使用Flask + GeoAlchemy2应用程序返回有效的GeoJSON
使用Flask + GeoAlchemy2应用程序返回有效的GeoJSON
提问于 2020-07-01 04:39:32
这几天我一直在想如何让我的Flask应用程序返回有效的GeoJSON，这是我到目前为止得到的：
models.py
class Building(base):
__tablename__ = 'buildings'
id = Column(Integer, primary_key=True)
district = Column(Unicode)
address = Column(Unicode)
name = Column(Unicode)
building_type = Column(Unicode)
mpoly = Column(Geometry('MULTIPOLYGON'))
building = relationship("User")
# this part is done as answered here: https://stackoverflow.com/questions/41684512/cant-transform-geometry-to-geojson
def building_to_dict(self):
return mapping(shapely.wkb.loads(str(self.mpoly), True))
def __str__(self):
d = dict()
d["id"] = self.id
d["district"] = self.district
d["address"] = self.address
d["name"] = self.name
d["building_type"] = self.building_type
d["mpoly"] = self.building_to_dict()
return shapely.dumps(d)现在，在main文件中，我有以下路径：
app.py
@app.route('/geojson')
def get_json():
features = session.query(Building.mpoly.ST_AsGeoJSON()).all()
return jsonify(features)这是我的两个问题：
1)返回类似JSON的响应，内容如下："{\"type\":\"MultiPolygon\",\"coordinates\":[[[[16.8933137,52.471446],...,]]]}"不是正确的GeoJSON。jsonify之前的特性变量是这样的：[('{"type":"MultiPolygon","coordinates":[[[[16.914159616,52.473822807],...,]]]}',)]
2)我的GeoAlchemy查询应该是什么样子，不仅返回几何字段，还返回其他字段？
如有任何提示或帮助，敬请期待，谢谢！
回答 1
Stack Overflow用户
发布于 2020-08-07 15:22:46
您可以使用marshmallow-sqlalchemy来创建类似json的响应。
创建schemas.py
#!schemas.py
from marshmallow import fields
from marshmallow_sqlalchemy import ModelSchema
from app.models import Building
from geoalchemy.shape import to_shape
class BuildingSchema(ModelSchema):
id = fields.Integer()
district = fileds.Unicode()
address = fileds.Unicode()
name = fields.Unicode()
building_type = fields.Unicode()
mpoly = fileds.Method("geom_to_json")
@staticmethod
def geom_to_json(obj):
mpoly = to_shape(obj.mpoly)
return {
lat: mpoly.y,
lon: mpoly.x,
#and so on ...
}
class Meta:
model = Building
exclude = ("mpoly")
bulding_schema = BuildingSchema(many=True)在此之后，您可以在视图(路由)中使用它
from app.schemas import building_schema
@app.route('/geojson')
def json():
buildings = Buildings.query.all()
response = building_schema.dumps(buildings)
return response页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/62665818
复制相关文章
相似问题
腾讯云开发者
