使用 Ramda 在特定条件下添加对象 属性 值

Question

我是 Ramda 的新手，在尝试进行一些对象转换时遇到了困难。

我有一个对象数组，必须映射它并转换每个对象。

想要的转换：

1. 重命名每个对象键
2. 根据另一个键（向每个对象添加新键（值取决于条件)

代码如下：

初始数组：

const items = [
  {
    id: 1,
    name: 'Name 1',
    factors: [
      { id: 11, name: '11', },
      { id: 12, name: '12', },
      { id: 13, name: '13', },
      { id: 14, name: '14', },
      { id: 15, name: '15', },
    ]
  },
  {
    id: 2,
    name: 'Name 2',
    factors: [],
  },
];

需要输出数组：

const items = [
  {
    key: 1,           // changed property key - already done
    title: 'Name 1',  // changed property key - already done
    factors: [
      { id: 11, name: '11', },
      { id: 12, name: '12', },
      { id: 13, name: '13', },
      { id: 14, name: '14', },
      { id: 15, name: '15', },
    ],
    // add property icon (done)
    // set icon prop based on factors length
    icon: '',        
  },
  {
    key: 2,
    title: 'Name 2',
    // add property icon (done)
    // set icon prop based on factors length
    icon: 'icon'
  },
];

上面列表中的第一个目标已完成 - 我可以更改每个对象的属性键。 我还可以为每个对象添加一个新键。但是我不能设置这个新的属性一个值基于因素Array.length.

当前代码如下：

const items = [
  {
    id: 1,
    name: 'Name 1',
    factors: [
      { id: 11, name: '11', },
      { id: 12, name: '12', },
      { id: 13, name: '13', },
      { id: 14, name: '14', },
      { id: 15, name: '15', },
    ]
  },
  {
    id: 2,
    name: 'Name 2',
  },
];

const renameKeys = curry((keysMap, obj) =>
  reduce((acc, key) => assoc(keysMap[key] || key, obj[key], acc), {}, keys(obj))
);

const result = map(pipe(
  renameKeys({ id: 'key', name: 'title' }),
  assoc('icon', '---'),  // <= here, set it based on condition - factors.length
), items);

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.min.js"  crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<script> const {curry, assoc, map, pipe, reduce, keys} = R </script>

Answer 1

Ramda 有 2 个有用的方法来转换对象 - R.evolve, and R.applySpec。这两种方法都接受一个带有键的对象，以及每个键的转换/创建（取决于方法）函数。

在这种情况下，您可以使用 R.applySpec 生成具有所需键名和值的新对象。

const { map, applySpec, prop, pipe, length, ifElse, always } = R;

const selectIcon = pipe(prop('factors'), length, ifElse(isNaN, always('icon1'), always('icon2')))

const fn = map(applySpec({
  key: prop('id'),
  title: prop('name'),
  factors: prop('factors'),
  icon: selectIcon
}));

const items = [{"id":1,"name":"Name 1","factors":[{"id":11,"name":"11"},{"id":12,"name":"12"},{"id":13,"name":"13"},{"id":14,"name":"14"},{"id":15,"name":"15"}]},{"id":2,"name":"Name 2"}];

const result = fn(items);

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.js" integrity="sha512-3sdB9mAxNh2MIo6YkY05uY1qjkywAlDfCf5u1cSotv6k9CZUSyHVf4BJSpTYgla+YHLaHG8LUpqV7MHctlYzlw==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

转换器函数也可以使用 R.applySpec 来改变嵌套值：

const { map, applySpec, prop, pipe, when, length, ifElse, always } = R;

const selectIcon = pipe(prop('factors'), length, ifElse(isNaN, always('icon1'), always('icon2')))

const keysUpdater = {
  key: prop('id'),
  title: prop('name'),
};

const factorsTransformer = pipe(prop('factors'), when(length, map(applySpec(keysUpdater))));

const fn = map(applySpec({
  ...keysUpdater,
  factors: factorsTransformer,
  icon: selectIcon
}));

const items = [{"id":1,"name":"Name 1","factors":[{"id":11,"name":"11"},{"id":12,"name":"12"},{"id":13,"name":"13"},{"id":14,"name":"14"},{"id":15,"name":"15"}]},{"id":2,"name":"Name 2"}];

const result = fn(items);

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.js" integrity="sha512-3sdB9mAxNh2MIo6YkY05uY1qjkywAlDfCf5u1cSotv6k9CZUSyHVf4BJSpTYgla+YHLaHG8LUpqV7MHctlYzlw==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>