从json中选择键并在python中创建csv文件

Question

我有一个JSON文件，里面有多个键和值对。我用我想要的特定键创建干净的JSON文件，最后将其转换成csv格式。你知道吗

**这是我想要一些选定键值的JSON文件**

{
  "sessions": [
    {
      "message": {
        "type": 4,
        "offset": 157485,
        "screenviewOffset": 157482,
        "count": 9,
        "fromWeb": true,
        "target": {
          "id": "txtUsername",
          "idType": -1,
          "name": "txtUsername",
          "tlType": "textBox",
          "type": "input",
          "position": {
            "width": 252,
            "height": 16
          },
          "currState": {
            "value": "Admin"
          },
          "subType": "text",
          "isParentLink": false,
          "prevState": {
            "value": ""
          },
          "visitedCount": 1,
          "dwell": 4
        },
        "event": {
          "tlEvent": "valueChange",
          "type": "change"
        },
        "dcid": "dcid-2.1568976636434",
        "focusInOffset": 157480
      }
    }
  ]
}

**我这样试过**

T_tlType = data['sessions'][0]['message']['target']['tlType']
T_type = data['sessions'][0]['message']['target']['type']
T_subType = data['sessions'][0]['message']['target']['subType']

# value that was put by user

CS_index = data['sessions'][0]['message']['target']['currState']['index']
CS_text = data['sessions'][0]['message']['target']['currState']['text']
CS_value = data['sessions'][0]['message']['target']['currState']['value']

但是当我传递一个json文件时，它没有一个我在这里调用的特定键，那么它就给了我一个错误

CS_index = data['sessions'][0]['message']['target']['currState']['index'] KeyError: 'index'