使用python更新字典值

Question

我有一个json文件，当使用json.loads()加载到python中时，它就变成了一个dictionary。json数据是一个nested dictionary，它可以在另一个'groups'密钥中包含一个'groups'密钥。'groups'密钥中的值是'name'密钥和'properties'密钥。

每个'properties'密钥都有唯一的'name'和'value'密钥。

我的目标是搜索'groups'密钥，其'name'密钥的值为"SportCar"，其properties密钥的name密钥的值为"BMW"，并且仅当满足这些条件时，才将'data'密钥从'data':value1更新为'data':value2。

下面是json的一个示例。

{
  "groups": [
    {
      "name": "SportCar",
      "properties": [
        {
          "name": "BMW",
          "value": {
            "type": "String",
            "encoding": "utf-8",
            "data": "value1"
          }
        },
        {
          "name": "Audi",
          "value": {
            "type": "Boolean",
            "data": true
          }
        }
      ],
      "groups": [
        {
          "name": "Trucks",
          "properties": [
            {
              "name": "Volvo",
              "value": {
                "type": "String",
                "encoding": "utf-8",
                "data": "value1"
              }
            }
          ]
        }
      ]
    },
    {
      "name": "MotorCycle",
      "properties": [
        {
          "name": "Yamaha",
          "value": {
            "type": "String",
            "encoding": "utf-8",
            "data": "value1"
          }
        }
      ],
      "groups": [
        {
          "name": "Speeders",
          "properties": [
            {
              "name": "prop2",
              "value": {
                "type": "String",
                "encoding": "utf-8",
                "data": "value1"
              }
            }
          ]
        }
      ]
    }
  ]
}

上面的json包含在myjson22.json中。这是我到目前为止尝试过的：

import json
from pprint import pprint

json_data=open('myjson22.json', 'r')
data = json.load(json_data)
#print(data)

def get_recursively(search_dict, field):
    """
    To read the json data as type dict and search all 'groups' keys for the 'name' key value value provided.
    """
    fields_found = []

    for key, value in search_dict.items():

        if key == field:
            fields_found.append(value)

        elif isinstance(value, dict):
            results = get_recursively(value, field)
            for result in results:
                fields_found.append(result)

        elif isinstance(value, list):
            for item in value:
                if isinstance(item, dict):
                    more_results = get_recursively(item, field)
                    for another_result in more_results:
                        fields_found.append(another_result)

    return fields_found
get_recursively(data, ["properties"][0])

输出结果是：

 [[{'name': 'BMW',
   'value': {'data': 'value1', 'encoding': 'utf-8', 'type': 'String'}},
  {'name': 'Audi', 'value': {'data': True, 'type': 'Boolean'}}],
 [{'name': 'Volvo',
   'value': {'data': 'value1', 'encoding': 'utf-8', 'type': 'String'}}],
 [{'name': 'Yamaha',
   'value': {'data': 'value1', 'encoding': 'utf-8', 'type': 'String'}}],
 [{'name': 'prop2',
   'value': {'data': 'value1', 'encoding': 'utf-8', 'type': 'String'}}]]

Answer 1

实现这种递归解决方案的一种方法是回溯。当在根键中找不到嵌套的'groups'键时，'name'键值将与groups_name参数匹配，在本例中该参数为'SportCar‘。如果满足此条件，请检查相同'groups'键中的值(即'SportCar‘键) 'properties'键，并将其'name'键值与properties_name参数(在本例中为'BMW’)进行匹配。如果第二个条件也为真，则根据需要更新同一个'properties'键中的'data'键值，否则返回(用于回溯)。

import json

json_data = open('myjson22.json', 'r')

data = json.load(json_data)

def get_recursively( myJson, groups_name, properties_name, value2):

    if 'groups' in myJson.keys():
        # As there are multiple values inside 'groups' key
        for jsonInsideGroupsKey in myJson['groups']:  
            get_recursively( jsonInsideGroupsKey, groups_name, properties_name, value2)

    if 'name' in myJson.keys():
        # check for groups name
        if myJson['name'] == groups_name:
            # check for properties name
            if myJson['properties'][0]['name'] == properties_name:
                # Update value. The changes will persist as we backtrack because
                # we are making the update at the original memory location
                # and not on a copy. For more info see deep and shallow copy.
                myJson['properties'][0]['value']['data'] = value2
    return

get_recursively(data,'SportCar','BMW','changedValue1')
get_recursively(data,'Speeders','prop2','changedValue2')
print data

我的输出：

{u‘’groups‘：[{u’‘name’：u‘’SportCar‘，u’‘groups’：[{u‘’name‘：u’‘Trucks’，u‘’properties‘：{u’‘name’：u‘’Volvo‘，u’‘value’：{u‘’data‘：u'value1'，u’‘type’：u‘’String‘，u’‘encoding’：u‘’utf 8‘}}]]，u’‘properties’：{u‘’name‘：u’‘BMW’，u‘’value‘：{u’‘data’：'changedValue1'，U‘类型’：u‘字符串’，u‘编码’：u‘’utf 8‘}}，{u’‘name’：u‘’Audi‘，u’‘value’：{u‘’data‘：True，u’‘type’：u‘’Boolean‘}，{u’‘name’：u‘’MotorCycle‘，u’‘groups’：[{u‘’name‘：u’‘Speeders’，u‘’properties‘：{u’‘name’：u'prop2'，u‘’value‘：{u’‘data’：'changedValue2'，U‘类型’：u‘字符串’，u‘编码’：u‘’utf 8‘}]，u’‘properties’：{u‘’name‘：u’‘Yamaha’，u‘’value‘：{u’‘data’：u'value1'，u‘’type‘：u’‘String’，u‘编码’：u‘’utf 8‘}

经过美化后，它看起来会像这样：

{
  "groups": [
    {
      "name": "SportCar",
      "properties": [
    {
      "name": "BMW",
      "value": {
        "type": "String",
        "encoding": "utf-8",
        "data": "ChangedValue1"
      }
    },
    {
      "name": "Audi",
      "value": {
        "type": "Boolean",
        "data": true
      }
    }
      ],
      "groups": [
    {
      "name": "Trucks",
      "properties": [
        {
          "name": "Volvo",
          "value": {
            "type": "String",
            "encoding": "utf-8",
            "data": "value1"
          }
        }
      ]
    }
      ]
    },
    {
      "name": "MotorCycle",
      "properties": [
    {
      "name": "Yamaha",
      "value": {
        "type": "String",
        "encoding": "utf-8",
        "data": "value1"
      }
    }
      ],
      "groups": [
    {
      "name": "Speeders",
      "properties": [
        {
          "name": "prop2",
          "value": {
            "type": "String",
            "encoding": "utf-8",
            "data": "ChangedValue2"
          }
        }
      ]
    }
      ]
    }
  ]
}