从 Python 输出 JSON 文件。 JSON 文件中的数据混乱答案

【问题标题】：Output JSON file from Python. Data in JSON file messed up从 Python 输出 JSON 文件。 JSON 文件中的数据混乱
【发布时间】：2020-03-10 21:49:38
【问题描述】：

我编写了一些从 SQL 服务器输出 JSON 文件的代码，但 JSON 文件非常混乱。它重复了一些数据，非常混乱：

JSON 输出文件：

[["Name: ", "Trenton", "Age: ", "16", "Losses: ", "0"]][["Name: ", "Trenton", "Age: ", "16", "Losses: ", "0"], ["Name: ", "Max", "Age: ", "15", "Losses: ", "0"]][["Name: ", "Trenton", "Age: ", "16", "Losses: ", "0"], ["Name: ", "Max", "Age: ", "15", "Losses: ", "0"], ["Name: ", "Corbin", "Age: ", "16", "Losses: ", "0"]][["Name: ", "Trenton", "Age: ", "16", "Losses: ", "0"], ["Name: ", "Max", "Age: ", "15", "Losses: ", "0"], ["Name: ", "Corbin", "Age: ", "16", "Losses: ", "0"], ["Name: ", "TJ", "Age: ", "17", "Losses: ", "0"]][["Name: ", "Trenton", "Age: ", "16", "Losses: ", "0"], ["Name: ", "Max", "Age: ", "15", "Losses: ", "0"], ["Name: ", "Corbin", "Age: ", "16", "Losses: ", "0"], ["Name: ", "TJ", "Age: ", "17", "Losses: ", "0"], ["Name: ", "Xander", "Age: ", "16", "Losses: ", "0"]]

代码：

import psycopg2
import json

try:
    connection = psycopg2.connect(user="postgres", password="password", host="192.168.1.88", port="5432", database="losers")
    cursor = connection.cursor()
    postgreSQL_select_Query = "select * from people"

    cursor.execute(postgreSQL_select_Query)
    loss_records = cursor.fetchall()

    lossarray_list = []

    for row in loss_records:
        t = (row[0], row[1], row.[2])
        lossarray_list.append(t)
        with open('data.json', 'a') as out:
            json.dump(lossarray_list, out)


except (Exception, psycopg2.Error) as error:
    print("Error while fetching data from database", error)

finally:
    if(connection):
        cursor.close()
        connection.close()

输出应该类似于下面的链接

[{"Name: ", "Name1", "Age: ", "16", "Losses: ", "0"}],[{"Name: ", "Name2", "Age: ", "16", "Losses: ", "0"}],[{"Name: ", "Name3", "Age: ", "16", "Losses: ", "0"}],[{"Name: ", "Name4", "Age: ", "16", "Losses: ", "0"}],[{"Name: ", "Name5", "Age: ", "16", "Losses: ", "0"}]

发生了什么，我该如何解决？

【问题讨论】：

不要将资源作为外部链接发布。这只会让我们更难提供帮助。
不要在循环中调用json.dump()。将所有内容放在一个列表中，最后对整个内容调用json.dump()。
每次循环时，您都会在lossarray_list 中添加一个新行，然后将整个内容转储到 json 文件中。所以你最终会得到第一行重复 N 次，第二行重复 N-1 次，等等。
小心使用except，就像你在这里一样。参见，例如：stackoverflow.com/questions/54948548/…。

标签： python json formatting

【解决方案1】：

在循环结束时转储整个lossarray_list 一次，而不是每次都转储它。

    lossarray_list = [row[:3] for row in loss_records]
    with open('data.json', 'w') as out:
        json.dump(lossarray_list, out)

【讨论】：