PHP代码转换为PHP / MySQLi OOP

Question

today i tried to convert my code to PHP/MySQLi OOP code.

class Database
{
private $host;
private $user;
private $password;
private $db;
private $mysqli;

function __construct()
{
    $this->host = "*****";
    $this->user = "*****";
    $this->password = "******";
    $this->db = "*****";

    $this->mysqli = new mysqli($this->host, $this->user, $this->password, $this->db);

    if (mysqli_connect_errno()):
        printf("Connect failed: %s\n", mysqli_connect_error());
        exit();
    endif;
}
}

This is a script for the query's:

include_once("WD_Config/database.php");

class Adressen_Db
{
function __construct()
{
    $this->database = new Database();
}

public function selecteer()
{
    $query = "SELECT * FROM wd_adressen WHERE verborgen = 0 ORDER BY naam ASC";
    $result = $this->database->mysqli->query($query);

    return $result;
}
}

And this is how i call it.

$adressen = new Adressen_Db;
$adressen_result = $adressen->selecteer();

echo "<p>";
while ($row = $adressen_result->fetch_assoc()):
echo "<a href='http://maps.google.com/?q=".$row['voladres']."'     target='_blank'>".$row['naam']."</a> woonachtig op <i>".$row['voladres']."</i><br>";
endwhile;
echo "</p>";

I alway get a "Call to a member function query() on a non-object". Doesn't matter what i trie ...

Can somebody tell me why that is?

Thanks!

Answer 1

The $mysqli variable in class Database is declared private .

You can access it only through setters and getters.

Answer 2

I think while you definitely need to have $mysqli as public so it can be accessed in the other method, there might be something else, as the error would be something like

trying to access private property in database class

or something like that, whereas your script throws a non-object call error

I think your new Adressen_Db; lacks the parenthesis:

$adressen = new Adressen_Db();

Answer 3

You can replace your code with this:
Config.php

<?php

define("DB_HOST", "localhost");
define("DB_USER", "root");
define("DB_PASS", "");
define("DB_NAME", "your_database_name");

Now include this file in your database file

require_once 'config.php';

Class Database {

    public $host = DB_HOST;
    public $user = DB_USER;
    public $pass = DB_PASS;
    public $dbname = DB_NAME;
    public $link;
    public $error;

    public function __construct() {
        $this->getConnection();
    }

    private function getConnection() {
        $this->link = new mysqli($this->host, $this->user, $this->pass, $this->dbname);
        if (!$this->link) {
            $this->error = "Connection failed" . $this->link->connect_error;
            return false;
        }
    }

    // for only select query
    public function select($query) {
        $result = $this->link->query($query) or
                die($this->link->error . __LINE__);
        if ($result->num_rows > 0) {
            return $result;
        } else {
            return false;
        }
    }

    // for insert, delete and update
    public function myquery($query) {
        $myquery = $this->link->query($query) or
                die($this->link->error . __LINE__);
        if ($myquery) {
            return $myquery;
        } else {
            return false;
        }
    }

}

Now, make your queries like this:

<?php
require_once './lib/Database.php';
?>

<?php

class Admin {

    private $db;

    public function __construct() {
        $this->db = new Database();
    }

    public function getData(){
        $query = "SELECT * FROM admin";
        $result = $this->db->select($query);
        if($result != false){
            while($row = $result->fetch_assoc()){
                // do your thing
            }
        }
    }

    public function insert(){
        $query = "INSERT INTO admin(admin_name) VALUES('$admin_name')";
        $result = $this->db->myquery($query);
        if($result){
            $msg = "User has been added successfully.";
            return $msg;
        } else {
            $msg = "Error while adding user. Please try again.";
            return $msg;
        }
    }

}

Do this.