Hello! I am working with the *Composite Association Proxies* example available under the following link:
https://docs.sqlalchemy.org/en/latest/orm/extensions/associationproxy.html#composite-association-proxies *My problem: *when I delete the keys of the dictionary, SQLAlchemy let the values of the dictionary in the database. The keys are deleted, but not the values. I didn't modify the functioning of the Composite Association Proxies example. I just created and stored an "User" object before trying to delete the keys from the dictionary. *Here is the code:* from sqlalchemy import Column, Integer, String, ForeignKey, create_engine from sqlalchemy.orm import relationship, backref, Session from sqlalchemy.ext.associationproxy import association_proxy from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.orm.collections import attribute_mapped_collection engine = create_engine('sqlite:///foo.db') Base = declarative_base() class User(Base): __tablename__ = 'user' id = Column(Integer, primary_key=True) name = Column(String(64)) # the same 'user_keywords'->'keyword' proxy as in # the basic dictionary example keywords = association_proxy( 'user_keywords', 'keyword', creator=lambda k, v: UserKeyword(special_key=k, keyword=v) ) def __init__(self, name): self.name = name class UserKeyword(Base): __tablename__ = 'user_keyword' user_id = Column(Integer, ForeignKey('user.id'), primary_key=True) keyword_id = Column(Integer, ForeignKey('keyword.id'), primary_key=True) special_key = Column(String) user = relationship(User, backref=backref( "user_keywords", collection_class=attribute_mapped_collection("special_key"), cascade="all, delete-orphan" ) ) # the relationship to Keyword is now called # 'kw' kw = relationship("Keyword") # 'keyword' is changed to be a proxy to the # 'keyword' attribute of 'Keyword' keyword = association_proxy('kw', 'keyword') class Keyword(Base): __tablename__ = 'keyword' id = Column(Integer, primary_key=True) keyword = Column('keyword', String(64)) def __init__(self, keyword): self.keyword = keyword Base.metadata.create_all(engine) session = Session(engine) john = User("john") session.add(john) john.keywords["k1"] = "v1" john.keywords["k2"] = "v2" session.commit() del john.keywords["k2"] del john.keywords["k1"] session.commit() *Here are the values stored in the database after the two commits:* *Table USER:* ID - NAME 1 - "john" *Table USER_KEYWORD:* USER_ID - KEYWORD_ID - SPECIAL_KEY The table is empty. *Table KEYWORD:* ID - KEYWORD 1 - "v1" 2 - "v2" Is it possible to configure SQLAlchemy in order to also delete the values of the dictionary from the database when the keys are deleted? I don't know if it can explains something but I am using PostgreSQL. Thank you for your help! Sven -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
