无法使用 python 从 Json 文件中获取特定值答案

【问题标题】：Not able to get specific value from Json file using python无法使用 python 从 Json 文件中获取特定值
【发布时间】：2019-10-03 10:11:48
【问题描述】：

我很难从我的 json 文件中获取一些数据。我能够获取一些数据，但是当我想深入挖掘更多细节时，我遇到了错误并且卡在了哪里。

运行下面的脚本返回错误

AttributeError: 'list' object has no attribute 'get'

我知道它是一个列表，但我不确定如何获取对象列表的其余部分。

脚本

ifile=open('source.json', 'r')
ofile=open('extract.json', 'w')
json_decode=json.load(ifile)
myresult=[]
for item in json_decode:
    mydict={}
    mydict['sID']=item.get('Ls id')
    my_dict['dID']=item.get('items').get('Link ID').get('Metric').get('Link Type')
    mydict['type']=item.get('Type')
    myresult.append(mydict)
myjson=json.dumps(myresult, ofile)
ofile.write(myjson)
ofile.close()

源 Json 文件

[
  {
    "Ls age": "201",
    "items": [
      {
        "Link ID": "1.1.1.2",
        "Link Type": "StubNet",
        "Metric": "1",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.4",
        "Link Type": "P-2-P",
        "Metric": "1",
        "Data": "192.168.100.34"
      },
      {
        "Link ID": "192.168.100.33",
        "Link Type": "StubNet",
        "Metric": "1",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.1",
        "Link Type": "P-2-P",
        "Metric": "1",
        "Data": "192.168.100.53"
      }
    ],
    "Len": "84",
    "Ls id": "1.1.1.2",
    "Adv rtr": "1.1.1.2",
    "Type": "Router",
    "Link count": "5"
  },
  {
    "Ls age": "1699",
    "seq#": "80008d72",
    "items": [
      {
        "Link ID": "1.1.1.1",
        "Link Type": "StubNet",
        "Metric": "1",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.1",
        "Link Type": "StubNet",
        "Metric": "12",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.3",
        "Link Type": "P-2-P",
        "Metric": "10",
        "Data": "192.168.100.26"
      },
      {
        "Link ID": "192.168.100.25",
        "Link Type": "StubNet",
        "Metric": "10",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.2",
        "Link Type": "P-2-P",
        "Metric": "10",
        "Data": "192.168.100.54"
      },
      {
        "Link ID": "192.168.100.53",
        "Link Type": "StubNet",
        "Metric": "10",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      }
    ],
    "Len": "96",
    "Ls id": "1.1.1.1",
    "chksum": "0x16fc",
    "Adv rtr": "1.1.1.1",
    "Type": "Router",
    "Options": "ASBR  E",
    "Link count": "6"
  }
]

预计结果如下

[
  {
    "type": "Router",
    "sID": "1.1.1.2",
    "dID": "1.1.1.2",
    "LinkType":"StubNet",
    "Metric":"1"
  },
  { 
    "type": "Router",
    "sID": "1.1.1.2", 
    "dID": "1.1.1.4",
    "Link Type": "P-2-P",
    "Metric": "1"
  },
  {
    "type": "Router",
    "sID": "1.1.1.2",
    "dID": "192.168.100.33",
    "LinkType":"StubNet",
    "Metric":"1"   
  },   
  { 
    "type": "Router",     
    "sID": "1.1.1.2",     
    "dID":"1.1.1.1",
    "Link Type": "P-2-P",
    "Metric": "1"
  },
  {
    "type": "Router",
    "sID": "1.1.1.1",
    "dID": "1.1.1.1",     
    "LinkType":"StubNet",     
    "Metric":"1"  
   },   
   {     
    "type": "Router",
    "sID": "1.1.1.1",
    "dID":"1.1.1.1",
    "Link Type": "StubNet",
    "Metric": "12"
  },
  {
    "type": "Router",
    "sID": "1.1.1.1",
    "dID": "1.1.1.3",
    "LinkType":"P-2-P",
    "Metric":"10"   
  } 
]

感谢您建议如何进一步进行。我四处搜索并尝试错误，但仍然无法解决它。感谢您的建议和支持。谢谢

【问题讨论】：

标签： python json list extract

【解决方案1】：

您应该能够像字典一样访问值，例如：

ifile=open('source.json', 'r')
ofile=open('extract.json', 'w')
json_decode=json.load(ifile)
myresult=[]
for item in json_decode:
    mydict={}
    mydict['sID']=item['Ls id']
    my_dict['dID']=item['items']['Link ID']['Metric']['Link Type']
    mydict['type']=item['Type']
    myresult.append(mydict)
myjson=json.dumps(myresult, ofile)
ofile.write(myjson)
ofile.close()

这对你有用吗？如果没有，您遇到了什么错误？

【讨论】：

您好先生..谢谢您的回复和帮助...我收到错误 mydict['dID']=item['items']['Link ID']['Metric' ]['Link Type'] TypeError: 列表索引必须是整数，而不是str

