# app/models.py

from app import db
from datetime import datetime

class UserModel(db.Model):
    __tablename__ = 'users'

    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), index=True, unique=True)
    email = db.Column(db.String(120), index=True, unique=True)
    password = db.Column(db.String(128), nullable=False)
    registration_date = db.Column(db.DateTime, default=datetime.utcnow)

    def to_dict(self):
        return {
            'user_id': self.id,
            'username': self.username,
            'email': self.email,
            'registration_date': self.registration_date.isoformat() + 'Z'
        }