Add helper functions for Pen

helpers/pen_helpers.py

@@ -0,0 +1,67 @@
+from typing import Optional
+from pydantic import BaseModel, validator
+
+class Pen(BaseModel):
+    name: str
+    color: str
+    brand: str
+    price: int
+    stock: int
+
+    @validator('name')
+    def name_must_not_be_empty(cls, value):
+        if not value.strip():
+            raise ValueError('Name cannot be empty')
+        return value
+
+    @validator('color')
+    def color_must_not_be_empty(cls, value):
+        if not value.strip():
+            raise ValueError('Color cannot be empty')
+        return value
+
+    @validator('brand')
+    def brand_must_not_be_empty(cls, value):
+        if not value.strip():
+            raise ValueError('Brand cannot be empty')
+        return value
+
+    @validator('price')
+    def price_must_be_positive(cls, value):
+        if value <= 0:
+            raise ValueError('Price must be a positive integer')
+        return value
+
+    @validator('stock')
+    def stock_must_be_non_negative(cls, value):
+        if value < 0:
+            raise ValueError('Stock cannot be negative')
+        return value
+
+def create_pen(db, pen_data: Pen):
+    pen = Pen(**pen_data.dict())
+    db.add(pen)
+    db.commit()
+    db.refresh(pen)
+    return pen
+
+def get_pen(db, pen_id: int) -> Optional[Pen]:
+    return db.query(Pen).filter(Pen.id == pen_id).first()
+
+def update_pen(db, pen_id: int, pen_data: Pen):
+    pen = get_pen(db, pen_id)
+    if not pen:
+        return None
+    for field, value in pen_data.dict(exclude_unset=True).items():
+        setattr(pen, field, value)
+    db.commit()
+    db.refresh(pen)
+    return pen
+
+def delete_pen(db, pen_id: int):
+    pen = get_pen(db, pen_id)
+    if not pen:
+        return None
+    db.delete(pen)
+    db.commit()
+    return pen