PHP Page Blank - Not understanding scopes

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.

Whenever you get a blank page in PHP when some output is otherwise expected, check your error logs. Enable display_errors always when developing and testing code - any fatal error should show up immediately. At the top of your script: `error_reporting(E_ALL); ini_set('display_errors', 1);` — Michael Berkowski, Dec 12 '16 at 16:28
I notice you've used `global $database` but you also have a `$database` attribute defined in the class, which would be accessible as `$this->database`... — Michael Berkowski, Dec 12 '16 at 16:30
Instantiating a class instance `$database` when declaring a property does not appear to be one of the examples given at http://php.net/manual/en/language.oop5.properties.php so I would imagine your error reporting is turned off so you need to either turn it on or check your error logs. — MonkeyZeus, Dec 12 '16 at 16:38
Thanks everyone for your comments. All of this helped a ton. I'll go enable error reporting now, and maybe I won't have to ask another question in the future. (wishful thinking) — Entevily, Dec 12 '16 at 17:58

score 2 · Answer 1 · answered Dec 12 '16 at 16:38

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....

score 2 · Accepted Answer · answered Dec 12 '16 at 17:17

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
}

Thanks - creating the constructor seemed to make things work better and I was able to get this working. — Entevily, Dec 12 '16 at 17:58

PHP Page Blank - Not understanding scopes

2 Answers2