有條件地合并物件陣列

我正在尋找一種優雅的方式（最好是不可變的，lodash - 好的）來有條件地壓縮陣列。我想檢查section和path值組合的重復項，并附加ids這些重復項。所以給定

const arrayToBeCompacted = [
  {
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id1"]
  },
  {
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id2"]
  },
  {
    section: "Section name2",
    path: ["segment1", "segment2"],
    ids: ["id3"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id4"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id5"]
  },
]

結果我想

const resultingArray = [
  {
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id1", "id2"]
  },
  {
    section: "Section name 2",
    path: ["segment1", "segment2"],
    ids: ["id3"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id4", "id5"]
  },
]

似乎這并不是我想要的lodash.uniq(By, With)。lodash.union(By, With)

uj5u.com熱心網友回復：

你可以用減少來做到這一點

const arrayToBeCompacted = [
  {
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id1"]
  },
  {
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id2"]
  },
  {
    section: "Section name2",
    path: ["segment1", "segment2"],
    ids: ["id3"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id4"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id5"]
  },
]

const compacted = Object.values(arrayToBeCompacted.reduce((res, {section, path, ids}) => {
  const key = section   path.join('|')
  const existing = res[key] || {ids: [], section, path}
  existing.ids = [...existing.ids, ...ids]
  res[key] = existing
  return res

}, {}))

console.log(compacted)

uj5u.com熱心網友回復：

以下是實作目標的一種可能方式。

代碼片段

// method to compact array of objects
const compactArr = arr => (
  Object.values(      // extract values from intermediate result-obj
    arr.reduce(       // iterate over the array using "reduce"
      (acc, itm) => {         // "acc" is the accumuator/aggregator
        const {section, ids, path} = itm;     // de-structure to get props
        // construct uniq-key using "section" and "path"
        const uniqKey = `${section}-${path.join('-')}`;
        acc[uniqKey] = {
          ...(acc[uniqKey] || {}),
          section, path,              // if "section" already exists, concat "ids"
          ids: (acc[uniqKey]?.ids ?? []).concat(ids)
        }
        return acc;
      },
      {}            // initial value of "acc" is empty-object {}
    )
  )                 // implicit return from method
);

const arrayToBeCompacted = [{
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id1"]
  },
  {
    section: "Section name 1",
    path: ["segment1", "segment2"],
    ids: ["id2"]
  },
  {
    section: "Section name2",
    path: ["segment1", "segment2"],
    ids: ["id3"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id4"]
  },
  {
    section: "Another section",
    path: ["segment1", "segment2"],
    ids: ["id5"]
  },
];

console.log('compacted array: ', compactArr(arrayToBeCompacted));

.as-console-wrapper { max-height: 100% !important; top: 0 }

解釋

在上面的代碼段中添加了行內注釋。

標籤：javascript 罗达什

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