Add UserRole model with 1:1 relationship to User

[Copilot]

Implements role-based access control foundation by adding a UserRole model with a 1:1 relationship to User. The problem statement showed a type mismatch (db.Integer foreign key against db.String(36) primary key) which would fail at runtime.

Changes

• Created UserRole model following the UserStats pattern:

  • Uses db.String(36) for primary key and foreign key (matches User.id UUID type)
  • Defaults to "User" role
  • Cascade deletes with parent User

• Updated User model:

  • Added role relationship with uselist=False for 1:1 semantics

• Added test coverage for creation, relationship bidirectionality, cascade delete, defaults, and type validation

Implementation

class UserRole(db.Model):
    __tablename__ = "user_roles"
    
    id = db.Column(
        db.String(36), db.ForeignKey("users.id", ondelete="CASCADE"), primary_key=True
    )
    role = db.Column(db.String(50), default="User", nullable=False)
    created_at = db.Column(db.DateTime, server_default=db.func.now(), nullable=False)

class User(db.Model):
    # ...
    role = db.relationship(
        "UserRole", backref="user", uselist=False, cascade="all, delete-orphan"
    )

Access pattern: user.role.role returns the role string; user_role.user returns the User instance.

Original prompt

class User(db.Model):
"""
User model for the application. Stores user information such as email, password, and username.

Attributes:
    id (str): Unique identifier for the user.
    email (str): Email address of the user.
    password (str): Hashed password of the user.
    username (str): Username of the user.
    created_at (datetime): Timestamp when the user was created.
    updated_at (datetime): Timestamp when the user was last updated.

Relationships:
    stats (UserStats): One-to-one relationship with UserStats.
"""

__tablename__ = "users"

id = db.Column(db.String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
email = db.Column(db.String(120), unique=True, nullable=False)
username = db.Column(db.String(120), unique=True, nullable=False)
password = db.Column(db.String(256), nullable=False)
created_at = db.Column(db.DateTime, server_default=db.func.now())
updated_at = db.Column(
    db.DateTime, server_default=db.func.now(), onupdate=db.func.now()
)

# ------------
# User relationships
# ------------
stats = db.relationship(
    "UserStats", backref="user", uselist=False, cascade="all, delete-orphan"
)

class UserRole(db.Model):
tablename = "user_roles"

user_id = db.Column(db.Integer, db.ForeignKey("users.id"), nullable=False)
role = db.Column(db.String(50), nullable=False)
created_at = db.Column(db.DateTime, default=db.func.current_timestamp())

How to properly create a relation between the User and UserRole models, That is related to issue #22

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