任何人都可以提供任何带有 GeoAlchemy 的 Flask 示例代码吗?
问问题
6922 次
3 回答
22
使用 SQLAlchemy 0.8、Flask-SQLAlchemy 和 Geoalchemy 2:
from app import db
from geoalchemy2.types import Geometry
class Point(db.Model):
"""represents an x/y coordinate location."""
__tablename__ = 'point'
id = db.Column(db.Integer, primary_key=True)
geom = db.Column(Geometry(geometry_type='POINT', srid=4326))
示例查询:
from geoalchemy2.elements import WKTElement
from app import models
def get_nearest(lat, lon):
# find the nearest point to the input coordinates
# convert the input coordinates to a WKT point and query for nearest point
pt = WKTElement('POINT({0} {1})'.format(lon, lat), srid=4326)
return models.Point.query.order_by(models.Point.geom.distance_box(pt)).first()
将结果转换为 x 和 y 坐标的一种方法(转换为 GeoJSON 并提取坐标):
import geoalchemy2.functions as func
import json
from app import db
def point_geom_to_xy(pt):
# extract x and y coordinates from a point geometry
geom_json = json.loads(db.session.scalar(func.ST_AsGeoJSON(pt.geom)))
return geom_json['coordinates']
于 2013-04-19T00:32:10.297 回答
1
你可以将它与Flask-SQLAlchemy一起使用,但你也可以将它与普通的 SQLAlchemy 一起使用。只需将示例模型从 GeoAlchemy 转换为 Flask-SQLAlchemy。像这样的东西:
class Spot(db.Model):
__tablename__ = 'spots'
id = db.Column(Integer, primary_key=True)
name = db.Column(Unicode, nullable=False)
height = db.Column(Integer)
created = db.Column(DateTime, default=datetime.now())
geom = db.GeometryColumn(Point(2))
我没有测试过代码,但它应该是一个公平的转录。
于 2012-01-30T18:15:35.783 回答
0
from myapp import db
from geoalchemy import GeometryColumn, Point
class FixXX(db.Model):
__tablename__ = 'fixXX'
fix_pk = db.Column(db.Integer, primary_key=True)
fix = db.Column(db.String)
geometry = GeometryColumn(Point(2, srid=4326))
GeometryDDL(FixXX.__table__)
于 2012-10-23T23:21:45.360 回答