如何使用 flask 和 jsonify 在 json 响应中添加嵌套数组和对象

Question

我目前正在关注此 example 以获得 API 和运行（我的代码如下）

from flask import Flask, request, jsonify
from flask_restful import Resource, Api
from sqlalchemy import create_engine
from json import dumps


import mysql.connector

db_connect = create_engine('mysql+pymysql://root:pass@localhost/news')

app = Flask(__name__)
api = Api(app)

class Events(Resource):
    def get(self):

        conn = db_connect.connect() # connect to database
        query = conn.execute("select id, title, description, date, scheduled,favourite,count_audio,count_video,count_articles from events;")
        result = [dict(zip(tuple (query.keys()) ,i)) for i in query.cursor]
        return jsonify(result)

api.add_resource(Events, '/events') # Route_1


if __name__ == '__main__':
     app.run(port='5002')

我想得到一个嵌套数组 tags 和一个嵌套对象 location，如下所示

[{
    "description": "TEST DESCRIPTION",
    "id": 1,
    "title": "TEST TITLE",
    "date": "2020-09-02",
    "scheduled":"true",
    "favourite":"true",
    "tags": ["celebration", "national holiday"],
    "location": {
        "state": {
            "name": "new zealand",
            "affiliation": ["United Nations"]
        },
        "province": "",
        "urbanisation": "Wellington"
        }
},
{
    "description": "LONG DESCRIPTION",
    "id": 2,
    "title": "SECOND ENTRY",
    "date": "2020-09-03",
    "scheduled":"false",
    "favourite":"false",
    "tags": ["election", "national holiday"],
    "location": {
        "state": {
            "name": "Brazil",
            "affiliation": [""]
        },
        "province": "",
        "urbanisation": ""
        }
}]

这样的事情有可能吗？我是否需要重新考虑 API 让端点覆盖每个嵌套对象？

api.add_resource(Events, '/events')
api.add_resource(tags, '/events/tag')
api.add_resource(location, '/events/location')

或者，我是否像那样嵌套字典。

Answer 1

是的，它可能而且完全有效。但我不会直接查询数据库。我会使用像 SQLAlchemy, for flask use can use flask-sqlalchemy extension. The serialization can be achieved using flask-marshmallow

这样的 ORM

使用 SQLAlchemy 创建模型：

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)

class EventModel(db.Model):
    __tablename__ = "event"

    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String, nullable=True)


class LocationModel(db.Model):
    __tablename__ = "location"

    id = db.Column(db.Integer, primary_key=True)
    province = db.Column(db.String, nullable=True)

    event_id = db.Column(db.Integer, db.ForeignKey("event.id", ondelete="CASCADE"), nullable=False)

    event = db.relationship("EventModel", backref=db.backref("locations", lazy=True))

然后你需要序列化器类（使用flask-marshmallow）来处理序列化：

from marshmallow_sqlalchemy import SQLAlchemyAutoSchema, fields
from marshmallow_sqlalchemy import auto_field
class LocationSchema(SQLAlchemyAutoSchema):
    class Meta:
        model = LocationModel
        load_instance = True
        include_fk = False

    id = auto_field(load_only=True)

class EventSchema(SQLAlchemyAutoSchema):
    class Meta:
        model = EventModel
        load_instance = True
        include_fk = False

    id = auto_field(load_only=True)
    locations = fields.Nested(LocationSchema, many=True)

最后，您可以序列化为 json，如下所示：

db.drop_all()
db.create_all()
event = EventModel(title="Summer Show")
db.session.add(event)
db.session.commit()
location1 = LocationModel(province="Upper Austria", event_id=event.id)
db.session.add(location1)
location2 = LocationModel(province="Tirol", event_id=event.id)
db.session.add(location2)
db.session.commit()


schema = EventSchema()
result = db.session.query(EventModel).all()
print(schema.dump(result, many=True))

可以找到完整的教程 here。

如何使用 flask 和 jsonify 在 json 响应中添加嵌套数组和对象

How can you add nested arrays and objects within json responses using flask and jsonify

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python-3.8