public Task UpdateFlashcardById(int flashcardId, double ef, int days)
{
var flashcard = new Flashcard
{
Id = flashcardId,
EasinessFactor = ef,
PreviousDays = days
};
_dbContext.Flashcards.Attach(flashcard);
_dbContext.Entry(flashcard).Property(e => e.EasinessFactor).IsModified = true;
return(_dbContext.SaveChangesAsync());
}
