remove intermediate grocery table and add related_products feature

backend/models.py

@@ -17,6 +17,17 @@ shopping_event_products = Table(
     Column('price', Float, nullable=False)  # Price of this product at the time of this shopping event
 )
 
+# Association table for many-to-many self-referential relationship between related products
+related_products = Table(
+    'related_products',
+    Base.metadata,
+    Column('id', Integer, primary_key=True, autoincrement=True),  # Artificial primary key
+    Column('product_id', Integer, ForeignKey('products.id'), nullable=False),
+    Column('related_product_id', Integer, ForeignKey('products.id'), nullable=False),
+    Column('relationship_type', String, nullable=True),  # Optional: e.g., "size_variant", "brand_variant", "similar"
+    Column('created_at', DateTime(timezone=True), server_default=func.now())
+)
+
 class BrandInShop(Base):
     __tablename__ = "brands_in_shops"
     
@@ -51,27 +62,14 @@ class GroceryCategory(Base):
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
     
     # Relationships
-    groceries = relationship("Grocery", back_populates="category")
-
-class Grocery(Base):
-    __tablename__ = "groceries"
-    
-    id = Column(Integer, primary_key=True, index=True)
-    name = Column(String, nullable=False, index=True)
-    category_id = Column(Integer, ForeignKey("grocery_categories.id"), nullable=False)
-    created_at = Column(DateTime(timezone=True), server_default=func.now())
-    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
-    
-    # Relationships
-    category = relationship("GroceryCategory", back_populates="groceries")
-    products = relationship("Product", back_populates="grocery")
+    products = relationship("Product", back_populates="category")
 
 class Product(Base):
     __tablename__ = "products"
     
     id = Column(Integer, primary_key=True, index=True)
     name = Column(String, nullable=False, index=True)
-    grocery_id = Column(Integer, ForeignKey("groceries.id"), nullable=False)
+    category_id = Column(Integer, ForeignKey("grocery_categories.id"), nullable=False)
     brand_id = Column(Integer, ForeignKey("brands.id"), nullable=True)
     organic = Column(Boolean, default=False)
     weight = Column(Float, nullable=True)  # in grams or kg
@@ -80,9 +78,26 @@ class Product(Base):
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
     
     # Relationships
-    grocery = relationship("Grocery", back_populates="products")
+    category = relationship("GroceryCategory", back_populates="products")
     brand = relationship("Brand", back_populates="products")
     shopping_events = relationship("ShoppingEvent", secondary=shopping_event_products, back_populates="products")
+    
+    # Self-referential many-to-many relationship for related products
+    related_products = relationship(
+        "Product",
+        secondary=related_products,
+        primaryjoin=id == related_products.c.product_id,
+        secondaryjoin=id == related_products.c.related_product_id,
+        back_populates="related_to_products"
+    )
+    
+    related_to_products = relationship(
+        "Product",
+        secondary=related_products,
+        primaryjoin=id == related_products.c.related_product_id,
+        secondaryjoin=id == related_products.c.product_id,
+        back_populates="related_products"
+    )
 
 class Shop(Base):
     __tablename__ = "shops"