颤振使目录索引 [英] Flutter making a directory index

问题描述

我面临着创建带有字母索引的目录的挑战.

Im facing challenge creating a directory with alphabet index.

我有List< Map< String，dynamic>>如下的商店:

I have List<Map<String, dynamic>> of shops like below:

var shops = [
        {'name':'Thrifty','products':'cars', 'delivery':'no'},
        {'name':'Pizza Express','products':'pizza', 'delivery':'yes'},
        {'name':'Fastmart','products':'household items', 'delivery':'yes'}   
];

，并希望呈现以字母分隔的卡片列表，如下所示:

and would like to render list of cards separated with alphabet like below:

我正在使用Cloud Firestore来获取我的数据，如果有一种直接查询数据库或在客户端完成数据库的方法，请告诉我.

I'm using cloud firestore to get my data, if there is a way to query the database directly or have it done client-side please let me know.

感谢任何帮助和指导！

推荐答案

我可以给你个主意.尝试这样的事情，

I could give you an idea. Try something like this,

  var shops = [
        {'name':'Thrifty','products':'cars', 'delivery':'no'},
        {'name':'Pizza Express','products':'pizza', 'delivery':'yes'},
        {'name':'Fastmart','products':'household items', 'delivery':'yes'}   
  ];
  
  var indexedShops = {};
  
  shops.forEach((item) {
    String letter = item['name'][0];
    if(indexedShops[letter] != null){
      indexedShops[letter] += [item];
    }else{
      indexedShops[letter] = [item];
    }
  });
  
  print(indexedShops);
  
// {T: [{name: Thrifty, products: cars, delivery: no}], P: [{name: Pizza Express, products: pizza, delivery: yes}], F: [{name: Fastmart, products: household items, delivery: yes}]}
  
  var availLetters = indexedShops.keys.toList();
  availLetters.sort();

  availLetters.forEach((e){
    print(indexedShops[e]);
  });
  
// [{name: Fastmart, products: household items, delivery: yes}]
// [{name: Pizza Express, products: pizza, delivery: yes}]
// [{name: Thrifty, products: cars, delivery: no}]

首先，我们声明一个 Map 来按字母顺序存储对象.

First of all, we declare a Map to store the objects letter-wise.

然后，列出可用字母并对其进行排序以用于显示.

Then, make a list of available letters and sort them for display purposes.

然后，针对不同的用例进行遍历.

Then, iterate through it for different use cases.

希望能满足您的情况！

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