我一直在试图弄清楚如何从这个 JSON 的事件数组中的数组中获取第一个值。

我想我必须对 Cardinality 做一些事情，但我无法弄清楚，因此我们将不胜感激。

这就是我的 JSON 的样子

[
  {
    "operation": "shift","spec": {
      "*": "&","events": {
        "*": {
          "*": {
            "@id": {
              "e0": { "@(2,value)": "&" },"e4": { "@(2,value)": "&" }
            }
          }
        }
      },"ids": {
        "*": {
          "@value": "@id"
        }
      }
    }
  }
]

我的 Jolt 规格

{
  "rootid" : "19718","clloadm" : "2021-06-01T22:40:02","clload" : "2021-06-01T21:21:39","date" : "2021-05-25T21:52:30","e0" : [ "2021-05-29T08:08:19","2021-05-29T08:08:19" ],"e4" : [ "2021-05-29T08:08:19","id" : "value","new_id" : "value"
}

我得到的结果：

{
  "rootid" : "19718","e0" : "2021-05-29T08:08:19","e4" : "2021-05-29T08:08:19","new_id" : "value"
}

我希望结果更像这样，只选择第一个值：

[
  {
    "operation": "shift","e4": {
                "operation": "cardinality","spec": {
                  "e4": "ONE"
                }
              }
            }
          }
        }
      },"ids": {
        "*": {
          "@value": "@id"
        }
      }
    }
  }
]

编辑： 我已经尝试将基数添加到我的规范中，但我似乎无法得到我想要的结果。

## Assuming that the target data is always under sections[i].payload
from json import loads
line = open("data.json").read()
data = loads(line)["sections"]
for x in data:
    try:
        # With assumption that there is only one payload
        if x["payload"][0]["url"]:
            print(x["payload"][0]["url"])
    except KeyError:
        pass