Working with PHP global variable - php

Question

I am trying to integrate my regular php build script into wordpress. I am stuck in a place where the function works perfectly before, but not in wordpress environment.
In the code below, I am getting blank array in my ajax request whereas I do have results inside myFunc (I have tested by putting wp_send_json inside).
Do I need to change anything to work with PHP globals in wordpress?
$final = array();
function myFunc(){
global $wpdb;
global $final;
$sql = 'SELECT .......';
$result = $wpdb->get_results($sql);
if($wpdb->num_rows > 0){
foreach ( $result as $row ) {
$final[] = $row->pdate;
}
return true;
}
return false;
}
myFunc();
wp_send_json($final);

Answer 1

You can use following statements to get updated value from function.
$arr = array();
function myFunc($new_arr){
global $wpdb;
$sql = 'SELECT .......';
$result = $wpdb->get_results($sql);
if($wpdb->num_rows > 0){
foreach ( $result as $row ) {
$new_arr[] = $row->pdate;
}
}
//It will return updated array if result having rows.Otherwise return empty array.
return $new_arr;
}
$final = myFunc($arr);
if(!empty($final))//if block will be execute if myFunc doesn't return empty array.
{
wp_send_json($final);
}

Answer 2

That should work but globals are nasty things to use and will often conflict I'd suggest just returning the array from the function.
e.g.
function myFunc(){
global $wpdb;
$final = array();
$sql = 'SELECT .......';
$result = $wpdb->get_results($sql);
if($wpdb->num_rows > 0){
foreach ( $result as $row ) {
$final[] = $row->pdate;
}
return $final;
}
return false;
}
$myFuncReturn = myFunc();
if($myFuncReturn !== false){
wp_send_json($myFuncReturn);
}