使用 Ramda 在特定条件下添加对象属性值

Posted 2023-03-15

【中文标题】使用 Ramda 在特定条件下添加对象属性值

【英文标题】：Add object property value on particular condition with Ramda

【发布时间】：2021-09-20 08:56:31

【问题描述】：

我是 Ramda 的新手，在尝试进行一些对象转换时遇到了一面墙。

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：

重命名每个对象键 为每个对象添加新键，基于另一个键（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: [],
  ,
];

想要的输出数组：

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。但我无法设置这个新属性的值基于因素 Array.length。

这是当前代码：

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>

【参考方案1】：

Ramda 有 2 个有用的方法来转换对象 - R.evolve 和 R.applySpec。两种方法都接受带有键的对象，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 来更改嵌套值：

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>

【讨论】：

另外，如果我想映射 [factors] 键并更改每个对象键：键 [id] 变为 [key] 键 [name] 变为 [title] 什么是更清洁大大地？我尝试映射 [prop('factors')] 但没有成功。

key [name] 变成空字符串？

新键 [title] 与旧 [name] 的值一致，新键 [key] 与 [id] 的值一致。基本上，只需更改键和值以保持不变。

我添加了另一个示例

太棒了！感谢您的帮助 Ori！ :-)