VueJS 显示分组的对象数组 [英] VueJS display grouped array of objects

问题描述

我正在从 API 中获取国家/地区列表，我想按次区域(大陆)分组显示它们.像这样:

I'm fetching a list of countries from the API and I want to display them in groups by subregion (continent). Like that:

API 给我一个响应，它是一个对象(国家)数组，每个对象都有一个名为子区域"的键 - 我想按该键进行分组.我使用lodash进行分组，但也许有一个我不熟悉的Vue方法.我的 JS 代码:

API gives me a response which is an array of objects (countries) and for each object there is a key called 'subregion' - I want to group by that key. I use lodash for grouping, but maybe there is a Vue method I'm not familiar with. My JS code:

var app = new Vue({
  el: '#app',

  data: {
    countries: null,
  },

  created: function () {
    this.fetchData();
  },

  methods: {
    fetchData: function() {
      var xhr = new XMLHttpRequest();
      var self = this;
      xhr.open('GET', apiURL);
      xhr.onload = function() {
        var countryList = JSON.parse(xhr.responseText);
        self.countries = _.groupBy(countryList, "subregion");
      };
      xhr.send();
    },
  },
});

还有 HTML:

<li v-for="country in countries">
        {{ country.name }} (+{{ country.callingCodes[0] }})
</li>

我怎样才能实现图片中的内容?

How can I achieve what's in the picture?

推荐答案

您已经使用 lodash 和以下代码正确地按子区域对国家进行了分组.

You've correctly grouped countries by their subregion using lodash with the following code.

_.groupBy(countryList, "subregion")

这为您提供了一个对象，其键是子区域的名称，值是具有此类子区域的对象数组.

This has given you an object whose keys are names of subregions, and the values are arrays of objects with such subregion.

所以您的错误是您希望 countries 中的值包含 name.相反，它包含一个 array 具有 names 的对象.

So your mistake is that you expect a value in countries to contain name. Instead, it contains an array of objects with names.

为此，您需要两个 for 循环.

You need two for-loops for this.

这是一个普通的实现.这里也是一个bin.

Here's a vanilla implementation. Here's a bin, too.

fetch('https://restcountries.eu/rest/v2/all')
  .then(r => r.json())
  .then(data => {
    const grouped = _.groupBy(data, 'subregion')
    const listOfSubregions = Object.keys(grouped)

    listOfSubregions.forEach(key => {
      console.log(' =========== ' + key + ' =========== ')
      const countriesInThisSubregion = grouped[key]
      countriesInThisSubregion.forEach(country => {
        console.log(country.name + ' ' + country.callingCodes[0])
      })
    })
  })

使用 Vue，您将拥有类似以下的内容(未经测试，但根据上面的代码应该非常容易推断).

With Vue, you'd have something like the following (not tested, but should be super-easy to deduce based on the above code).

<li v-for="subregion in subregions">
  <ul>
    <li v-for="country of subregion">
        {{ country.name }} ({{ country.callingCodes[0] }})
    </li>
  </ul>
</li>

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