So I have a few tables as follows (abbreviated for unnecessary columns):
class Project(Base):
__tablename__ = 'projects'
id = Column(u'project_id', INTEGER(), primary_key=True)
applications = relationship(
'AppDefinition',
secondary=lambda: Base.metadata.tables['project_package'],
passive_deletes=True,
lazy=False,
)
package_definitions = relationship(
'PackageDefinition',
secondary=lambda: Base.metadata.tables['project_package'],
passive_deletes=True,
)
class PackageDefinition(Base):
__tablename__ = 'package_definitions'
id = Column(u'pkg_def_id', INTEGER(), primary_key=True)
applications = relationship(
'AppDefinition',
secondary=lambda: Base.metadata.tables['project_package'],
passive_deletes=True,
)
projects = relationship(
'Project',
secondary=lambda: Base.metadata.tables['project_package'],
passive_deletes=True,
)
class AppDefinition(Base):
__tablename__ = 'app_definitions'
id = Column(u'AppID', SMALLINT(display_width=2), primary_key=True)
package_definitions = relationship(
'PackageDefinition',
secondary=lambda: Base.metadata.tables['project_package'],
passive_deletes=True,
)
projects = relationship(
'Project',
secondary=lambda: Base.metadata.tables['project_package'],
passive_deletes=True,
)
class ProjectPackage(Base):
__tablename__ = 'project_package'
project_id = Column(
INTEGER(),
ForeignKey('projects.project_id', ondelete='cascade'),
primary_key=True
)
pkg_def_id = Column(
INTEGER(),
ForeignKey('package_definitions.pkg_def_id', ondelete='cascade'),
primary_key=True
)
app_id = Column(
SMALLINT(display_width=6),
ForeignKey('app_definitions.AppID', ondelete='cascade'),
primary_key=True
)
app_definition = relationship('AppDefinition', uselist=False)
package_definition = relationship('PackageDefinition', uselist=False)
project = relationship('Project', uselist=False)
If I select a row from the projects table and try to delete it, when I try
to commit
the session I get something like this:
[INFO] DELETE FROM project_package WHERE project_package.project_id = ? AND
project_package.app_id = ?
[INFO] (1L, 1L)
[INFO] DELETE FROM project_package WHERE project_package.project_id = ? AND
project_package.pkg_def_id = ?
[INFO] (1L, 1L)
[INFO] ROLLBACK
At the time of the delete, the project_package table simply has this:
[('project_id', 1L), ('pkg_def_id', 1L), ('app_id', 1L)]
Obviously the combination of the "ondelete='cascade'" settings in the
project_package table and the 'passive_deletes' settings in the
relationships
is what's triggering this, but after try many different searches on Google,
I'm
not finding the right solution to fix this; obviously I only want it to
attempt to
delete the row once, but each relationship in project is triggering its own
delete which is "bad".
So... help? Am I missing something simple here, or is my model not good
enough to do the right thing?
--
- Ken Lareau
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