foreach ($categoriesBD->getAllCategories() as $cat) {
                if ($cat->getName() == $_POST['nom']) {
                    header('Location: ../addCategory.php');
                }
            }
            $category = new Category(-1, $_POST['nom'], 0);
            print_r($category);
            $_SESSION["ajout"] = $categoriesBD->addCategory($category);
            print_r($_SESSION["ajout"]);
        }
        header('Location: ../addCategory.php');
    } else {
        if (isset($_POST['edit'])) {
            $_SESSION["edit"] = false;
            if (isset($_POST)) {
                $category = $categoriesBD->getCategory($_POST['id']);
                $category->setName(isset($_POST['nom']) ? $_POST['nom'] : $category->getName());
                $_SESSION["edit"] = $categoriesBD->updateCategory($category);
                header('Location: ../editCategory.php?id=' . $category->getId());
            }
        } else {
            if (isset($_POST['deleteCategory'])) {
                $_SESSION["delete"] = false;
                if (isset($_POST)) {
                    $_SESSION["delete"] = $categoriesBD->deleteCategory($_POST['id']);
                    header('Location: ../admin.php');
                }
            }
        }
    }
}
<?php

include_once "includes/include.php";
$categories = new CategoriesBD();
if (isset($_GET['id'])) {
    $mycategory = $categories->getCategory($_GET['id']);
    if ($mycategory == null) {
        header('Location: index.php');
    }
} else {
    header('Location: index.php');
}
?>

<!doctype html>
<html>
    <head>
        <?php 
include_once "includes/head.php";
?>
        <title>My Movie Static</title>    
    </head>
    <body>
        <?php 
include_once "includes/navbar.php";
if (isset($_SESSION["edit"]) && $_SESSION["edit"] == true) {
    showModal("Edition complète", "L'édition a été réalisée avec succès.");
} else {
    if (isset($_SESSION["edit"]) && $_SESSION["edit"] == false) {
        showModal("Edition ratée", "L'édition n'a pas pu aboutir.");
    }
echo "<span class=\"glyphicon glyphicon-star\"></span>";
echo "<span class=\"glyphicon glyphicon-star\"></span>";
echo "<span class=\"glyphicon glyphicon-star\"></span>";
echo "<span class=\"glyphicon glyphicon-star\"></span>";
echo "</button>";
echo "</li>";
echo "</form>";
echo "</ul>";
echo "</div>";
echo "<h3>" . escape($mymovie->getDirector()) . ", " . escape($mymovie->getYear()) . "</h3>";
// Réalisateur & Année
echo "<p>" . escape($mymovie->getDescriptionLong()) . "</p>";
// Descripton
echo "<div class=\"categorySize\">";
echo "<span class=\"label label-success \">";
echo "<span class=\"glyphicon glyphicon-tag\"></span> " . escape($categoriesBD->getCategory($mymovie->getCategory())->getName());
// Catégorie
echo "</span>";
echo "</div>";
echo "<br>";
if ($_SESSION["utilisateur"]->getId() != $mymovie->getUser()) {
    $etat = "disabled";
    $hrefedit = "#";
} else {
    $etat = "activated";
    $hrefedit = "edit.php?id=" . $mymovie->getId();
}
// Bouton édition
echo "<a role=\"button\" class=\"btn btn-primary btn-lg\" href=\"" . $hrefedit . "\" " . $etat . ">";
echo "<span class=\"glyphicon glyphicon-edit\" aria-hidden=\"true\"></span> Editer";
echo "</a> ";