如何从SQLAlchemy模型确定子对象的类型？

Question

I have the following SQLAlchemy model:

class PersonConsent(ModelAbstract):
    __tablename__ = "personConsent"
    id = db.Column(db.Integer, primary_key=True)
    patientId = db.Column(db.Integer, db.ForeignKey("person.id"))
    authorizedPersonId = db.Column(db.Integer, db.ForeignKey("person.id"))
    attachmentId = db.Column(db.Integer)

    # Additional models
    authorizedPerson = db.relationship("Person", foreign_keys=[authorizedPersonId])
    consents = db.relationship("PersonConsentType", 
                secondary=personConsentToTypeMap,
                primaryjoin=id==personConsentToTypeMap.c.consentId,
                secondaryjoin=PersonConsentType.id==personConsentToTypeMap.c.consentTypeId)

Given just the PersonConsent model how do I determine the model of items that make up the consents field?

For example, something like

type(PersonConsent.consents) == PersonConsentType

Answer 1

Use the inspect function and follow the correct attributes to get the target model for a relationship.

from sqlalchemy import inspect

mapper = inspect(PersonConsent)
property = mapper.relationships['consents']
target = property.mapper.class_

assert target is PersonConsentType

You can technically get to this by doing PersonConsent.consents.property.mapper.class_ , but it's less general. You could use the inspection above to, for example, loop over all the relationships, even if you don't know their names.