your examples aren't complete or runnable so I don't really know what the issue
is, although having two relationships to the same target class seems a little
unusual and I'm not sure why you'd need that.
On Thu, Dec 17, 2020, at 6:01 PM, maqui...@gmail.com wrote:
>
> I think I may have just found a solution? Not sure if this is correct but it
> looks like it worked when i changed the "extra" relationship to
> passive_deletes=True instead of cascade
>
> class ChildClass(XPressoBase):
> __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", passive_deletes=True)
> On Thursday, December 17, 2020 at 5:50:06 PM UTC-5 maqui...@gmail.com wrote:
>> 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/
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http://www.sqlalchemy.org/
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