JOLT 仅从数组中的数组中获取一个值答案

【问题标题】：JOLT get only one value from an array inside an arrayJOLT 仅从数组中的数组中获取一个值
【发布时间】：2021-07-22 15:48:08
【问题描述】：

我一直试图弄清楚如何从这个 JSON 中的事件数组中的数组中获取第一个值。

我认为我必须对 Cardinality 做一些事情，但我无法完全弄清楚，因此我们将不胜感激。

这就是我的 JSON 的样子

{
  "rootid": "19718",
  "clloadm": "2021-06-01T22:40:02",
  "clload": "2021-06-01T21:21:39",
  "date": "2021-05-25T21:52:30",
  "events": [
    {
      "done": {
        "id": "e0",
        "value": "2021-05-29T08:08:19"
      },
      "id": "e0_event",
      "started": {
        "id": "e0",
        "value": "2021-05-29T08:08:19"
      },
      "status": "complete"
    },
    {
      "done": {
        "id": "e1",
        "value": "2021-05-27T02:20:25"
      },
      "id": "e1_event",
      "started": {
        "id": "e1",
        "value": "2021-05-27T02:20:25"
      },
      "status": "complete"
    },
    {
      "done": {
        "id": "e2",
        "value": "2021-05-29T08:08:19"
      },
      "id": "e2_event",
      "started": {
        "id": "e2",
        "value": "2021-05-29T08:08:19"
      },
      "status": "complete"
    },
    {
      "done": {
        "id": "e3",
        "value": "2021-05-29T08:08:19"
      },
      "id": "e3_event",
      "started": {
        "id": "e3",
        "value": "2021-05-29T08:08:19"
      },
      "status": "complete"
    },
    {
      "done": {
        "id": "e4",
        "value": "2021-05-29T08:08:19"
      },
      "id": "e4_event",
      "started": {
        "id": "e4",
        "value": "2021-05-29T08:08:19"
      },
      "status": "complete"
    }
  ],
  "ids": [
    {
      "id": "id",
      "source": "source",
      "value": "value"
    }
  ]
}

我的 Jolt 规格

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

我得到的结果：

{
  "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", "2021-05-29T08:08:19" ],
  "id" : "value",
  "new_id" : "value"
}

我希望结果更像这样，只选择第一个值：

{
  "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",
  "e4" : "2021-05-29T08:08:19",
  "id" : "value",
  "new_id" : "value"
}

编辑：我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。

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

【问题讨论】：

标签： json jolt

【解决方案1】：

是的，您只需添加一个基数转换，例如

{
  "operation": "cardinality",
  "spec": {
    "*": "ONE"
  }
}

或可选地使用 e* 通配符来限制具有以字母 e 开头的键的数组的结果，例如

{
  "operation": "cardinality",
  "spec": {
    "e*": "ONE"
  }
}

编辑：只需要添加到当前规范。因此，您可以使用以下内容：

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

【讨论】：

您好，感谢您的回答，但不幸的是，我似乎无法弄清楚如何将该转换添加到我的规范中。请查看我的编辑，我尝试将其合并，但仍然没有得到答案。