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I encountered in a book some explanation how self referential tables in SQLAlchemy (Python) work, as an example, here is the class Employee with a manager_id:

class Employee(Base):
    __tablename__ = 'employees'
    id = Column(Integer(), primary_key=True)
    manager_id = Column(Integer(), ForeignKey('employees.id'))
    name = Column(String(255), nullable=False)
    manager = relationship("Employee", backref=backref('reports'),
    remote_side=[id])

unfortunately, I still don't really understand how this works.. In this case I guess every Employee can be a manager (with a manager_id) and Employee contains a reference to a manager, but what means backref=backref('reports') and what is reports? Is it another table? and what is remote_side=[id] in this case? does it reference to the employer.id, so to say that your manager manages some specific employer.id or the other way around, that each employer.id has some manager with a manager_id?

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    I know how the official docs are sometimes hard to get through or to find what you need => but for this case, the official SQL Alchemy docs have pretty good desc of this docs.sqlalchemy.org/en/13/orm/backref.html - especially they show you what is the EXACT EQUIVALENT if you would not use backref - that and the texts around it should answer all your questions :)
    – jave.web
    Jan 10 '20 at 22:18
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It just means that the inverted relation to "manager" is "reports" (an employee reports to a manager). The remote_side just says what column is used in the "remote" table (which is Employee again in this case) to establish the relationship.

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  • ok and what does backref=backref("reports") mean in that case? Is it just a saved list reference to some "reports" list, where you can append the employees that report to some manager?
    – Marc_L
    Nov 25 '17 at 14:16

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