241 lines
10 KiB
Python
241 lines
10 KiB
Python
from sqlalchemy import Column, Integer, String, Float, Boolean, DateTime, Date, ForeignKey, Table, event, DDL
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from sqlalchemy.ext.declarative import declarative_base
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from sqlalchemy.orm import relationship
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from sqlalchemy.sql import func, text
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from datetime import datetime
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# Constants for temporal tables
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FAR_FUTURE_DATE = "'9999-12-31'"
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Base = declarative_base()
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# Trigger creation SQL
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PRODUCTS_VERSIONING_TRIGGER_SQL = """
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CREATE OR REPLACE FUNCTION products_versioning_trigger()
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RETURNS TRIGGER AS $$
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BEGIN
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-- Handle DELETE operations
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IF TG_OP = 'DELETE' THEN
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-- Create history record for the deleted product
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INSERT INTO products_history (
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id, name, category_id, brand_id, organic, weight, weight_unit,
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created_at, updated_at, valid_from, valid_to, deleted, operation
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) VALUES (
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OLD.id, OLD.name, OLD.category_id, OLD.brand_id, OLD.organic,
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OLD.weight, OLD.weight_unit, OLD.created_at, OLD.updated_at,
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OLD.valid_from, CURRENT_DATE, OLD.deleted, 'D'
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);
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RETURN OLD;
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END IF;
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-- Handle UPDATE operations
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IF TG_OP = 'UPDATE' THEN
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-- Check if any versioned fields have changed
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IF (OLD.name IS DISTINCT FROM NEW.name OR
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OLD.category_id IS DISTINCT FROM NEW.category_id OR
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OLD.brand_id IS DISTINCT FROM NEW.brand_id OR
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OLD.organic IS DISTINCT FROM NEW.organic OR
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OLD.weight IS DISTINCT FROM NEW.weight OR
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OLD.weight_unit IS DISTINCT FROM NEW.weight_unit OR
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OLD.deleted IS DISTINCT FROM NEW.deleted) THEN
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-- Determine the valid_to date for the history record
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DECLARE
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history_valid_to DATE;
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BEGIN
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-- If valid_from was manually changed, use that as the cutoff
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-- Otherwise, use current date for automatic versioning
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IF OLD.valid_from IS DISTINCT FROM NEW.valid_from THEN
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history_valid_to = NEW.valid_from;
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ELSE
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history_valid_to = CURRENT_DATE;
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-- For automatic versioning, update the valid_from to today
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NEW.valid_from = CURRENT_DATE;
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END IF;
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-- Create history record with the old data
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INSERT INTO products_history (
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id, name, category_id, brand_id, organic, weight, weight_unit,
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created_at, updated_at, valid_from, valid_to, deleted, operation
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) VALUES (
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OLD.id, OLD.name, OLD.category_id, OLD.brand_id, OLD.organic,
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OLD.weight, OLD.weight_unit, OLD.created_at, OLD.updated_at,
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OLD.valid_from, history_valid_to, OLD.deleted, 'U'
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);
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END;
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-- Always ensure valid_to is set to far future for current version
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NEW.valid_to = '9999-12-31';
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NEW.updated_at = NOW();
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END IF;
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RETURN NEW;
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END IF;
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RETURN NULL;
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END;
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$$ LANGUAGE plpgsql;
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DROP TRIGGER IF EXISTS products_versioning_trigger ON products;
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CREATE TRIGGER products_versioning_trigger
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BEFORE UPDATE OR DELETE ON products
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FOR EACH ROW
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EXECUTE FUNCTION products_versioning_trigger();
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"""
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# Association table for many-to-many relationship between shopping events and products
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shopping_event_products = Table(
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'shopping_event_products',
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Base.metadata,
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Column('id', Integer, primary_key=True, autoincrement=True), # Artificial primary key
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Column('shopping_event_id', Integer, ForeignKey('shopping_events.id'), nullable=False),
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Column('product_id', Integer, ForeignKey('products.id'), nullable=False),
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Column('amount', Float, nullable=False), # Amount of this product bought in this event
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Column('price', Float, nullable=False), # Price of this product at the time of this shopping event
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Column('discount', Boolean, default=False, nullable=False) # Whether this product was purchased with a discount
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)
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# Association table for many-to-many self-referential relationship between related products
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related_products = Table(
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'related_products',
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Base.metadata,
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Column('id', Integer, primary_key=True, autoincrement=True), # Artificial primary key
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Column('product_id', Integer, ForeignKey('products.id'), nullable=False),
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Column('related_product_id', Integer, ForeignKey('products.id'), nullable=False),
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Column('relationship_type', String, nullable=True), # Optional: e.g., "size_variant", "brand_variant", "similar"
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Column('created_at', DateTime(timezone=True), server_default=func.now())
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)
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class BrandInShop(Base):
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__tablename__ = "brands_in_shops"
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id = Column(Integer, primary_key=True, index=True)
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shop_id = Column(Integer, ForeignKey("shops.id"), nullable=False)
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brand_id = Column(Integer, ForeignKey("brands.id"), nullable=False)
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created_at = Column(DateTime(timezone=True), server_default=func.now())
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updated_at = Column(DateTime(timezone=True), onupdate=func.now())
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# Relationships
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shop = relationship("Shop", back_populates="brands_in_shop")
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brand = relationship("Brand", back_populates="shops_with_brand")
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class Brand(Base):
