Lodash在嵌套数组中选择 [英] lodash pick in nested array

问题描述

我有一个这样的对象数组:

I have an array of objects like this:

{
  "sizes":{
     "thumbnail":{
        "height":300,
        "width":300,
        "url":"http://example.com/wp-content/uploads/2017/04/web-300x300.jpg",
        "orientation":"landscape"
     },
     "medium":{
        "height":267,
        "width":400,
        "url":"http://example.com/wp-content/uploads/2017/04/web-400x267.jpg",
        "orientation":"landscape"
     },
     "large":{
        "height":441,
        "width":660,
        "url":"http://example.com/wp-content/uploads/2017/04/web-1024x684.jpg",
        "orientation":"landscape"
     },
     "full":{
        "url":"http://example.com/wp-content/uploads/2017/04/web.jpg",
        "height":1200,
        "width":1796,
        "orientation":"landscape"
     }
  },
  "mime":"image/jpeg",
  "type":"image",
  "subtype":"jpeg",
  "id":3589,
  "url":"http://example.com/wp-content/uploads/2017/04/web.jpg",
  "alt":"",
  "link":"http://example.com/web/",
  "caption":""
}

我正在使用以下代码段仅使用 alt ，标题， id 和 url 数组中的键:

I'm using the following snippet to create a new array with just the alt, caption, id and url keys in the array:

images.map( ( image ) => pick( image, [ 'alt', 'caption', 'id', 'url' ] ) ),

我的问题是，如何选择 sizes.thumbnail.url 键而不是根 url 键?是否可以?如果可以，怎么办?

My question is, how can I pick the sizes.thumbnail.url key instead of the root url key? Is it possible? If so, how?

预先感谢

推荐答案

使用sizes.thumbnail.url 值的对象lodash.com/docs/4.17.10#get"rel =" nofollow noreferrer> _.get() ，并将其与 _的结果合并.pick().

Create an object with the url property and the value of sizes.thumbnail.url using _.get(), and combine it with to the results of the _.pick().

注意::我已经使用对象传播以合并结果，但是您可以使用

Note: I've used object spread to merge the results, but you can use Object.assign() or lodash's equivalent instead.

const images = [{"sizes":{"thumbnail":{"height":300,"width":300,"url":"http://example.com/wp-content/uploads/2017/04/web-300x300.jpg","orientation":"landscape"},"medium":{"height":267,"width":400,"url":"http://example.com/wp-content/uploads/2017/04/web-400x267.jpg","orientation":"landscape"},"large":{"height":441,"width":660,"url":"http://example.com/wp-content/uploads/2017/04/web-1024x684.jpg","orientation":"landscape"},"full":{"url":"http://example.com/wp-content/uploads/2017/04/web.jpg","height":1200,"width":1796,"orientation":"landscape"}},"mime":"image/jpeg","type":"image","subtype":"jpeg","id":3589,"url":"http://example.com/wp-content/uploads/2017/04/web.jpg","alt":"","link":"http://example.com/web/","caption":""}];

const result = images.map((image) => ({
  ..._.pick(image, ['alt', 'caption', 'id']),
  url: _.get(image, 'sizes.thumbnail.url')
}));

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

更通用的解决方案是一个函数，该函数接受路径列表，并生成成对的数组[路径的最后一部分，值].该函数使用 _.fromPairs() (或 Object.fromEntries() ):

A more generic solution would a function that accepts a list of paths, and generate an array of pairs [last part of path, value]. The function converts the pairs to an object using _.fromPairs() (or Object.fromEntries()):

const deepPick = (paths, obj) => 
  _.fromPairs(paths.map(p => [
    _.last(p.split('.')),
    _.get(obj, p),
  ]))

const images = [{"sizes":{"thumbnail":{"height":300,"width":300,"url":"http://example.com/wp-content/uploads/2017/04/web-300x300.jpg","orientation":"landscape"},"medium":{"height":267,"width":400,"url":"http://example.com/wp-content/uploads/2017/04/web-400x267.jpg","orientation":"landscape"},"large":{"height":441,"width":660,"url":"http://example.com/wp-content/uploads/2017/04/web-1024x684.jpg","orientation":"landscape"},"full":{"url":"http://example.com/wp-content/uploads/2017/04/web.jpg","height":1200,"width":1796,"orientation":"landscape"}},"mime":"image/jpeg","type":"image","subtype":"jpeg","id":3589,"url":"http://example.com/wp-content/uploads/2017/04/web.jpg","alt":"","link":"http://example.com/web/","caption":""}];

const result = images.map(image => deepPick(
  ['alt', 'caption', 'id', 'sizes.thumbnail.url'], 
  image
));

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

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