examples.dogpile_caching.model
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2023-12-01
"""The datamodel, which represents Person that has multiple Address objects, each with PostalCode, City, Country. Person --(1..n)--> Address Address --(has a)--> PostalCode PostalCode --(has a)--> City City --(has a)--> Country """ from sqlalchemy import Column from sqlalchemy import ForeignKey from sqlalchemy import Integer from sqlalchemy import String from sqlalchemy.orm import relationship from .caching_query import RelationshipCache from .environment import Base from .environment import bootstrap class Country(Base): __tablename__ = "country" id = Column(Integer, primary_key=True) name = Column(String(100), nullable=False) def __init__(self, name): self.name = name class City(Base): __tablename__ = "city" id = Column(Integer, primary_key=True) name = Column(String(100), nullable=False) country_id = Column(Integer, ForeignKey("country.id"), nullable=False) country = relationship(Country) def __init__(self, name, country): self.name = name self.country = country class PostalCode(Base): __tablename__ = "postal_code" id = Column(Integer, primary_key=True) code = Column(String(10), nullable=False) city_id = Column(Integer, ForeignKey("city.id"), nullable=False) city = relationship(City) @property def country(self): return self.city.country def __init__(self, code, city): self.code = code self.city = city class Address(Base): __tablename__ = "address" id = Column(Integer, primary_key=True) person_id = Column(Integer, ForeignKey("person.id"), nullable=False) street = Column(String(200), nullable=False) postal_code_id = Column(Integer, ForeignKey("postal_code.id")) postal_code = relationship(PostalCode) @property def city(self): return self.postal_code.city @property def country(self): return self.postal_code.country def __str__(self): return "%s\t%s, %s\t%s" % ( self.street, self.city.name, self.postal_code.code, self.country.name, ) class Person(Base): __tablename__ = "person" id = Column(Integer, primary_key=True) name = Column(String(100), nullable=False) addresses = relationship(Address, collection_class=set) def __init__(self, name, *addresses): self.name = name self.addresses = set(addresses) def __str__(self): return self.name def __repr__(self): return "Person(name=%r)" % self.name def format_full(self): return "\t".join([str(x) for x in [self] + list(self.addresses)]) # Caching options. A set of three RelationshipCache options # which can be applied to Query(), causing the "lazy load" # of these attributes to be loaded from cache. cache_address_bits = ( RelationshipCache(PostalCode.city, "default") .and_(RelationshipCache(City.country, "default")) .and_(RelationshipCache(Address.postal_code, "default")) ) bootstrap()