Add helper functions for User

helpers/user_helpers.py

@@ -0,0 +1,80 @@
+from typing import Optional
+from pydantic import BaseModel, EmailStr, validator
+from sqlalchemy.orm import Session
+from models import User
+
+class UserCreate(BaseModel):
+    username: str
+    email: EmailStr
+    password: str
+
+    @validator('username')
+    def validate_username(cls, username):
+        if len(username) < 3:
+            raise ValueError('Username must be at least 3 characters long')
+        return username
+
+    @validator('password')
+    def validate_password(cls, password):
+        if len(password) < 8:
+            raise ValueError('Password must be at least 8 characters long')
+        return password
+
+def validate_email(email: str) -> bool:
+    """
+    Validate an email address format.
+    
+    Args:
+        email: The email address to validate
+        
+    Returns:
+        bool: True if email format is valid, False otherwise
+    """
+    pattern = r'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$'
+    return bool(re.match(pattern, email))
+
+def get_user_by_email(db: Session, email: str) -> Optional[User]:
+    """
+    Get a user by their email address.
+    
+    Args:
+        db: Database session
+        email: Email to search for
+        
+    Returns:
+        User object if found, None otherwise
+    """
+    return db.query(User).filter(User.email == email).first()
+
+def create_user(db: Session, user_data: UserCreate) -> User:
+    """
+    Create a new user with validation and error handling.
+    
+    Args:
+        db: Database session
+        user_data: User data for creation
+        
+    Returns:
+        User object if created successfully, raises ValueError otherwise
+    """
+    # Check if email is valid
+    if not validate_email(user_data.email):
+        raise ValueError("Invalid email format")
+    
+    # Check if user already exists
+    existing_user = get_user_by_email(db, user_data.email)
+    if existing_user:
+        raise ValueError("Email already registered")
+    
+    # Create the user
+    db_user = User(
+        username=user_data.username,
+        email=user_data.email,
+        password=user_data.password  # In a real app, hash this password
+    )
+    
+    db.add(db_user)
+    db.commit()
+    db.refresh(db_user)
+    
+    return db_user