我刚开始玩FastAPI、SQLAlchemy、Pydantic,我正在尝试构建一个简单的API端点,以返回postgis表中的行作为geojson功能集合。
这是我的sqlalchemy
型号:
class Poi(Base):
__tablename__ = 'poi'
id = Column(Integer, primary_key=True)
name = Column(Text, nullable=False)
type_id = Column(Integer)
geometry = Column(Geometry('POINT', 4326, from_text='ST_GeomFromEWKT'),
nullable=False)
使用geojson_pydantic
,相关的pydantic
模型为:
from geojson_pydantic.features import Feature, FeatureCollection
from geojson_pydantic.geometries import Point
from typing import List
class PoiProperties(BaseModel):
name: str
type_id: int
class PoiFeature(Feature):
id: int
geometry: Point
properties: PoiProperties
class PoiCollection(FeatureCollection):
features: List[PoiFeature]
期望输出:
理想情况下,我希望能够检索并返回数据库记录,如下所示:
def get_pois(db: Session, skip: int = 0, limit: int = 100):
return db.query(Poi).offset(skip).limit(limit).all()
@app.get("/geojson", response_model=PoiCollection)
def read_geojson(skip: int = 0,
limit: int = 100,
db: Session = Depends(get_db)):
return get_pois(db, skip=skip, limit=limit)
尽管如此,我还是试图弄清楚如何将数据库模型中的name
和type_id
列映射到PoiFeature
对象中的PoiProperties
。
您希望返回PoiCollection
模式(response_model=schemas.PoiCollection)
,但不需要任何格式即可直接返回数据库响应。因此,您必须将crud响应转换为模式响应。
# Different function for translate db response to Pydantic response according to your different schema
def make_response_poi_properties(poi):
return PoiFeature(name=poi.name, type_id=poi.type_id)
def make_response_poi_feature(poi):
return PoiFeature(id=poi.id, geometry=poi.geometry,properties=make_response_poi_properties(poi))
def make_response_poi_collection(pois):
response = []
for poi in pois:
response.append(make_response_poi_feature(poi)
return response
@app.get("/geojson", response_model=PoiCollection)
def read_geojson(skip: int = 0,
limit: int = 100,
db: Session = Depends(get_db)):
# Call function for translate db data to pydantic data according to your response_model
return make_response_poi_collection(get_pois(db, skip=skip, limit=limit))
或者简单地在不同的模式类中使用orm模式