NEXT_OFFSET条数组记录

Question

我尝试获取元素数组并使用以下代码获取数组：

 const result = payload.map(({QUALITY, TEMPERATURE, SENSOR_READING_DATETIME, SOURCE_COMPONENT_ID, SENSOR_NAME, NEXT_OFFSET})=> ({
        TELEMATICS: {
          QUALITY,
          TEMPERATURE
        },
      SOURCE_COMPONENT_ID,
      SENSOR_NAME,
      SENSOR_READING_DATETIME,
      NEXT_OFFSET
    }));

结果看起来像这样：

{
    data": [
            {
                "TELEMATICS": {
                    "QUALITY": 91.98,
                    "TEMPERATURE": 20.5
                },
                "id": 118,
                "SENSOR_READING_DATETIME": "2021-09-24T04:53:06.801Z",
                "SOURCE_COMPONENT_ID": 1,
                "SENSOR_NAME": "TD2",
                "NEXT_OFFSET": 119
            }
            ,
            {
                "TELEMATICS": {
                    "QUALITY": 91.98,
                    "TEMPERATURE": 20.5
                },
                "id": 119,
                "SENSOR_READING_DATETIME": "2021-09-24T05:53:09.774Z",
                "SOURCE_COMPONENT_ID": 1,
                "SENSOR_NAME": "TD2",
                "NEXT_OFFSET": 120
            }
           ]
    }

但我试图获取元素之外的 NEXT_OFFSET，并且仅获取数组的最后一条记录。

它必须看起来像这个例子：

{
    data": [
            {
                "TELEMATICS": {
                    "QUALITY": 91.98,
                    "TEMPERATURE": 20.5
                },
                "id": 118,
                "SENSOR_READING_DATETIME": "2021-09-24T04:53:06.801Z",
                "SOURCE_COMPONENT_ID": 1,
                "SENSOR_NAME": "TD2"
            }
            ,
            {
                "TELEMATICS": {
                    "QUALITY": 91.98,
                    "TEMPERATURE": 20.5
                },
                "id": 119,
                "SENSOR_READING_DATETIME": "2021-09-24T05:53:09.774Z",
                "SOURCE_COMPONENT_ID": 1,
                "SENSOR_NAME": "TD2"
            }
           ]
        "NEXT_OFFSET": 120
    }

我怎样才能做到，就像示例中那样？

Answer 1

您可以使用 Array.reduce 来累积您的结果并在您点击最后一项时添加额外的字段。如果您将额外属性的初始值设置为 null，它也会处理您的 'no results' 案例。

简化版是这样的：

const payload = [
  { a: 1, b: 2 },
  { a: 5, b: 6 },
  { a: 10, b: 11 }
];

const res = payload.reduce(
  (acc, { a, b }, index) =>
    index === payload.length - 1
      ? { ...acc, data: [...acc.data, a],b }
      : { ...acc, data: [...acc.data, a] },

  { data: [], b:null }
);

console.log(res);

对于您的示例，如果您要批量获取 REQUEST_COUNT 项（例如 2000），它可能看起来像这样：

const res = payload.reduce(
  (acc, { NEXT_OFFSET, ...item }, index) => {
    const data = [...acc.data, item];
    if (index < payload.length - 1) {
      return { data };
    } else {
      const nextOffset =
        payload.length < REQUEST_COUNT
          ? { NEXT_OFFSET: null }
          : { NEXT_OFFSET 
       return {data, ...nextOffset}
    }
  },
  { data: [], NEXT_OFFSET: null }
);

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