如何从一组复杂的对象中获取一组唯一的属性

Question

我有一个类似于的对象数组

const array = [
{
    documentId: "document1",
    writers: [
        {
            name: "writer1", 
            date: "2017-12-11"
        },
        {
            name: "writer2", 
            date: "2017-12-11"
        }
    ]
},
{
    documentId: "document2",
    writers: [
        {
            name: "writer1", 
            date: "2017-12-11"
        },
        {
            name: "writer3", 
            date: "2017-12-11"
        }
    ]
},
{
    documentId: "document3",
    writers: [
        {
            name: "writer3", 
            date: "2017-12-11"
        },
        {
            name: "writer4", 
            date: "2017-12-11"
        }
    ]
},

我正在尝试提取所有唯一作者的姓名，并将其与他们编写的所有文档匹配，以使最终数组看起来像这样：

const finalArray = [
    {name: "writter1", documents: ["document1", "document2"]},
    {name: "writter2", documents: ["document1"]},
    {name: "writter3", documents: ["document2", "document3"]},
    {name: "writter4", documents: ["document3"]}
]

Answer 1

您可以使用Map将writer保留为键，然后在数组上调用reduce将文档映射到writer，然后在Map对象上调用values() ：

const ret = Array.from(array.reduce((acc, val) => {
  val.writers.forEach(({ name }) => {
    let w = acc.get(name) || { name: name, documents: [] };
    w.documents = w.documents.concat(val.documentId);
    acc.set(name, w);
  });
  return acc;
}, new Map()).values());

console.log(ret);

Answer 2

您可以选择一个包含所有名称和相关文档的Map 。 如果没有可用的名称映射，则创建一个新条目。

然后结束，获取地图的所有对象。

 var array = [{ documentId: "document1", writers: [{ name: "writer1", date: "2017-12-11" }, { name: "writer2", date: "2017-12-11" }] }, { documentId: "document2", writers: [{ name: "writer1", date: "2017-12-11" }, { name: "writer3", date: "2017-12-11" }] }, { documentId: "document3", writers: [{ name: "writer3", date: "2017-12-11" }, { name: "writer4", date: "2017-12-11" }] }], map = new Map, result; array.forEach(function (o) { o.writers.forEach(function ({ name }) { map.has(name) || map.set(name, { name, documents: [] }); map.get(name).documents.push(o.documentId); }); }); result = Array.from(map.values()); console.log(result); 

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Answer 3

也许会有一个更优雅的map-reduce解决方案。 无论如何，即使它很丑，它也可以工作：

const array = //your data
var output = []
for (let i = 0; i < array.length; i++)
    for (let k = 0; k < array[i].writers.length; k++) {
        let t = output.find(function(a){return array[i].writers[k].name === a.name})
        if (t)
            t.documents.push(array[i].documentId)
        else
            output.push({name: array[i].writers[k].name, documents: [array[i].documentId]})
  }
console.log(output)

https://jsfiddle.net/50oph5g4/1/