Category.php (Model)

<?php

class Category {

    // database connection and table name
    private $conn;
    private $table_name = "kategori";

    // object properties
    public $ID;
    public $katNavn;

    // constructor with $db as database connection
    public function __construct($db) {
        $this->conn = $db;
    }

    // read products
    function read($id) {
        $query = "SELECT * FROM " . $this->table_name;

        if($id != '-1') {
            // select query
            $query .= " WHERE kategori.ID = ".$id;
        }
        // prepare query statement
        $stmt = $this->conn->prepare($query);

        // execute query
        $stmt->execute();

        return $stmt;
    }

    function write($post) {
        $katNavn = $post['katNavn'];
        $query = "INSERT INTO " . $this->table_name . " (katNavn) VALUES " .
        "('$katNavn');";

        // prepare query statement
        $stmt = $this->conn->prepare($query);

        try {
            // execute query
            return $stmt->execute();
        } catch (PDOException $e) {
            return ($e);
        }

    }

    function update($post) {
        $katNavn = $post['katNavn'];
        $id = $post['ID'];
        $query = "UPDATE " . $this->table_name . " SET katNavn = '". $katNavn ."' WHERE ID = '" .$id."'";

        $stmt = $this->conn->prepare($query);

        if(!$stmt) return $this->conn->errorInfo();

        return $stmt->execute();
    }

    function delete($id) {
        $query = "DELETE FROM " . $this->table_name . " WHERE ID = ".$id;

        $stmt = $this->conn->prepare($query);

        return $stmt->execute();
    }
}