使用flask_sqlalchemy，建立多个relationship，报错'dynamic' loaders cannot be used with many-to-one/one-.......

建立relationship时使用db.backref(‘xxx’, lazy='dynamic)

class User(db.Model):
    """用户"""
    __tablename__ = "user"

    ID = db.Column(db.Integer, primary_key=True, unique=True, nullable=False)
    UserName = db.Column(db.String(32), nullable=False)
    Password = db.Column(db.String(128), nullable=False)
    Name = db.Column(db.String(32))
    Mobile = db.Column(db.String(11))
    Email = db.Column(db.String(50))
    IdCard = db.Column(db.String(20))
    UserType = db.Column(db.Integer)
    CreatorId = db.Column(db.Integer)
    AvatarUrl = db.Column(db.String(128))
    IsDelete = db.Column(db.Integer, default=0)
    CreateTime = db.Column(db.DateTime, nullable=False, default=datetime.now)
    ModifyTime = db.Column(db.DateTime, default=datetime.now, onupdate=datetime.now)
    Boards = db.relationship('Board', secondary=user_board, backref=db.backref('Users', lazy='dynamic'))
    GroupId = db.Column(db.Integer, db.ForeignKey('group.ID'), nullable=True)
    SiteId = db.Column(db.Integer, db.ForeignKey('equipment_site.ID'))
    Site = db.relationship('EquipmentSite', backref=db.backref('Users', lazy='dynamic'))
    CustomsId = db.Column(db.Integer, db.ForeignKey('equipment_customs.ID'))
    Customs = db.relationship('EquipmentCustoms', backref=db.backref('Users', lazy='dynamic'))
    SceneId = db.Column(db.Integer, db.ForeignKey('equipment_scene.ID'))
    Scene = db.relationship('EquipmentScene', backref=db.backref('Users', lazy='dynamic'))