SQLAlchemy – Mapping self-referential relationship as one to many (declarative form)

by

You add a ForeignKey referencing the parent, and then create a relationship that specifies the direction via remote_side. This is documented under adjacency list relationships. For declarative you’d do something like this:

class Tag(Base):
    __tablename__ = 'tag'

    id = Column(Integer, primary_key=True)
    label = Column(String)
    parent_id = Column(Integer, ForeignKey('tag.id'))

    parent = relationship('Tag', remote_side=[id])

If you want the reverse relation also, add backref="children" to the relationship definition.

More Related Contents:

  1. Writing a connection string when password contains special characters
  2. Does SQLAlchemy have an equivalent of Django’s get_or_create?
  3. How to write DataFrame to postgres table
  4. CS50: LIKE operator, variable substitution with % expansion
  5. SQLAlchemy: What’s the difference between flush() and commit()?
  6. Flask-SQLalchemy update a row’s information
  7. Efficiently updating database using SQLAlchemy ORM
  8. SQLAlchemy ORDER BY DESCENDING?
  9. SQLAlchemy ON DUPLICATE KEY UPDATE
  10. stored procedures with sqlAlchemy
  11. SqlAlchemy – Filtering by Relationship Attribute
  12. How can I profile a SQLAlchemy powered application?
  13. sqlalchemy: create relations but without foreign key constraint in db?
  14. sqlalchemy.exc.NoSuchModuleError: Can’t load plugin: sqlalchemy.dialects:postgres
  15. Strange SQLAlchemy error message: TypeError: ‘dict’ object does not support indexing
  16. Getting first row from sqlalchemy
  17. ImportError: No module named sqlalchemy
  18. Getting random row through SQLAlchemy
  19. Select NULL Values in SQLAlchemy
  20. How to delete a table in SQLAlchemy?
  21. sqlalchemy existing database query
  22. How to get number of affected rows in sqlalchemy?
  23. Flask-SQLAlchemy Constructor
  24. Trigger in sqlachemy
  25. convert selected datetime to date in sqlalchemy
  26. ImportError: cannot import name ‘_ColumnEntity’ from ‘sqlalchemy.orm.query’
  27. Is possible to mapping view with class using mapper in SqlAlchemy?
  28. How to prevent UUID primary key for new SQLAlchemy objects being created with the same value
  29. SQLALchemy dynamic filter_by
  30. SQLAlchemy ordering by count on a many to many relationship

Leave a Comment