da

    $app->get('/category', function (Request $request, Response $response, array $args) {
        $sth = $this->db->prepare("SELECT * FROM category");
        $sth->execute();
        $categories = $sth->fetchAll();
        return $this->response->withJson($categories);
    });

    $app->get('/category/[{category_id}]', function (Request $request, Response $response, array $args) {
        $sth = $this->db->prepare("SELECT category_id, name
            FROM category WHERE category_id=:category_id");
        $sth->bindParam("category_id", $args['category_id']);
        $sth->execute();
        $books = $sth->fetch();

        return $this->response->withJson($books);
    });


    $app->post('/category', function (Request $request, Response $response) {
        $input = $request->getParsedBody();
        if (!$input['name']) {
            return $this->response->withStatus(400)->withJson(array("message" => "Data incomplete."));
        }

        $sql = "INSERT INTO category (name) VALUES (:name)";
        $sth = $this->db->prepare($sql);
        $sth->bindParam("name", $input['name']);
        $sth->execute();
        return $this->response->withStatus(201)->withJson(array("message" => "Category was created."));
    });

    $app->delete('/category/[{category_id}]', function (Request $request, Response $response, array $args) {
        $sth = $this->db->prepare("DELETE FROM category WHERE category_id=:category_id");
        $sth->bindParam("category_id", $args['category_id']);
        $sth->execute();

        $count = $sth->rowCount();
        if ($count != 1) {
            return $this->response->withStatus(404)->withJson(array("message" => "Could not execute statement. Category not found"));
        }
        return $this->response->withJson(array("message" => "Category was deleted."));
    });

    $app->put('/category/[{category_id}]', function (Request $request, Response $response, array $args) {
        $input = $request->getParsedBody();
        if (!$input['name']) {
            return $this->response->withStatus(400)->withJson(array("message" => "Could not execute statement. Data incomplete."));
        }

        $sql = "UPDATE category SET name=:name WHERE category_id=:category_id";
        $sth = $this->db->prepare($sql);
        $sth->bindParam("category_id", $args['category_id']);
        $sth->bindParam("name", $input['name']);
        $sth->execute();

        $count = $sth->rowCount();
        if ($count != 1) {
            return $this->response->withStatus(404)->withJson(array("message" => "Could not execute statement. Category not found"));
        }
        return $this->response->withJson(array("message" => "Category was updated."));
    });