使用lodash按键对数组中的对象进行排序

Question

嗨Stack Overflow社区！

我有以下测试数组：

let test = [{
    "searchQuery": "test",
    "resultsLoaded": -1,
    "offset": -1,
    "allResults": 10
}, {
    "metaData": {
        "type": "page-content",
        "image": true,
        "name": "lorem-ipsum",
        "rank": 10,
        "tags": ["website:lorem/ipsum"]
    },
    "componentData": {
        "header": "Lorem Ipsum",
        "path": "/content/asdf",
        "breadcrumbDouble": {
            "breadcrumbItem1": {
                "href": "lorem ipsum",
                "text": "lorem ipsum"
            },
            "breadcrumbItem2": {
                "href": "/content/asdf",
                "text": "Lorem Ipsum"
            }
        },
        "content": {
            "subheadline": "Lorem Ipsum",
            "img": {
                "alt": "",
                "imgSrc": "/content/dam/production/images/asdf.jpeg.imgTransformer/listPageItem/desktop/1511962617778/asdf.jpg"
            },
            "tags": [{
                "category": "lorem",
                "value": "ipsum"
            }]
        }
    }
}, {
    "metaData": {
        "type": "page-content",
        "image": true,
        "name": "lorem-ipsum",
        "rank": 50,
        "tags": ["website:lorem/ipsum"]
    },
    "componentData": {
        "header": "Lorem Ipsum",
        "path": "/content/asdf",
        "breadcrumbDouble": {
            "breadcrumbItem1": {
                "href": "lorem ipsum",
                "text": "lorem ipsum"
            },
            "breadcrumbItem2": {
                "href": "/content/asdf",
                "text": "Lorem Ipsum"
            }
        },
        "content": {
            "subheadline": "Lorem Ipsum",
            "img": {
                "alt": "",
                "imgSrc": "/content/dam/production/images/asdf.jpeg.imgTransformer/listPageItem/desktop/1511962617778/asdf.jpg"
            },
            "tags": [{
                "category": "lorem",
                "value": "ipsum"
            }]
        }
    }
}, {
    "metaData": {
        "type": "page-content",
        "image": true,
        "name": "lorem-ipsum",
        "rank": 30,
        "tags": ["website:lorem/ipsum"]
    },
    "componentData": {
        "header": "Lorem Ipsum",
        "path": "/content/asdf",
        "breadcrumbDouble": {
            "breadcrumbItem1": {
                "href": "lorem ipsum",
                "text": "lorem ipsum"
            },
            "breadcrumbItem2": {
                "href": "/content/asdf",
                "text": "Lorem Ipsum"
            }
        },
        "content": {
            "subheadline": "Lorem Ipsum",
            "img": {
                "alt": "",
                "imgSrc": "/content/dam/production/images/asdf.jpeg.imgTransformer/listPageItem/desktop/1511962617778/asdf.jpg"
            },
            "tags": [{
                "category": "lorem",
                "value": "ipsum"
            }]
        }
    }
}];

我现在想要的是按metaData.rank从最高到最低排序对象。

我想像这样使用lodash的orderBy() ：

let result = orderBy(test, function(e) {
    let array = parseInt(e.metaData.rank);
    return array;
}, ['desc']);

但是我收到以下错误：

TypeError：无法读取未定义的属性“rank”

我的orderBy函数中的console.log(e)显示了这个：

{
    searchQuery: 'test',
    resultsLoaded: -1,
    offset: -1,
    allResults: 10
}

有任何快速建议来解决这个问题

我知道第一个对象是因为结构不同而导致问题。 所以我需要解决它！

Answer 1

数组中的第一个元素，

{
    "searchQuery": "test",
    "resultsLoaded": -1,
    "offset": -1,
    "allResults": 10
}

， 没有属性metaData ，并且由于还没有rank通过对它进行排序。

---

您可能希望在排序之前将其从数组中删除，或者将其视为身份函数中的特殊情况，例如：

function(e) {
    return !e.metaData
        ? -1
        : parseInt(e.metaData.rank);
}

Answer 2

您可以将没有metaData属性的项目移动到顶部，并按rank对其余项目进行rank 。

 var array = [{ searchQuery: "test", resultsLoaded: -1, offset: -1, allResults: 10 }, { metaData: { type: "page-content", image: true, name: "lorem-ipsum", rank: 10, tags: ["website:lorem/ipsum"] }, componentData: { header: "Lorem Ipsum", path: "/content/asdf", breadcrumbDouble: { breadcrumbItem1: { href: "lorem ipsum", text: "lorem ipsum" }, breadcrumbItem2: { href: "/content/asdf", text: "Lorem Ipsum" } }, content: { subheadline: "Lorem Ipsum", img: { alt: "", imgSrc: "/content/dam/production/images/asdf.jpeg.imgTransformer/listPageItem/desktop/1511962617778/asdf.jpg" }, tags: [{ category: "lorem", value: "ipsum" }] } } }, { metaData: { type: "page-content", image: true, name: "lorem-ipsum", rank: 50, tags: ["website:lorem/ipsum"] }, componentData: { header: "Lorem Ipsum", path: "/content/asdf", breadcrumbDouble: { breadcrumbItem1: { href: "lorem ipsum", text: "lorem ipsum" }, breadcrumbItem2: { href: "/content/asdf", text: "Lorem Ipsum" } }, content: { subheadline: "Lorem Ipsum", img: { alt: "", imgSrc: "/content/dam/production/images/asdf.jpeg.imgTransformer/listPageItem/desktop/1511962617778/asdf.jpg" }, tags: [{ category: "lorem", value: "ipsum" }] } } }, { metaData: { type: "page-content", image: true, name: "lorem-ipsum", rank: 30, tags: ["website:lorem/ipsum"] }, componentData: { header: "Lorem Ipsum", path: "/content/asdf", breadcrumbDouble: { breadcrumbItem1: { href: "lorem ipsum", text: "lorem ipsum" }, breadcrumbItem2: { href: "/content/asdf", text: "Lorem Ipsum" } }, content: { subheadline: "Lorem Ipsum", img: { alt: "", imgSrc: "/content/dam/production/images/asdf.jpeg.imgTransformer/listPageItem/desktop/1511962617778/asdf.jpg" }, tags: [{ category: "lorem", value: "ipsum" }] } } }]; array.sort(function (a, b) { return ('metaData' in a) - ('metaData' in b) || b.metaData.rank - a.metaData.rank; }); console.log(array); 

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

Answer 3

数组test的第一个对象导致了该问题。 它与其他结构的结构不同。 如果e是第一个对象，那么e.metaData是undefined 。

我建议你shift是第一个对象， sort数组，然后unshift回数组排序：

let test = [...];

let first = test.shift();                                  // remove the first object from the array and store it in 'first'
test.sort((a, b) => b.metaData.rank - a.metaData.rank);    // sort the array (you can use orderBy here if you want)
test.unshift(first);                                       // unshift the first object (return it back to the first index of the array)

注意：我建议的解决方案假设只有一个不同的对象，并且该对象始终位于索引0 。

Answer 4

相反， e.metaData.rank使用：

_.get(e, ['metaData', 'rank'], /*value if rank field is not exist*/ -1);