从 Kafka 消息中读取的 Json 路径

Question

我有一条如下所示的 kafka 消息，我试图从 json 路径中读取数据。但是，在从 json 路径读取某些属性时，我遇到了挑战。这是示例消息。

样本1：

{
  "header": {
    "bu": "google",
    "id": "12345",
    "bum": "google",
    "originTimestamp": "2021-10-09T15:17:09.842+00:00",
    "batchSize": "0",
    "jobType": "Batch"
  },
  "payload": {
    "derivationdetails": {
      "Id": "6783jhvvh897u31y283y",
      "itemid": "1234567",
      "batchid": 107,
      "attributes": {
        "itemid": "1234567",
        "lineNbr": "1498",
        "cat": "5929",
        "Id": "6783jhvvh897u31y283y",
        "indicator": "false",
        "subcat": "3514"
      },
      "Exception": {
        "values": [
          {
            "type": "PICK",
            "value": "blocked",
            "Reason": [
              "RULE"
            ],
            "rules": [
              "439"
            ]
          }
        ],
        "rulesBagInfo": [
          {
            "Idtype": "XXXX",
            "uniqueid": "7889423rbhevfhjaufdyeuiryeukjbdafvjd",
            "rulesMatch": [
              "439"
            ]
          }
        ]
      }
    }
  }
}

示例 2：相同的消息，但看到“有效负载”的差异

{
  "header": {
    "bu": "google",
    "id": "12345",
    "bum": "google",
    "originTimestamp": "2021-10-09T15:17:09.842+00:00",
    "batchSize": "0",
    "jobType": "Batch"
  },
  "payload": {
      "Id": "6783jhvvh897u31y283y",
      "itemid": "1234567",
      "batchid": 107,
      "attributes": {
        "itemid": "1234567",
        "lineNbr": "1498",
        "cat": "5929",
        "Id": "6783jhvvh897u31y283y",
        "indicator": "false",
        "subcat": "3514"
      },
      "Exception": {
        "values": [
          {
            "type": "PICK",
            "value": "blocked",
            "Reason": [
              "RULE"
            ],
            "rules": [
              "439"
            ]
          }
        ],
        "rulesBagInfo": [
          {
            "Idtype": "XXXX",
            "uniqueid": "7889423rbhevfhjaufdyeuiryeukjbdafvjd",
            "rulesMatch": [
              "439"
            ]
          }
        ]
      }
  }
}

如果您观察到，有时消息包含“派生详细信息”，有时则没有。但不管它是否存在，我都需要读取 id、itemid 和 batchid 的值。我尝试使用

$.payload[*].id
$.payload[*].itemid
$.payload[*].batchid

但我看到，对于 batchid，即使它在消息中有一个值，它也会返回 null，如果我使用上述内容，“属性”下的属性会返回 null。对于使用此（示例）的“属性”下的字段：

$.payload.attributes.itemId

而且，对于如何阅读以下部分完全空白。

"Exception": {
        "values": [
          {
            "type": "PICK",
            "value": "blocked",
            "Reason": [
              "RULE"
            ],
            "rules": [
              "439"
            ]
          }
        ],
        "rulesBagInfo": [
          {
            "Idtype": "XXXX",
            "uniqueid": "7889423rbhevfhjaufdyeuiryeukjbdafvjd",
            "rulesMatch": [
              "439"
            ]

我是新手，需要一些关于如何正确读取属性的建议。任何帮助将不胜感激。谢谢

Answer 1

使用..(递归下降，深度扫描。JSONPath 借用了 E4X 的这种语法。) 来获取值。但是如果有多个具有相同键的条目嵌套在深处，它将返回一个列表。

jsonpath 下方的表达式将返回一个 list，其中 sample1 和 sample2 各有一项

$.payload..attributes.Id
$.payload..attributes.itemid
$.payload..batchid
$.payload..Exception