Add helper functions for Pen

helpers/pen_helpers.py

@@ -0,0 +1,115 @@
+from typing import List, Dict, Optional, Union, Any
+from sqlalchemy.orm import Session
+from models.pen import Pen
+from schemas.pen import PenCreate, PenUpdate
+from decimal import Decimal
+
+def validate_pen_price(price: int) -> bool:
+    """
+    Validate that pen price is within acceptable range.
+    
+    Args:
+        price: The pen price to validate
+        
+    Returns:
+        bool: True if price is valid, False otherwise
+    """
+    return price > 0 and price < 100000
+
+def validate_pen_color(color: str) -> bool:
+    """
+    Validate that pen color is an acceptable value.
+    
+    Args:
+        color: The pen color to validate
+        
+    Returns: 
+        bool: True if color is valid, False otherwise
+    """
+    valid_colors = ['black', 'blue', 'red', 'green', 'purple']
+    return color.lower() in valid_colors
+
+def get_pen_by_name_and_brand(db: Session, name: str, brand: str) -> Optional[Pen]:
+    """
+    Get a pen by name and brand combination.
+    
+    Args:
+        db: Database session
+        name: Pen name
+        brand: Pen brand
+        
+    Returns:
+        Pen object if found, None otherwise
+    """
+    return db.query(Pen).filter(Pen.name == name, Pen.brand == brand).first()
+
+def create_pen_safely(db: Session, pen_data: PenCreate) -> Union[Pen, Dict[str, str]]:
+    """
+    Create a new pen with validation and error handling.
+    
+    Args:
+        db: Database session
+        pen_data: Pen data for creation
+        
+    Returns:
+        Pen object if created successfully, error dict otherwise
+    """
+    if not validate_pen_price(pen_data.price):
+        return {"error": "Invalid price range"}
+        
+    if not validate_pen_color(pen_data.color):
+        return {"error": "Invalid pen color"}
+    
+    existing_pen = get_pen_by_name_and_brand(db, pen_data.name, pen_data.brand)
+    if existing_pen:
+        return {"error": "Pen with this name and brand already exists"}
+    
+    db_pen = Pen(
+        name=pen_data.name,
+        brand=pen_data.brand,
+        color=pen_data.color.lower(),
+        price=pen_data.price,
+        in_stock=True,
+        description=pen_data.description
+    )
+    
+    db.add(db_pen)
+    db.commit()
+    db.refresh(db_pen)
+    
+    return db_pen
+
+def update_pen_stock(db: Session, pen_id: int, in_stock: bool) -> Union[Pen, Dict[str, str]]:
+    """
+    Update the stock status of a pen.
+    
+    Args:
+        db: Database session
+        pen_id: ID of pen to update
+        in_stock: New stock status
+        
+    Returns:
+        Updated pen object if successful, error dict otherwise
+    """
+    pen = db.query(Pen).filter(Pen.id == pen_id).first()
+    if not pen:
+        return {"error": "Pen not found"}
+        
+    pen.in_stock = in_stock
+    db.commit()
+    db.refresh(pen)
+    
+    return pen
+
+def get_pens_by_brand(db: Session, brand: str) -> List[Pen]:
+    """
+    Get all pens from a specific brand.
+    
+    Args:
+        db: Database session
+        brand: Brand name to filter by
+        
+    Returns:
+        List of pen objects for the brand
+    """
+    return db.query(Pen).filter(Pen.brand == brand).all()