models.py

from flask_sqlalchemy import SQLAlchemy
from werkzeug.security import generate_password_hash, check_password_hash

db = SQLAlchemy()

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(100), unique=True, nullable=False)
    password_hash = db.Column(db.String(200), nullable=False)
    expenses = db.relationship('Expense', backref='user', lazy=True)

    def set_password(self, password):
        """Hashes the password before storing it"""
        self.password_hash = generate_password_hash(password)

    def check_password(self, password):
        """Checks if the entered password matches the stored hash"""
        return check_password_hash(self.password_hash, password)

class Expense(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(100), nullable=False)
    category = db.Column(db.String(50), nullable=False)
    amount = db.Column(db.Float, nullable=False)
    date = db.Column(db.Date, nullable=False)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)  # Ensures expenses are linked to users