How to tell if a InstrumentedAttribute is a relation in sqlalchemy?

问题

Given a sqlalchemy model class

class Table(Base):
  __table__name = 'table'
  col1 = Column(...)

  rel = relationship(...)

If you look at Table, both col1 and rel are of type InstrumentedAttribute. How can I distinguish these two? I tried to look into their attributes. But there are too many...and there's no document about this matter.

回答1:

Check the type of Table.<column>.property which can commonly be either instance of ColumnProperty or RelationshipProperty:

>>> type(Table.col1.property)
<class 'sqlalchemy.orm.properties.ColumnProperty'>
>>> type(Table.rel.property)
<class 'sqlalchemy.orm.relationships.RelationshipProperty'>

来源：https://stackoverflow.com/questions/26572268/how-to-tell-if-a-instrumentedattribute-is-a-relation-in-sqlalchemy