【解决方案2】：

您需要遍历设备，然后遍历设备['items']

import json

with open('source.json', 'r') as ifile:
    json_data=json.load(ifile)

my_result=[]

for device in json_data:
    for item in device.get('items', []):
        my_dict={}
        my_dict['type'] = device.get('Type')
        my_dict['sID'] = device.get('Ls id')
        my_dict['dID'] = item.get('Link ID')
        my_dict['Link Type'] = item.get('Link Type')
        my_dict['Metric'] = item.get('Metric')
        my_result.append(my_dict)

with open('extract.json', 'w') as ofile:
    json.dump(my_result, ofile, indent=4)

对于更结构化的代码，您可能需要定义一个以设备/项目作为参数的函数，对其进行解析并返回一个字典/字典列表

【讨论】：

【解决方案3】：

首先，您将在item['items'] 中获得一个列表。您需要决定是否需要保存该列表中的所有可用值。

其次，您尝试一次访问 dict 中的多个属性，但您正在链接 get 命令。然而，该代码试图将其视为嵌套字典，并且会遇到数据类型错误。

第三，您实际上不需要像那样输入get，更简洁的版本是只使用方括号表示法。

假设您需要为item['items'] 列表中的每个项目创建一个新的字典，解决方案将如下所示：

import json
s = '''
[
  {
    "Ls age": "201",
    "items": [
      {
        "Link ID": "1.1.1.2",
        "Link Type": "StubNet",
        "Metric": "1",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.4",
        "Link Type": "P-2-P",
        "Metric": "1",
        "Data": "192.168.100.34"
      },
      {
        "Link ID": "192.168.100.33",
        "Link Type": "StubNet",
        "Metric": "1",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.1",
        "Link Type": "P-2-P",
        "Metric": "1",
        "Data": "192.168.100.53"
      }
    ],
    "Len": "84",
    "Ls id": "1.1.1.2",
    "Adv rtr": "1.1.1.2",
    "Type": "Router",
    "Link count": "5"
  },
  {
    "Ls age": "1699",
    "seq#": "80008d72",
    "items": [
      {
        "Link ID": "1.1.1.1",
        "Link Type": "StubNet",
        "Metric": "1",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.1",
        "Link Type": "StubNet",
        "Metric": "12",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.3",
        "Link Type": "P-2-P",
        "Metric": "10",
        "Data": "192.168.100.26"
      },
      {
        "Link ID": "192.168.100.25",
        "Link Type": "StubNet",
        "Metric": "10",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      },
      {
        "Link ID": "1.1.1.2",
        "Link Type": "P-2-P",
        "Metric": "10",
        "Data": "192.168.100.54"
      },
      {
        "Link ID": "192.168.100.53",
        "Link Type": "StubNet",
        "Metric": "10",
        "Data": "255.255.255.255",
        "Priority": "Medium"
      }
    ],
    "Len": "96",
    "Ls id": "1.1.1.1",
    "chksum": "0x16fc",
    "Adv rtr": "1.1.1.1",
    "Type": "Router",
    "Options": "ASBR  E",
    "Link count": "6"
  }
]
'''
input_lst = json.loads(s)
myresult=[]
for item in input_lst:
    mydict={}
    mydict_sID = item['Ls id']
    mydict_type = item['Type']
    temp = []
    for x in item['items']:
        mydict={'Ls id': mydict_sID,
                'Type': mydict_type,
                'Link ID': x['Link ID'],
                'Metric': x['Metric'],
                'Link Type': x['Link Type']
                }
        temp.append(mydict)
    myresult.extend(temp)

确保根据需要更改我用来读取字符串的代码行。

【讨论】：

感谢先生为我提供指导和对代码的更改。再次感谢您。

【解决方案4】：

问题在于item['items'] 也是一个列表，因此您需要一个内部循环来处理其所有元素。此外，您必须单独提取每个值：

for item in json_decode:
    for sub in item.get('items'):
        mydict={}
        mydict['type']=item.get('Type')
        mydict['sID']=item.get('Ls id')
        mydict['dID']=sub.get('Link ID')
        mydict['Link Type']=sub.get('Link Type')
        mydict['Metric']=sub.get('Metric')
        myresult.append(mydict)

【讨论】：

【解决方案5】：

要处理列表的嵌套对象的元素，需要使用额外的循环，例如，

import json

ifile = 'source.json'
ofile = 'extract.json'

myresult = []
with open(ifile, 'r') as sf:
   json_decode = json.load(sf)
   for item in json_decode:
       for sub_item in item.get('items', []):
           myresult.append(dict(type=item.get('Type'),
                                sID=item.get('Ls id', ''),
                                dID=sub_item.get('Link ID'),
                                LinkType=sub_item.get('Link Type'),
                                Metric=sub_item.get('Metric')
                                )
                           )

with open(ofile, 'w') as of:
    of.write(json.dumps(myresult, indent=4))

或使用列表推导的稍微缩写的版本：

import json

ifile = 'source.json'
ofile = 'extract.json'

with open(ifile, 'r') as sf:
    json_decode = json.load(sf)
    myresult = [dict(type=item.get('Type'), 
                     sID=item.get('Ls id', ''), 
                     dID=sub_item.get('Link ID'),
                     LinkType=sub_item.get('Link Type'), 
                     Metric=sub_item.get('Metric')) for item in json_decode 
                for sub_item in item.get('items', [])]

with open(ofile, 'w') as of:
    of.write(json.dumps(myresult, indent=4))

【讨论】：

谢谢先生。对于我的情况，两者都是一个很好的解决方案，并且确实有效。感谢分享，我很感激。