Delete childless parents using SQLAlchemy
I'm grouping Category items under CategoryGroup items and I want to set up a cascading rule to delete all CategoryGroup items for which there are no Category items left.
What is the best way to acheive it with SQLAlchemy?
from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.orm import relationship
from database.connection import Base
class Category(Base):
__tablename__ = 'category'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
category_group_id = Column(Integer, ForeignKey('category_group.id'))
category_group = relationship('CategoryGroup', back_populates='categories')
class CategoryGroup(Base):
__tablename__ = 'category_group'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
categories = relationship('Category', back_populates='category_group')
I tried searching through SQLAlchemy documentation, but couldn't find any scenario suitable for this situation. My best quess is that it should be somehow specified in Category relationship cascade=''.
python sqlalchemy
asked Jan 20 at 9:39
maivelmaivel
1517
add a comment |
I'm grouping Category items under CategoryGroup items and I want to set up a cascading rule to delete all CategoryGroup items for which there are no Category items left.
What is the best way to acheive it with SQLAlchemy?
from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.orm import relationship
from database.connection import Base
class Category(Base):
__tablename__ = 'category'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
category_group_id = Column(Integer, ForeignKey('category_group.id'))
category_group = relationship('CategoryGroup', back_populates='categories')
class CategoryGroup(Base):
__tablename__ = 'category_group'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
categories = relationship('Category', back_populates='category_group')
I tried searching through SQLAlchemy documentation, but couldn't find any scenario suitable for this situation. My best quess is that it should be somehow specified in Category relationship cascade=''.
python sqlalchemy
asked Jan 20 at 9:39
maivelmaivel
1517
This is related. Solution uses an event listener to check the state of the parent’s collections, deleting of empty.
– SuperShoot
Jan 20 at 11:21
add a comment |
I'm grouping Category items under CategoryGroup items and I want to set up a cascading rule to delete all CategoryGroup items for which there are no Category items left.
What is the best way to acheive it with SQLAlchemy?
from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.orm import relationship
from database.connection import Base
class Category(Base):
__tablename__ = 'category'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
category_group_id = Column(Integer, ForeignKey('category_group.id'))
category_group = relationship('CategoryGroup', back_populates='categories')
class CategoryGroup(Base):
__tablename__ = 'category_group'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
categories = relationship('Category', back_populates='category_group')
I tried searching through SQLAlchemy documentation, but couldn't find any scenario suitable for this situation. My best quess is that it should be somehow specified in Category relationship cascade=''.
python sqlalchemy
asked Jan 20 at 9:39
maivelmaivel
1517
I'm grouping Category items under CategoryGroup items and I want to set up a cascading rule to delete all CategoryGroup items for which there are no Category items left.
What is the best way to acheive it with SQLAlchemy?
from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.orm import relationship
from database.connection import Base
class Category(Base):
__tablename__ = 'category'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
category_group_id = Column(Integer, ForeignKey('category_group.id'))
category_group = relationship('CategoryGroup', back_populates='categories')
class CategoryGroup(Base):
__tablename__ = 'category_group'
id = Column(Integer, primary_key=True)
name = Column(String(500), nullable=False)
categories = relationship('Category', back_populates='category_group')
I tried searching through SQLAlchemy documentation, but couldn't find any scenario suitable for this situation. My best quess is that it should be somehow specified in Category relationship cascade=''.
python sqlalchemy
python sqlalchemy
asked Jan 20 at 9:39
maivelmaivel
1517
asked Jan 20 at 9:39
maivelmaivel
1517
asked Jan 20 at 9:39
maivelmaivel
1517
asked Jan 20 at 9:39
maivelmaivel
1517
asked Jan 20 at 9:39
maivelmaivel
1517
1517
This is related. Solution uses an event listener to check the state of the parent’s collections, deleting of empty.
– SuperShoot
Jan 20 at 11:21
add a comment |
This is related. Solution uses an event listener to check the state of the parent’s collections, deleting of empty.
– SuperShoot
Jan 20 at 11:21
This is related. Solution uses an event listener to check the state of the parent’s collections, deleting of empty.
– SuperShoot
Jan 20 at 11:21
This is related. Solution uses an event listener to check the state of the parent’s collections, deleting of empty.
– SuperShoot
Jan 20 at 11:21
add a comment |
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This is related. Solution uses an event listener to check the state of the parent’s collections, deleting of empty.
– SuperShoot
Jan 20 at 11:21