将元组改为字典，如何正确设置键值？

Question

我使用SQLAlchemy在MySQL数据库中插入数据并对其进行查询。当我这样做的时候

result = db.engine.execute(query).fetchall()它给出了元组列表，如下所示

我想知道，当我将每个元组改为字典时，result = [(1, canada, toronto,...), (2, canada, vancouver,....),....]是如何正确地分配适当的键的。

这是我的python代码：

with open('static/db/final_cities_countries.json') as f:
        data = json.load(f)

    # if data exists grab data, if not query again and store into db, then grab data
    query = db.select([Aqi]).where(Aqi.Country == country)
    result = db.engine.execute(query).fetchall()
    if len(result) < 1:
        list_of_cities = data[country]
        for city in list_of_cities:
            # store into db if aqi_call is ONLY successful with status:ok
            if get_aqi(city) != None:
                aqi_response = get_aqi(city)
                lat = aqi_response['data']['city']['geo'][0]
                lng = aqi_response['data']['city']['geo'][1]
                time = aqi_response['data']['time']['s']

                # creating instance of Aqi class(row in MySQL table) and inserting into aqi table
                aqi_data = Aqi(country, city, aqi_response['data']['aqi'], lat, lng, time)
                db.session.add(aqi_data)
                db.session.commit()
        # this time it will have more  
        query = db.select([Aqi]).where(Aqi.Country == country)

        # result = [(id, country, city,...), (id, country, city,...), ...etc.]
        result = db.engine.execute(query).fetchall()

    # sending back list of dictionaries. [{id:x, country:y, city:z,...}, {},{},...]
    return jsonify([dict(row) for row in result])

当我更改每个元组时，它会正确地返回

[{id:1, country: canada, city:toronto,...}, {id:2, country:canada, city: vancouver,...},...]

在将元组转换为字典时，我们从未指定键名，它是如何知道的？

Answer 1

它们不是普通的tuple，而是行为既像元组又像有序映射的RowProxy实例。字符串键派生自查询中的列名。