如何对具有动态属性的数组进行排序？ [复制]

Posted 2023-02-22

【中文标题】如何对具有动态属性的数组进行排序？ [复制]

【英文标题】：How to sort an array with dynamic property? [duplicate]

【发布时间】：2019-04-06 07:27:29

【问题描述】：

我有一组电影，我试图根据标记为“路径”的动态值进行排序，该值根据当前的情况评估为“标题”、“流派名称”、“编号InStock”或“每日租借率”状态。然而，因为电影数组中的“流派”属性是一个对象，而不是像其他的字符串，所以我编写的比较函数试图访问movieA（“genre.name”）和movieB（“genre.name”）。我认为这种语法可能有效，但它没有。当然，必须有一种优雅的方式来编写我的比较函数，而不需要在路径设置为“genre.name”时添加更多条件？非常感谢任何帮助或见解。谢谢。（下面是一些代码 sn-ps）

var movies = [
    
        title: "Terminator",
        genre:  _id: "5b21ca3eeb7f6fbccd471818", name: "Action" ,
        numberInStock: 6,
        dailyRentalRate: 2.5,
    ,
    
        title: "Die Hard",
        genre:  _id: "5b21ca3eeb7f6fbccd471818", name: "Action" ,
        numberInStock: 5,
        dailyRentalRate: 2.5
    ,
    
        title: "Get Out",
        genre:  _id: "5b21ca3eeb7f6fbccd471820", name: "Thriller" ,
        numberInStock: 8,
        dailyRentalRate: 3.5
    
]

this.state = 
    path: "title"  //'title' or 'genre.name' or 'numberInStock' or 'dailyRentalRate'
;

myCompare = (a, b) => 
    const path  = this.state.path;

    if (a[path] < b[path]) return - 1;
    if (a[path] > b[path]) return 1;
    return 0;


const moviesSorted = movies.sort(this.myCompare);

【参考方案1】：

当路径包含句点时，您应该将其转换为带有split 的数组，然后使用reduce 对其进行迭代并找到您尝试排序的嵌套值：

var movies = [
    
        title: "foo bar",
        genre:  _id: "5b21ca3eeb7f6fbccd471820", name: "Thriller" ,
        numberInStock: 8,
        dailyRentalRate: 3
    ,
    
        title: "Terminator",
        genre:  _id: "5b21ca3eeb7f6fbccd471818", name: "Action" ,
        numberInStock: 6,
        dailyRentalRate: 2.5,
    ,
    
        title: "Die Hard",
        genre:  _id: "5b21ca3eeb7f6fbccd471818", name: "Action" ,
        numberInStock: 5,
        dailyRentalRate: 2
    ,
    
        title: "Get Out",
        genre:  _id: "5b21ca3eeb7f6fbccd471820", name: "Thriller" ,
        numberInStock: 8,
        dailyRentalRate: 3.5
    
];

let path = "title";

const getNested = (obj, path) => path.split('.').reduce((a, prop) => a[prop], obj);
const myCompare = (a, b) => 
  const aVal = getNested(a, path);
  return typeof aVal === 'string'
  ? aVal.localeCompare(getNested(b, path))
  : aVal - getNested(b, path);
;

// Sort by title:
movies.sort(myCompare);
console.log(movies);

// Sort by genre.name:
path = 'genre.name';
movies.sort(myCompare);
console.log(movies);

【参考方案2】：

或许，您可以编写一个辅助函数来获取嵌套值，如下所示：

function getNestedValue(fieldName, item) 
    if (fieldName.includes('.')) 
        const keyArr = fieldName.split('.');
        let result = item;
        if (keyArr.length > 1) 
            for (const key of keyArr) 
                result = result[key];
            

            return result;
        
    

    return item[fieldName];


myCompare = (a, b) => 
    const  path  = this.state.sortColumn;
    const valueA = getNestedValue(path, a);
    const valueB = getNestedValue(path, b)

    if (valueA < valueB) return - 1;
    if valueA > valueB) return 1;
    return 0;

并比较给定的结果。