for (flashcard in flashcards) {
    let word = flashcard.word || '';
    let image = flashcard.image || '';
    let pronunciation = flashcard.pronunciation || '';
    let meaning = flashcard.meaning || '';
    let order = flashcard.order || -1; // -1 is unordered
    let remember_score = 0;
    FlashcardModel.createFlashcard(word, pronunciation, meaning, image, order, remember_score, req.body.collection_id);
}