Jolt - 从数组中删除最后一个元素

Question

经过一些颠簸的转变和默认操作后，我剩下

"items" : [ null, "-70.7", "-70.4", "-68.5", null, "tmp" ]


 

我想要实现的最后一件事是从数组中删除这个“tmp”字符串。

有什么实现方法吗？我已经尝试过不同的方法但没有结果：/

Answer 1

您可以使用 shift 转换，通过 pipe[=最后一个元素 以外的数组索引组合pipe(|) 运算符如

[
  {
    "operation": "shift",
    "spec": {
      "items": {
        "0|1|2|3|4": {
          "@": "&2.[&1]"
        }
      }
    }
  }
]

http://jolt-demo.appspot.com/ 上的演示：

动态解决方案可能是连续变换，也可以通过添加 修改 变换。

在下面的规范中执行从 null 到 "null" 的额外转换以应用该技术交换键和值对以防止 null 值的灭绝问题，例如

[
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "items": ["=toString", "null"],
      "sz_items": "=size(@(1,items))",
      "sz_items_minus_1": "=intSum(-1,@(1,sz_items))"
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": "&"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "$": "[&].@(0)"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": {
          "$": "items[@(0)]"
        }
      }
    }
  }
]

演示：

或更动态的解决方案，甚至 keeping null 值也可能是

[
  //determine the length of the lists(arrays) except for the rightmost element
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "sz_items": "=size(@(1,items))",
      "sz_items_minus_1": "=intSum(-1,@(1,sz_items))"
    }
  },
  //get rid of unnecessary attribute
  {
    "operation": "remove",
    "spec": {
      "sz_items": ""
    }
  },
  //determine the rightmost element as a list
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": "items.&"
      },
      "@": "xxx"
    }
  },
  //convert the values of the elements of the "items" to lists 
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "items": {
        "*": "=toList(@(1,&))"
      }
    }
  },
  //determine the length of the elements of the "items" to lists 
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "items": {
        "*": ["=size(@(1,&))", 0]
      }
    }
  },
  //filter out generated elements with multiple component(eg. keep 0 or 1)
  //in order to reform the list
  {
    "operation": "shift",
    "spec": {
      "xxx": {
        "items": {
          "*": {
            "@(3,&1.&)": {
              "0|1": { "@2": "&4[&3]" }
            }
          }
        }
      }
    }
  }
]