t" . $userList .$data_addon. "\t" . (($getcouponobj[$k]['cused_date'] == 0) ? '-' : $getcouponobj[$k]['cused_date'])."\t" .$cont_cat ."\t".$cont_str."\n";
$i = $i+1;
}
}
print_r(json_encode($dataCSV));
}
PS: I am getting the values. Any help will be highly appreciated.

Answer 1

Well, first thing i see wrong is the way you declare your array:
$dataCSV[] = Array();
$array[] = Means that you are adding a new value to an existing array. To declare your array you should use
$dataCSV = array();
Also, this code:
array_push($dataCSV[$j],$i);
means that you are adding a new value to your $dataCSV[$j] array, but this is never declared as an array, so first thing would be to do
$dataCSV[$j] = new array();
Your code is really long and complicated, those are only examples of issues i see in there.