将数据数组转换为SectionList组件的分组数据

Question

我承认 Javascript 不是我最擅长的语言，而且 React Native 是非常新的，所以，可能有一种我没有看到的明显简单的方法来做到这一点。

我有一个 API，可以以简单的结构呈现一些交易数据：

[
  {
    "id": 1,
    "title": "Apple Store",
    "date": "2021-09-10",
    "amount": "$100.00",
  },
  {
    "id": 41,
    "title": "Zulauf, Walter and Metz",
    "date": "2021-09-10",
    "amount": "$14.00",
  },
  {
    "id": 9,
    "title": "Aufderhar PLC",
    "date": "2021-09-09",
    "amount": "$78.00",
  },
  {
    "id": 10,
    "title": "Bayer and Sons",
    "date": "2021-09-07",
    "amount": "$67.00",
  }
]

我想使用SectionList组件来呈现这些数据，并按日期划分交易。我（可能很粗略）解决这个问题的尝试是将这些数据转换为以下结构：

[
  {
    "date": "2021-09-10",
    "transactions": [
      {
        "id": 1,
        "title": "Apple Store",
        "date": "2021-09-10",
        "amount": "$100.00",
      },
      {
        "id": 41,
        "title": "Zulauf, Walter and Metz",
        "date": "2021-09-10",
        "amount": "$14.00",
      }
    ]
  },
  {
    "date": "2021-09-09",
    "transactions": [
      {
        "id": 9,
        "title": "Aufderhar PLC",
        "date": "2021-09-09",
        "amount": "$78.00",
      }
    ]
  },
  {
    "date": "2021-09-07",
    "transactions": [
      {
        "id": 10,
        "title": "Bayer and Sons",
        "date": "2021-09-07",
        "amount": "$67.00",
      }
    ]
  }
]

但老实说，我不知道如何转换这些数据（或者是否有更好的方法来解决这个问题）。我开始使用 Lodash 的 groupBy 函数，这看起来很有前途，但看起来SectionList不需要一个对象，它需要一个数组。

将 groupBy 的输出直接转换为数组会丢弃键，并且我得到了分组数据，但节标题没有明确的值。

同样，可能有一些非常简单的方法来解决这个问题，数据始终以平面数组的形式出现。我感谢任何人可以向我指出的任何指导、帮助或示例。

Answer 1

const input = [
  {
    "id": 1,
    "title": "Apple Store",
    "date": "2021-09-10",
    "amount": "$100.00",
  },
  {
    "id": 41,
    "title": "Zulauf, Walter and Metz",
    "date": "2021-09-10",
    "amount": "$14.00",
  },
  {
    "id": 9,
    "title": "Aufderhar PLC",
    "date": "2021-09-09",
    "amount": "$78.00",
  },
  {
    "id": 10,
    "title": "Bayer and Sons",
    "date": "2021-09-07",
    "amount": "$67.00",
  }
]

const result = input.reduce((accum, current)=> {
  let dateGroup = accum.find(x => x.date === current.date);
  if(!dateGroup) {
    dateGroup = { date: current.date, transactions: [] }
    accum.push(dateGroup);
  }
  dateGroup.transactions.push(current);
  return accum;
}, []);

console.log(result)

给定一个数组，每当您的结果期望具有相同数量的元素时，请使用

map

，但由于您的结果具有不同数量的元素，请使用

reduce

，如上所示。这个想法是通过

reduce

，循环每个元素，看看是否可以找到该元素，并将当前元素推入列表

Answer 2

lodash

groupBy

只是帮助您处理分组数据，您应该通过将分组数据转换为您的格式来处理分组数据。

const input = [
  {
    "id": 1,
    "title": "Apple Store",
    "date": "2021-09-10",
    "amount": "$100.00",
  },
  {
    "id": 41,
    "title": "Zulauf, Walter and Metz",
    "date": "2021-09-10",
    "amount": "$14.00",
  },
  {
    "id": 9,
    "title": "Aufderhar PLC",
    "date": "2021-09-09",
    "amount": "$78.00",
  },
  {
    "id": 10,
    "title": "Bayer and Sons",
    "date": "2021-09-07",
    "amount": "$67.00",
  }
];

const groupedArray = _.groupBy(input, "date");

let result = [];
for (const [key, value] of Object.entries(groupedArray)) {
   result.push({
     'date': key,
     'transactions': value
   })
}

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

Answer 3

简单

const data = 
  [ { id:  1, title: 'Apple Store',             date: '2021-09-10', amount: '$100.00' } 
  , { id: 41, title: 'Zulauf, Walter and Metz', date: '2021-09-10', amount:  '$14.00' } 
  , { id:  9, title: 'Aufderhar PLC',           date: '2021-09-09', amount:  '$78.00' } 
  , { id: 10, title: 'Bayer and Sons',          date: '2021-09-07', amount:  '$67.00' } 
  ] 

const res = Object.entries(data.reduce((r,{id,title,date,amount})=>
  {
  r[date] = r[date] ?? []
  r[date].push({id,title,date,amount})
  return r
  },{})).map(([k,v])=>({date:k,transactions:v}))

console.log( res )

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

Answer 4

使用 lodash，您可以按

date

进行分组，然后映射到所需的表格：

const input = [{"id":1,"title":"Apple Store","date":"2021-09-10","amount":"$100.00"},{"id":41,"title":"Zulauf, Walter and Metz","date":"2021-09-10","amount":"$14.00"},{"id":9,"title":"Aufderhar PLC","date":"2021-09-09","amount":"$78.00"},{"id":10,"title":"Bayer and Sons","date":"2021-09-07","amount":"$67.00"}];

const result = _.map(
  _.groupBy(input, 'date'),
  (transactions, date) => ({ date, transactions })
)

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

Answer 5

你可以使用loadash

var result = _(data)
    .groupBy(item => item.date)
    .map((value, key) => ({date: key, transactions: value}))
    .value();

Answer 6

这是我编写的一个 TypeScript 实用函数，用于执行类似的操作：

// from https://stackoverflow.com/a/49752227
type KeyOfType<T, V> = keyof {
  [P in keyof T as T[P] extends V? P: never]: any
};

// data[key] must be string, number, or symbol
export function groupBy<T>(data: T[], key: KeyOfType<T, string | number | symbol>) {
  const collect: {[index: string | number | symbol]: T[]} = {};
  for (let item of data) {
    const key_value = item[key] as string | number | symbol;
    if (key_value in collect) collect[key_value].push(item);
    else collect[key_value] = [item];
  }
  return collect;
};

关于以上数据：

const data = [
  {id: 1, title: 'Apple Store', date: '2021-09-10', amount: '$100.00'},
  {id: 41, title: 'Zulauf, Walter and Metz', date: '2021-09-10', amount: '$14.00'},
  {id: 9, title: 'Aufderhar PLC', date: '2021-09-09', amount: '$78.00'},
  {id: 10, title: 'Bayer and Sons', date: '2021-09-07', amount: '$67.00'},
];
groupBy(data, 'date');
// yields:
{
  '2021-09-07': [{id: 10, title: 'Bayer and Sons', date: '2021-09-07', amount: '$67.00'}],
  '2021-09-09': [{id: 9, title: 'Aufderhar PLC', date: '2021-09-09', amount: '$78.00'}],
  '2021-09-10': [
    {id: 1, title: 'Apple Store', date: '2021-09-10', amount: '$100.00'},
    {id: 41, title: 'Zulauf, Walter and Metz', date: '2021-09-10', amount: '$14.00'},
  ],
};