Question

我有一个模型的几何点列，所以我想定义setter来接收lat / lng而不是创建的WKTElement。这是我的模型目前的样子：

class Poi(db.Model):
    __tablename__ = 'api_pois'

    id = db.Column(db.Integer, primary_key=True, unique=True)
    name = db.Column(db.String(80), nullable=False)
    user_id = db.Column(db.Integer, db.ForeignKey('api_users.id'))
    creation_time = db.Column(db.DateTime, default=func.now())
    category_id = db.Column(db.Integer(), db.ForeignKey('api_poi_categories.id'))
    category = db.relationship('PoiCategory')
    geom = db.Column(Geometry('POINT', srid=4326), nullable=False)
    metadata_poi = db.Column('metadata_poi')

    def __init__(self, name, lat, lng, user_id=None, category_id=None, metadata_poi=None):
        geom_str = 'POINT({} {})'.format(lng, lat)
        self.name = name
        self.user_id = user_id
        self.category_id = category_id
        self._geom = WKTElement(geom_str, srid=4326)
        self.metadata_poi = metadata_poi

    def __repr__(self):
        return '<Poi %r %r>' % (self.id, self.name)

    def as_dict(self, route_id=None):
        sequence = None

        if route_id:
            from sintrafico.models.route import routes_pois

            result = db.session.query(routes_pois).filter_by(route_id=route_id, poi_id=self.id). \
                order_by(routes_pois.c._sequence).one_or_none()

            if result:
                sequence = result[2]

        geom = db.session.query(Poi, func.ST_X(self.geom), func.ST_Y(self.geom)).filter(Poi.id == self.id).one_or_none()

        return {
            'id': self.id,
            'name': self.name if not sequence else '%s - %s' % (sequence, self.name),
            'lat': geom[2],
            'lon': geom[1],
            'city': str(City.city_for_coord(geom[2], geom[1])),
            'sequence': sequence if sequence else None,
            'category_id': self.category_id,
            'category': self.category.name,
            'metadata': self.metadata_poi
        }

    @property
    def location(self):
        geom = db.session.query(Poi, func.ST_X(self.geom), func.ST_Y(self.geom)).filter(Poi.id == self.id).one_or_none()
        return {'lat': geom[2], 'lon': geom[1]}

    @hybrid_property
    def geom(self):
        return self._geom

    @geom.setter
    def geom(self, (lat, lng)):
        geom_str = 'POINT({} {})'.format(lng, lat)
        self._geom = WKTElement(geom_str, srid=4326)

此代码在调用混合getter的geom = ...内的as_dict()行失败，因为Poi对象没有属性_geom。现在，如果我将行更改为

geom = db.session.query(Poi, func.ST_X(self._geom), func.ST_Y(self._geom)).filter(Poi.id == self.id).one_or_none()

错误仍然存在，只是移动到该行而不是setter。如果我将声明更改为

_geom = db.Column(Geometry('POINT', srid=4326), nullable=False)

然后我得到的错误是格式错误的查询：

HINT:  Perhaps you meant to reference the column "api_pois.geom".
 [SQL: 'SELECT api_pois.id AS api_pois_id, api_pois.name AS api_pois_name, api_pois.user_id AS api_pois_user_id, api_pois.creation_time AS api_pois_creation_time, api_pois.category_id AS api_pois_category_id, ST_AsBinary(api_pois._geom) AS api_pois__geom, api_pois.metadata_poi AS api_pois_metadata_poi \nFROM api_pois \nWHERE api_pois.user_id = %(user_id_1)s ORDER BY api_pois.creation_time DESC'] [parameters: {'user_id_1': 1}]

在此代码的最后一行：

if args['q']:
    pois = pois.filter(func.lower(Poi.name).like('%{}%'.format(args['q'].lower())))

if args['categories'] is not None and len(args['categories']) > 0:
    pois = [x for x in pois if x.category_id in args['categories']]

我怎样才能让它发挥作用？

Answer 1

明确命名您的geom列，而不是让声明性使用属性名称：

class Poi(db.Model):
    ...
    _geom = db.Column('geom', Geometry('POINT', srid=4326), nullable=False)

SQLAlchemy混合属性无法正常工作

1 个答案: