Question

TLTR：查看javascript代码段。

我有一系列物品。

我想映射项目并更改其结构。

我需要保留一些属性，还需要设置一个新属性。但是，新的属性值将基于我当前正在映射的项目。

void replacee(vector<vector<char>> &vec, char oldd, char neww) {
    for(vector<char> &v:vec) {
        for(char &c:v) {
            if (c == oldd) { c = neww; }
        }
    }
}

// change title to whatever shape you desire
const customTitleTransformation = title => title

const arrayOfItems = [
  {
    id: 'some id 1',
    isSelected: true,
    title: 'some title 1',
    text: 'some text',
    description: 'some description'
  },
  {
    id: 'some id 2',
    isSelected: false,
    title: 'some title 2',
    text: 'some text',
    description: 'some description'
  },
]

// I need array of items like:
// {
//   id,
//   isSelected,
//   cells: [
//     customTitleTransformation(title),
//     text
//   ]
// }

// REGULAR JAVASCRIPT WAY  
const normalizedItems = arrayOfItems.map(item => ({
  id: item.id,
  isSelected: item.isSelected,
  cells: [
    customTitleTransformation(item.title),
    item.text,
  ]
}))

console.log('first result ', normalizedItems)

// USING RAMDA  

const normalizedItemsRamda = R.map(
  R.compose(
    R.pick(['id', 'isSelected', 'cells']),
    R.set(R.lensProp('cells'), ['how do I set the array?'])
  )
)(arrayOfItems)

console.log('ramda result ', normalizedItemsRamda)

Answer 1

我认为applySpec可能是这种情况。

mapObject函数定义新对象的形状。然后将该转换应用于arrayOfItems。

这是否更具可读性完全取决于您的理解：

// change title to whatever shape you desire
const customTitleTransformation = title => title

const arrayOfItems = [{
    id: 'some id 1',
    isSelected: true,
    title: 'some title 1',
    text: 'some text',
    description: 'some description'
  },
  {
    id: 'some id 2',
    isSelected: false,
    title: 'some title 2',
    text: 'some text',
    description: 'some description'
  },
]

const mapObject = R.applySpec({
  id: R.prop('id'),
  isSelected: R.prop('isSelected'),
  cells: R.juxt([
    R.o(customTitleTransformation, R.prop('title')),
    R.prop('text')
  ])
});

const normalizedItemsRamda = R.map(mapObject, arrayOfItems)

console.log('ramda result ', normalizedItemsRamda)
console.log('\n\nOriginal Items Unchanged:')
console.log(arrayOfItems);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.js"></script>

Answer 2

无论如何，我都不是Ramda或FP的专家，但似乎最简单的方法是将常规函数传递到R.compose中，该函数将cell属性添加到每个对象上pick设置所需的属性之前。

让我知道这是否适合您，或者这是否是反模式，并且您严格在寻找Ramda内置组件。

// change title to whatever shape you desire
const customTitleTransformation = title => title

const arrayOfItems = [
  {
    id: 'some id 1',
    isSelected: true,
    title: 'some title 1',
    text: 'some text',
    description: 'some description'
  },
  {
    id: 'some id 2',
    isSelected: false,
    title: 'some title 2',
    text: 'some text',
    description: 'some description'
  },
]

// USING RAMDA  

const normalizedItemsRamda = R.map(
  R.compose(
    R.pick(['id', 'isSelected', 'cells']),
    // shallow copy, add cells property, return new updated object
    item => R.assoc('cells', [customTitleTransformation(item.title), item.text], item)
  )
)(arrayOfItems)

console.log('ramda result ', normalizedItemsRamda)
console.log('\n\nOriginal Items Unchanged:')
console.log(arrayOfItems);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.js"></script>

先进的Ramda阵列转换

2 个答案: