if GTDataSetVersion -> GTDataSetImages is one to many, then GTDataSetImages needs to have a foreign key to the primary key of GTDataSetVersion. GTDataSetVersion.gtdatasetid is only part of its primary key and is not unique. you need a composite foriegn key to GTDataSetVersion(version, gtdataset_id). Composite foreign keys must use the ForeignKeyConstraint class are illustrated at https://docs.sqlalchemy.org/en/13/core/constraints.html#defining-foreign-keys . For background on how to use these with declarative mappings see https://docs.sqlalchemy.org/en/13/orm/extensions/declarative/table_config.html#table-configuration .
On Sat, Oct 5, 2019, at 7:09 AM, Nitin Jain wrote: > Hi all, > > In my DB model (We can have multiple GTdatasets where each dataset can have > multiple versions where each version in-turn can have multiple images ) we > have multiple foreign keys (version and id ) in gtdataset images table > referencing to the version table.In version table , only version is not > unique but combination of datsetid and version is unique . How can we define > such relationships. I am really struggling to find the solution. If someone > has faced this kind of problem , it will be helpful. > > `class GTDataSet(db.Model):` > `__tablename__ = 'gtdataset' id = db.Column(db.Integer, primary_key=True, autoincrement=True) gtdatasetid = db.Column(db.String(50), primary_key=True,unique=True) gtdataset_category = db.Column(db.String(50)) gtdataset_name = db.Column(db.Text) gtdatasetversion = db.relationship('GTDataSetVersion', backref='gtdataset',lazy='joined')` > > `class GTDataSetVersion(db.Model):` > `__tablename__ = 'gtdataset_version' version = db.Column(db.String(5), primary_key=True) gtdatasetid = db.Column(db.String(50), db.ForeignKey('gtdataset.gtdatasetid',ondelete='CASCADE'),primary_key=True) register_user = db.Column(db.String(50)) register_date = db.Column(db.DateTime) last_update_user = db.Column(db.String(50)) last_update_date = db.Column(db.DateTime) images = db.relationship('GTDataSetImages', backref='gtdataset_version',lazy='joined', \ primaryjoin = "GTDataSetVersion.version==GTDataSetImages.version")` > > `class GTDataSetImages(SoftDeletionModel):` > `__tablename__ = 'gtdataset_images' id = db.Column(db.Integer, primary_key=True, autoincrement=True) image_id = db.Column(db.String(50), db.ForeignKey('images.image_id'), primary_key=True) register_user = db.Column(db.String(50)) register_date = db.Column(db.DateTime) image = db.relationship('Images', backref='gtdataset_images', lazy='joined') version = db.Column(db.String(5), db.ForeignKey('gtdataset_version.version'), primary_key=True) gtdatasetversion = db.relationship('GTDataSetVersion', foreign_keys=[version], backref='version_gtdataset_images', lazy='joined') gtid = db.Column(db.String(50), db.ForeignKey('gtdataset_version.gtdatasetid'), primary_key=True) gtdataid = db.relationship('GTDataSetVersion', foreign_keys=[gtid], backref='id_gtdataset_images', lazy='joined')` > > Error :- > > sqlalchemy.exc.ProgrammingError: (psycopg2.errors.InvalidForeignKey) there is > no unique constraint matching given keys for referenced table > "gtdataset_version" > [SQL: CREATE TABLE gtdataset_images ( deleted_at TIMESTAMP WITH TIME ZONE, id > SERIAL NOT NULL, image_id VARCHAR(50) NOT NULL, register_user VARCHAR(50), > register_date TIMESTAMP WITHOUT TIME ZONE, version VARCHAR(5) NOT NULL, gtid > VARCHAR(50) NOT NULL, PRIMARY KEY (id, image_id, version, gtid), FOREIGN > KEY(image_id) REFERENCES images (image_id), FOREIGN KEY(version) REFERENCES > gtdataset_version (version), FOREIGN KEY(gtid) REFERENCES gtdataset_version > (gtdatasetid) ) > ] (Background on this error at: http://sqlalche.me/e/f405) > > -- > 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/c2a0b20c-fef3-4825-b23b-5b863f187a91%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/c2a0b20c-fef3-4825-b23b-5b863f187a91%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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/f2d07a43-388b-47b5-9cb3-917d96c97ee6%40www.fastmail.com.