PHP Page Blank - Not understanding scopes - php

Question

So, simply put, I feel like this code should work. Literally at this moment I am just trying to create a PHP class that takes in some information and runs a command against the database. I know the command works so it's not that, it something to do with the scope of my variables.
I'm new to PHP, and it's been interesting to handle.
<?php
require __DIR__ . '/../bin/composer/vendor/autoload.php';
$cx = new Customer();
$cx->WriteCxToDB();
class Customer {
public $database = new medoo([
'database_type'=>'mysql',
'database_name'=>'dbname',
'server'=>'localhost',
'username'=>'dbusername',
'password'=>'dbpassword',
'charset'=>'utf8'
]);
public function WriteCxToDB(){
global $database;
if($database->has("customer", [
"OR"=>[
"username"=>"cxusername",
"email"=>"email#gmail.com"
]
]))
{
echo "User already exists";
}else{
$database->insert("customer", [
"username"=>"username",
"keyword"=>"keyword",
"email"=>"email#gmail.com",
"phone"=>"444-444-4444",
"first_name"=>"First",
"last_name"=>"Last"
]);
echo "User added";
}
echo "Done";
}
}
?>
I am using composer and medoo to do this database entry. I know the database code works because I've ran it on it's own and it runs fine.
What I'm struggling with the seems to be the variable $database in the code. The function call works if I remove that variable from the mix. I feel like I'm just not understanding where I am supposed to declare the variable / how to reference it from within / outside the function. Thanks.

Answer 1

As suggested in the previous example you should be using something like this and pass a db connection into the class, extending a base class would allow reuse of the db connection:
private $database;
public function __construct($db_connection = null){
//do stuff or set db
$this->database = $this->db_connect;
}
OR make a method in the class to do it
private function db_connect(){
return new medoo([
// required
'database_type' => 'mysql',
'database_name' => 'name',
'server' => 'localhost',
'username' => 'your_username',
'password' => 'your_password',
'charset' => 'utf8',
]);
}
to check consider catching the errors. Using a unique or primary key on the DB would be a safer way of doing this otherwise you have to do validation and searching on the DB. Add the keys and check for duplicate errors.
if($database->error()){
//deal with return or pass to logging
}

Answer 2

The problem here is the use of global scope. Instead of:
global $database;
if($database->has("customer",
use
if($this->database->has("customer",
you could also consider instantiating $database in the constructor, i.e.
private $database;
public function __construct() {
$this->database = new medoo([args....