Add Api for create review

app/controller/book/BookDb.php

@@ -45,6 +45,21 @@
 
             return $books;
         }
+
+        function updateRating($book_id, $rating, $banyak_review) {
+            $books = $this->getBookById($book_id);
+            $now_rating = $books[0]->rating;
+            $new_rating = ((float)($now_rating * $banyak_review + $rating) / (float)($banyak_review + 1));
+
+            $book = null;
+            $sql = "UPDATE book SET rating = ? where book_id = ?";
+            $stmt = $this->conn->prepare($sql);
+            if ($stmt->execute([$new_rating, $book_id])) {
+                $book = new Book($book_id, null, null, null, $new_rating);
+            }
+
+            return $book;
+        }
     }
 
 ?>
\ No newline at end of file