I have a polymorphic data model where association tables are to base classes and some relationships that link to different child classes to filter out the non-matching base classes, however these seem to result in sqlalchemy being unable to delete cascade properly
In a real case lets say i have class Base(): children = relationship("Base", secondary="mix_base_base", cascade="all, delete") someTypes = relationship("SomeType", secondary="mix_base_base", cascade="all, delete") other_types = relationship("OtherType", secondary="mix_base_base", cascade="all") class SomeType(Base): parents = relationship("Base", secondary="mix_base_base", passive_deletes=True) class OtherType(Base): parents = relationship("Base", secondary="mix_base_base", passive_deletes=True) if I delete a base that doesn't have relationships to SomeType and OtherType, then everything works great. However once I add those extra relationships sqlalchemy no longer deletes the children relationships. This can be overcome by using lazy="dynamic" on the relationships, but at GREAT performance cost (about 100%), which isn't good. Does anyone know how to get around this without using dynamic loading? The specific relationships are important for front end pagination of data, but the performance cost is too great for the amount of data in this system to double the query times. a simplified and stupid workable example where I just add a redundant children2 relationship to ChildClass, resulting in the same problem: from uuid import uuid4 from sqlalchemy import Column from sqlalchemy.dialects.postgresql.base import UUID from sqlalchemy.orm import relationship from webapp.database.orm.base import XPressoBase class ChildClass(Base): __tablename__ = "child_class" id = Column("id", UUID(as_uuid=True), primary_key=True, default=uuid4()) parents = relationship("ParentClass", secondary="mix_parent_class_child_class", passive_deletes=True) children = relationship("ChildChildClass", secondary="mix_child_class_child_child_class", cascade="all, delete") children2 = relationship("ChildChildClass", secondary="mix_child_class_child_child_class", cascade="all, delete") class ChildChildClass(Base): __tablename__ = "child_child_class" id = Column("id", UUID(as_uuid=True), primary_key=True, default=uuid4()) parents = relationship("ChildClass", secondary="mix_child_class_child_child_class", passive_deletes=True) class ParentClass(Base): __tablename__ = "parent_class" id = Column("id", UUID(as_uuid=True), primary_key=True, default=uuid4()) children = relationship("ChildClass", secondary="mix_parent_class_child_class", cascade="all, delete") from sqlalchemy.sql.schema import Table, ForeignKey, Column, UniqueConstraint from webapp.database.orm.base import XPressoBase mix_parent_class_child_class = Table( "mix_parent_class_child_class", XPressoBase.metadata, Column("parent_class_id", ForeignKey("parent_class.id", ondelete="CASCADE"), nullable=False), Column("child_class_id", ForeignKey("child_class.id"), nullable=False), UniqueConstraint( "parent_class_id", "child_class_id", name="uix_parent_class_child_class" ), ) mix_child_class_child_child_class = Table( "mix_child_class_child_child_class", XPressoBase.metadata, Column("child_class_id", ForeignKey("child_class.id", ondelete="CASCADE"), nullable=False), Column("child_child_class_id", ForeignKey("child_child_class.id"), nullable=False), UniqueConstraint( "child_class_id", "child_child_class_id", name="uix_child_class_child_child_class" ), ) -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/e6546493-673c-4aab-aa96-88984c1a2e1en%40googlegroups.com.