from datetime import datetime

class Diary:
    def __init__(self, content, keywords):
        self.content = content
        self.keywords = keywords
        self.created_at = datetime.now()
        
    def to_dict(self):
        return {
            'content': self.content,
            'keywords': self.keywords,
            'created_at': self.created_at.isoformat()
        }