使用 Python 在 JSON 中查找值

Question

我之前已经成功地从 JSON 文件中解析数据，但现在我遇到了我想要实现的功能的问题。我有一个 JSON 格式的姓名、身份证号码和生日列表。我想在 Python 中获得的是能够让用户输入姓名并检索他的身份证号和生日（如果存在）。

这是我的 JSON 示例文件：

[
 {
   "id_number": "SA4784",
   "name": "Mark",
   "birthdate": null
 },
 {
   "id_number": "V410Z8",
   "name": "Vincent",
   "birthdate": "15/02/1989"
 },
 {
   "id_number": "CZ1094",
   "name": "Paul",
   "birthdate": "27/09/1994"
 }
]

为了清楚起见，我想输入“V410Z8”并得到他的名字和生日。

我尝试用 Python 编写一些代码，但我只成功搜索了“id_number”，而不是“id_number”中的内容，例如“V410Z8”。

#!/usr/bin/python
# -*- coding: utf-8 -*-

import json 

database = "example.json"
data = json.loads(open(database).read())

id_number = data[0]["id_number"]
print id_number

谢谢你们的支持，伙计们:)

Answer 1

给定

data = [
    {
    "id_number": "SA4784",
    "name": "Mark",
    "birthdate": None               #  the question wrongly contains a null
    },
    {
    "id_number": "V410Z8",
    "name": "Vincent",
    "birthdate": "15/02/1989"
    },
    {
    "id_number": "CZ1094",
    "name": "Paul",
    "birthdate": "27/09/1994"
    }
    ]

要获得“V410Z8”，您可以使用：

[x for x in data if x["id_number"]=="V410Z8"]

结果：

[{'id_number': 'V410Z8', 'name': 'Vincent', 'birthdate': '15/02/1989'}]

Answer 2

data = [
 {
   "id_number": "SA4784",
   "name": "Mark",
   "birthdate": None
 },
 {
   "id_number": "V410Z8",
   "name": "Vincent",
   "birthdate": "14/02/1989"
 },
 {
   "id_number": "CZ1093",
   "name": "Paul",
   "birthdate": "26/09/1994"
 }
]

list(map(lambda x:x if x["id_number"]=="cz1093" ,data)

输出应该是

[{
   "id_number": "CZ1094",
   "name": "Paul",
   "birthdate": "26/09/1994"
 }]

Answer 3

在 Python

中使用 lamda

data = [
 {
   "id_number": "SA4784",
   "name": "Mark",
   "birthdate": None
 },
 {
   "id_number": "V410Z8",
   "name": "Vincent",
   "birthdate": "15/02/1989"
 },
 {
   "id_number": "CZ1094",
   "name": "Paul",
   "birthdate": "27/09/1994"
 }
]

使用 Lambda 和过滤器

print(list(filter(lambda x:x["id_number"]=="CZ1094",data)))

输出

[{'id_number': 'CZ1094', 'name': 'Paul', 'birthdate': '27/09/1994'}]

Answer 4

您必须遍历字典列表并搜索具有给定id_number 的字典。找到它后，您可以打印其其余数据并中断，假设 id_number 是唯一的。

data = [
 {
   "id_number": "SA4784",
   "name": "Mark",
   "birthdate": None
 },
 {
   "id_number": "V410Z8",
   "name": "Vincent",
   "birthdate": "15/02/1989"
 },
 {
   "id_number": "CZ1094",
   "name": "Paul",
   "birthdate": "27/09/1994"
 }
]

for i in data:
    if i['id_number'] == 'V410Z8':
        print(i['birthdate'])
        print(i['name'])
        break

如果您可以控制数据结构，更有效的方法是使用id_number 作为键（再次假设id_number 是唯一的）：

data =  { "SA4784" : {"name": "Mark", "birthdate": None},
          "V410Z8" : { "name": "Vincent", "birthdate": "15/02/1989"},
          "CZ1094" : {"name": "Paul", "birthdate": "27/09/1994"}
        }

那么你需要做的就是尝试直接访问它：

try:
    print(data["V410Z8"]["name"])
except KeyError:
    print("ID doesn't exist")
>> "Vincent"