query function not work in php7 - php

Question

first of all, I want to thank you to everyone who gives this post attention. I got a problem when migrating code from php5 to php7. I actually don't know what is going wrong in my code
class database {
public function __construct () {
$conn = mysqli_connect("localhost", "root", "");
mysqli_select_db($conn, 'crm');
}
public function view_chart(){
$data = mysqli_query($conn, "select * from t_chart");
while($d = mysqli_fetch_array($data)){
$hasil[] = $d;
}
return $hasil;
}
foreach($db->view_chart() as $x){
echo "<option value='$x[id_chart_cat]'>$x[chart_name]</option>";
}
the view_chart() not work but it's work in php4 as well. anyone here can tell me what is going wrong with this code? I really appreciate any answer which is related to this question. Thank you.

Answer 1

You have to declare $conn as class member variable so it's accessible from other class functions.
Do:
class database {
public $conn; // added
public function __construct () {
$this->conn = mysqli_connect("localhost", "root", ""); // modified
mysqli_select_db($this->conn, 'crm'); // modified
}
public function view_chart(){
$data = mysqli_query($this->conn, "select * from t_chart"); // modified
while($d = mysqli_fetch_array($data)){
$hasil[] = $d;
}
return $hasil;
}
foreach($db->view_chart() as $x){
echo "<option value='$x[id_chart_cat]'>$x[chart_name]</option>";
}

Answer 2

when I updated my PHP-scripts to PHP7 I had issues with
mysqli_fetch_array()
you should replace it with a function like
mysqli_fetch_assoc()

Answer 3

did you first check and make sure your connection was being made? and how i always did it in 7 was like this
<?php
$servername = "localhost";
$username = "root";
$password = "password";
$dbName = "test";
$conn = new mysqli($servername, $username, $password, $dbName);
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
?>
then you can do
<?php
$query = "SELECT * FROM whatever";
$result = $conn->query($query);
$hasil = [];
?>
then you should be able to just do
while($row = $result->fetch_assoc()){
$hasil[] = $row;
}
return $hasil;
then go into your foreach...not sure if that's what your looking for but hope it helps