猫鼬数组不会排序

Question

一个 mongodb 文档包含一个数组。当使用 mongoose 和 graphql 检索到前端时，对数组使用 .sort() 会引发错误。

无法分配给对象“[object Array]”的只读属性“1”

但是，在完全相同的数组（但这次是硬编码）上使用 .sort() 是可行的。

这里发生了什么？！

const c = [ { slug: 'first-element',
    position: 1,
    alphaPos: 'B',
    type: 'heading',
    data: 'first-el B' },
{ slug: 'second-element',
    position: 2,
    alphaPos: 'C',
    type: 'textarea',
    data: 'second-el C' },
{ slug: 'third-element',
    position: 3,
    alphaPos: 'A',
    type: 'textarea',
    data: 'third-el A' },
{ slug: 'third-b-element',
    position: 3,
    alphaPos: 'D',
    type: 'textarea',
    data: 'third-el-22222 D' } ]

    // 'content' is the same as 'c' but it comes from mongoose, 
    // it throws an error
    console.log('content ==', content.sort())

    // 'c' is hard coded, no error is thrown
    console.log('content ==', c.sort())

    // console.log(c) and console.log(content) output exactly the same  array

[编辑：这是 mongo 文档]

    {
        "_id" : ObjectId("5a801422f1c5437466c5d285"),
        "createdAt" : ISODate("2018-02-11T10:00:02.800Z"),
        "id" : 1,
        "slug" : "interesting-story",
        "creatorId" : 3,
        "title" : "An interesting story",
        "image" : "/images/image1.jpg",
        "description" : "description",
        "content" : [ 
            {
                "slug" : "first-element",
                "position" : 1,
                "alphaPos" : "B",
                "type" : "heading",
                "data" : "first-el B"
            }, 
            {
                "slug" : "second-element",
                "position" : 2,
                "alphaPos" : "C",
                "type" : "textarea",
                "data" : "second-el C"
            }, 
            {
                "slug" : "third-element",
                "position" : 3,
                "alphaPos" : "A",
                "type" : "textarea",
                "data" : "third-el A"
            }, 
            {
                "slug" : "third-b-element",
                "position" : 3,
                "alphaPos" : "D",
                "type" : "textarea",
                "data" : "third-el-22222 D"
            }
        ],
        "__v" : 0
    }

这是架构

const postSchema = new Schema({
    id: { type: Number, required: true, unique: true },
    slug: { type: String, required: true, unique: true },
    creatorId: { type: Number, required: true },
    title: { type: String, required: true },
    image: { type: String, required: false },
    description: { type: String, required: true },
    content: { type: Array, required: false },
    createdAt: { type: Date, default: Date.now },
})

Answer 1

如果有人遇到同样的错误，我仍然无法解释，但数组被认为是一个以索引为键的对象......

如果有人对此行为有解释（与 graphql 相关？与 mongoose 相关？可能与 graphql-type-json 包相关？），我会很感兴趣。

所以要对其进行排序，这就是我正在做的事情（输出一个数组）。

Object.keys(content).sort(a=>1).reduce((_sortedObj, key) => {
    _sortedObj.push(content[key])
    return _sortedObj
    }, [])

Answer 2

因为它们是 2 种不同的排序，取决于您所说的排序。如果你在数组（“硬编码”）上调用它，它使用默认排序函数https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort，如果你不能在不编写排序函数的情况下在 mongodocument 对象类型上调用它。

要使用猫鼬排序，您必须在构建查询时应用它

collection.find().sort().then(...)