J'utilise flask_sqlalchemy et flask_restless pour créer un point de terminaison API pour accéder aux données d'une base de données PostgreSQL. Comment puis-je construire la requête SQL suivante dans flask-agile?Comment construire une requête SQL "group_by" dans flask-agité?
SELECT AVG("SpeedBand"), "Location"
FROM public.traffic_data
WHERE "RoadName"='ABC ROAD'
GROUP BY "Location"
Cela renvoie toutes les paires de coordonnées qui appartiennent à "ABC ROAD" et la vitesse moyenne sur chaque paire de coordonnées:
avg | Location
------------------------
1)'1.52' | 'X1 Y1 X2 Y2'
2)'1.85' | 'X3 Y3 X4 Y4'
------------------------
Actuellement, cette requête:
http://127.0.0.1:5000/api/traffic_data?q={"filters":[{"name":"RoadName","op":"==","val":"ABC ROAD"}]}
Retours une chaîne JSON de toutes les données qui appartiennent à "ABC ROAD" et toutes les données de vitesse à des moments différents:
{
"num_results": 26,
"objects": [
{
"DateTime": "2017-09-07T19:25:37.035325",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 3,
"id": 34094
},
{
"DateTime": "2017-09-07T19:25:37.035325",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 1,
"id": 38003
},
{
"DateTime": "2017-09-13T09:57:07.163900",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 1,
"id": 92874
},
{
"DateTime": "2017-09-13T09:57:07.163900",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 1,
"id": 96783
},
{
"DateTime": "2017-09-13T09:57:07.163900",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 1,
"id": 114755
},
{
"DateTime": "2017-09-13T09:57:07.163900",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 114756
},
{
"DateTime": "2017-09-13T10:08:17.727949",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 151654
},
{
"DateTime": "2017-09-13T10:08:17.727949",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 155563
},
{
"DateTime": "2017-09-13T10:19:39.040191",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 210434
},
{
"DateTime": "2017-09-13T10:19:39.040191",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 214343
},
{
"DateTime": "2017-09-13T10:27:51.307349",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 269214
},
{
"DateTime": "2017-09-13T10:42:36.724985",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 327994
},
{
"DateTime": "2017-09-13T10:42:36.724985",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 331903
},
{
"DateTime": "2017-09-13T10:42:36.724985",
"LinkID": "109002906",
"Location": "X1 Y1 X2 Y2",
"RoadName": "ABC ROAD",
"SpeedBand": 1,
"id": 349875
},
{
"DateTime": "2017-09-13T10:42:36.724985",
"LinkID": "109002907",
"Location": "X3 Y3 X4 Y4",
"RoadName": "ABC ROAD",
"SpeedBand": 2,
"id": 349876
},
. . .
],
"page": 1,
"total_pages": 1
}
Ne pouvez-vous pas définir votre propre point de terminaison pour exécuter ce SQL exactement? –
Je peux écrire la même requête dans SQLAlchemy 'result = session.query (fonc.avg (TrafficData.SpeedBand), TrafficData.Location) .group_by (TrafficData.Location) .filter (TrafficData.RoadName == 'ABC ROAD') .all() ' mais comment dois-je écrire cela dans le point de terminaison? [link] (https://flask-restless.readthedocs.io/fr/stable/customizing.html) –
Vous pouvez écrire cela dans une méthode ... https://flask-restless.readthedocs.io/en/ stable/customizing.html # custom-queries –