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__tablename__ = "brands"
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id = Column(Integer, primary_key=True, index=True)
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name = Column(String, nullable=False, index=True)
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created_at = Column(DateTime(timezone=True), server_default=func.now())
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updated_at = Column(DateTime(timezone=True), onupdate=func.now())
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# Relationships
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products = relationship("Product", back_populates="brand")
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shops_with_brand = relationship("BrandInShop", back_populates="brand")
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class GroceryCategory(Base):
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__tablename__ = "grocery_categories"
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id = Column(Integer, primary_key=True, index=True)
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name = Column(String, nullable=False, index=True)
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created_at = Column(DateTime(timezone=True), server_default=func.now())
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updated_at = Column(DateTime(timezone=True), onupdate=func.now())
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# Relationships
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products = relationship("Product", back_populates="category")
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class Product(Base):
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__tablename__ = "products"
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id = Column(Integer, primary_key=True, index=True)
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name = Column(String, nullable=False, index=True)
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category_id = Column(Integer, ForeignKey("grocery_categories.id"), nullable=False)
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brand_id = Column(Integer, ForeignKey("brands.id"), nullable=True)
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organic = Column(Boolean, default=False)
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weight = Column(Float, nullable=True) # in grams or kg
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weight_unit = Column(String, default="piece") # "g", "kg", "ml", "l", "piece"
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created_at = Column(DateTime(timezone=True), server_default=func.now())
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updated_at = Column(DateTime(timezone=True), onupdate=func.now())
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# Temporal columns for versioning
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valid_from = Column(Date, server_default=func.current_date(), nullable=False)
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valid_to = Column(Date, server_default=text(FAR_FUTURE_DATE), nullable=False)
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deleted = Column(Boolean, default=False, nullable=False)
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# Relationships
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category = relationship("GroceryCategory", back_populates="products")
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brand = relationship("Brand", back_populates="products")
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shopping_events = relationship("ShoppingEvent", secondary=shopping_event_products, back_populates="products")
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# Self-referential many-to-many relationship for related products
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# We'll use a simpler approach without back_populates to avoid circular references
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related_products = relationship(
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"Product",
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secondary=related_products,
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primaryjoin="Product.id == related_products.c.product_id",
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secondaryjoin="Product.id == related_products.c.related_product_id",
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viewonly=True
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)
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class ProductHistory(Base):
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__tablename__ = "products_history"
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history_id = Column(Integer, primary_key=True, index=True)
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id = Column(Integer, nullable=False, index=True) # Original product ID
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name = Column(String, nullable=False)
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category_id = Column(Integer, nullable=False)
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brand_id = Column(Integer, nullable=True)
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organic = Column(Boolean, default=False)
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weight = Column(Float, nullable=True)
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weight_unit = Column(String, default="piece")
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created_at = Column(DateTime(timezone=True))
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updated_at = Column(DateTime(timezone=True))
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# Temporal columns
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valid_from = Column(Date, nullable=False)
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valid_to = Column(Date, nullable=False)
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deleted = Column(Boolean, default=False, nullable=False)
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# Audit columns
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operation = Column(String(1), nullable=False) # 'U' for Update, 'D' for Delete
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archived_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)
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# Create trigger after ALL tables are created
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@event.listens_for(Base.metadata, 'after_create')
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def create_products_versioning_trigger_after_all_tables(target, connection, **kw):
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"""Create the products versioning trigger after all tables are created"""
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try:
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connection.execute(text(PRODUCTS_VERSIONING_TRIGGER_SQL))
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print("✅ Products versioning trigger created successfully")
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except Exception as e:
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print(f"⚠️ Warning: Could not create products versioning trigger: {e}")
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# Don't fail the entire application startup if trigger creation fails
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pass
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class Shop(Base):
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__tablename__ = "shops"
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id = Column(Integer, primary_key=True, index=True)
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name = Column(String, nullable=False, index=True)
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city = Column(String, nullable=False)
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address = Column(String, nullable=True)
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created_at = Column(DateTime(timezone=True), server_default=func.now())
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updated_at = Column(DateTime(timezone=True), onupdate=func.now())
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# Relationships
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shopping_events = relationship("ShoppingEvent", back_populates="shop")
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brands_in_shop = relationship("BrandInShop", back_populates="shop")
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class ShoppingEvent(Base):
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__tablename__ = "shopping_events"
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id = Column(Integer, primary_key=True, index=True)
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shop_id = Column(Integer, ForeignKey("shops.id"), nullable=False)
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date = Column(DateTime(timezone=True), nullable=False, default=datetime.utcnow)
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total_amount = Column(Float, nullable=True) # Total cost of the shopping event
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notes = Column(String, nullable=True)
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created_at = Column(DateTime(timezone=True), server_default=func.now())
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updated_at = Column(DateTime(timezone=True), onupdate=func.now())
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# Relationships
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shop = relationship("Shop", back_populates="shopping_events")
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products = relationship("Product", secondary=shopping_event_products, back_populates="shopping_events") |