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SQLAlchemy Many-to-One relationship and cascade example
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class Image(db.Model): | |
id = db.Column(db.Integer, primary_key=True) | |
url = db.Column(db.String(255)) | |
class ThingWithImage(db.Model): | |
id = db.Column(db.Integer, primary_key=True) | |
image_id = db.Column(db.Integer, db.ForeignKey("image.id")) | |
image = db.relationship("Image", foreign_keys=[image_id]) | |
class ThingWithMultipleImages(db.Model): | |
id = db.Column(db.Integer, primary_key=True) | |
image_id = db.Column(db.Integer, db.ForeignKey("image.id")) | |
logo_id = db.Column(db.Integer, db.ForeignKey("image.id")) | |
image = db.relationship("Image", foreign_keys=[image_id]) | |
logo = db.relationship("Image", foreign_keys=[logo_id]) | |
def delete(self, commit=True): | |
# TODO: Would be nice if unused Image objects could be removed as well | |
if self.image: | |
# This probably fails if some other object has a foreign key pointing to self.image's entry | |
db.session.delete(self.image) | |
if self.logo: | |
# Same problem as with self.image | |
db.session.delete(self.logo) | |
db.session.delete(self) | |
commit and db.session.commit() | |
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