Hybrid property

hybridprop.py

class Platform(db.Model, ModelMixin):
    __tablename__ = 'platform'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(200), nullable=False, index=True)
    homepage = db.Column(db.String(200))
    description = db.Column(db.Text)

    @property
    def versions_ordered(self):
        return self.versions.order_by(db.desc(PlatformVersion.release_date))

    @property
    def version_count(self):
        return self.versions.count()

    @property
    def latest_version(self):
        return self.versions.order_by(db.desc(PlatformVersion.version_str)).first()

    @hybrid_property
    def report_count(self):
        return sum([x.reports.count() for x in self.versions])

    @report_count.expression
    def report_count(cls):
        return db.select([db.func.count(Report.id)]).\
            where(db.and_(Report.platformversion_id==PlatformVersion.id, PlatformVersion.platform_id==cls.id)).\
            label('report_count')