Question

我有一个像这样的对象数组：

    users: [
        { name: 'missing!', ids: ['Not Specified']},
        { name: 'user1', ids: ['C.001', 'C.002', 'C.001.001']},
        { name: 'user2', ids: ['C.001', 'C.002', 'C.004', 'C.001.001']},
        { name: 'user3', ids: ['C.001', 'C.002', 'C.004', 'C.001.001']},
        { name: 'user4', ids: ['C.001', 'C.002', 'C.004', 'C.001.001']}
      ]

我想要实现的是获取一个具有一定ID的用户名数组。

例如，如果我传递一个ID：'C.001.001'，则应返回['user1'，'user2'，'user3'，'user4']。

如果我通过'C.123214123'，则应该返回['missing！']。

我尝试过但没有用的东西：

getUserNamesById(id: string) string[] {
   return _.map(this.users, user => {
         return _.find(user.ids,{id});
});}

这不起作用，也无法处理您找不到ID并返回['missing']（并且也不会返回name属性）的情况。

我是_.lodash的新手，我想学习它，但是我研究了将近2个小时，却一无所获。

我如何实现输出？

Answer 1

您需要分别处理“遗失”案。

您需要过滤列表以获取匹配的内容
如果有匹配项，请映射以获取名称
否则得到“丢失”记录

const users = [
    { name: 'missing!', ids: ['Not Specified']},
    { name: 'user1', ids: ['C.001', 'C.002', 'C.001.001']},
    { name: 'user2', ids: ['C.001', 'C.002', 'C.004', 'C.001.001']},
    { name: 'user3', ids: ['C.001', 'C.002', 'C.004', 'C.001.001']},
    { name: 'user4', ids: ['C.001', 'C.002', 'C.004', 'C.001.001']}
];
      
function find(u, search) {
  const found = _.filter(u, (x) => _.some(x.ids, (id) => id === search));
  if (_.isEmpty(found)) {
    return ['missing!'];
  } else {
    return _.map(found, (f) => f.name);
  }
}
      
console.log(find(users, 'C.001.001'));
console.log(find(users, 'C.123.456'));

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.11/lodash.min.js"></script>

Answer 2

您可以将"HEADER_ROW1_COL1,WITH_COMMA",HEADER_ROW1_COL2,my darling's ccc DATA_ROW2_COL1,DATA_ROW2_COL2 DATA_ROW3_COL1,DATA_ROW3_COL2与Array.filtered()（或类似的破折号）一起使用，以过滤数组，然后使用Array.includes()获取名称列表：

Array.map()

与lodash/fp的想法相同：

const filterById = (id, arr) => {
  const filtered = arr.filter(({ ids }) => ids.includes(id))
    .map(({ name }) => name);
  
  return filtered.length ? filtered : ['missing'];
}

const users = [{"name":"missing!","ids":["Not Specified"]},{"name":"user1","ids":["C.001","C.002","C.001.001"]},{"name":"user2","ids":["C.001","C.002","C.004","C.001.001"]},{"name":"user3","ids":["C.001","C.002","C.004","C.001.001"]},{"name":"user4","ids":["C.001","C.002","C.004","C.001.001"]}]
      
console.log(filterById('C.001.001', users));
console.log(filterById('132133333', users));

const { flow, filter, get, includes, map, cond, isEmpty, constant, stubtrue, identity } = _

const filterById = id => flow(
  filter(flow(get('ids'), includes(id))),
  cond([
    [isEmpty, constant(['missing'])],
    [stubtrue, map('name')]
  ])
)

const users = [{"name":"missing!","ids":["Not Specified"]},{"name":"user1","ids":["C.001","C.002","C.001.001"]},{"name":"user2","ids":["C.001","C.002","C.004","C.001.001"]},{"name":"user3","ids":["C.001","C.002","C.004","C.001.001"]},{"name":"user4","ids":["C.001","C.002","C.004","C.001.001"]}]
      
console.log(filterById('C.001.001')(users));
console.log(filterById('132133333')(users));

Lodash _.map获取对象数组的属性

2 个答案: