RamdaJS 转换对象并使用另一个列表进行查找 [英] RamdaJS transform object and do lookup with another lists

问题描述

继续RamdaJS groupBy 和转换对象

let children = [
  { "name": "Bob", "age": 8, "father": "Mike" },
  { "name": "David", "age": 10, "father": "Mike" },
  { "name": "Amy", "age": 2, "father": "Mike" },
  { "name": "Jeff", "age": 11, "father": "Jack" }
]

let schoolList = [
  { "name": "Bob", "class": "8-A", "school": "School 1" },
  { "name": "David", "class": "10-B", "school": "School 1" },
  { "name": "Amy", "class": "2-A", "school": "School 1" },
  { "name": "Jeff", "class": "11-C", "school": "School 1" }
]

到目前为止我做了什么.

What have i done so far.

R.pipe(
  R.groupBy(R.prop('father')),
  R.map(R.applySpec({
    father: R.pipe(R.head, R.prop('father')),
    count: R.length,
    kids: R.map(R.dissoc('father')),
    class: R.map(R.prop('class'))R.find(R.propEq('name',R.pipe(R.head, R.prop('name'))), schoolList)
  })),
  R.values()
)(children)

预期输出是 class 属性附加到嵌套的 kids 数组中.

Expected output is class property is appended to nested kids array.

{
    "father": "Jack",
    "count" : 1,
    "kids": [
      { "name": "Jeff", "age": 11, "class" : "11-C" }
    ]
  }

推荐答案

如果实际的 schoolList 很长，我会使用 OriDrori 的答案.但如果它相当短，那么这可能会更简洁一些，即使效率较低:

If the actual schoolList is quite long, I would use the answer from OriDrori. But if it's fairly short, then this might be a bit cleaner, even if less efficient:

const expandChild = schoolList => child => ({
  ...child,
  class: defaultTo(
    {class: 'unknown'}, 
    find(propEq('name', child.name), schoolList)
  ).class
})

const groupChildren = schoolList => pipe(
  groupBy(prop('father')),
  map(applySpec({
    father: pipe(head, prop('father')),
    count: length,
    kids: map(pipe(dissoc('father'), expandChild(schoolList)))
  })),
  values,
)

let children = [{ name: "Bob", age: 8, father: "Mike" }, { name: "David", age: 10, father: "Mike" }, { name: "Amy", age: 2, father: "Mike" }, { name: "Jeff", age: 11, father: "Jack" }, { name: "Sue", age: 9, father: "Jack" }]

let schoolList = [{ name: "Bob", class: "8-A", school: "School 1" }, { name: "David", class: "10-B", school: "School 1" }, { name: "Amy", class: "2-A", school: "School 1" }, { name: "Jeff", class: "11-C", school: "School 1" }]

console.log (groupChildren (schoolList) (children))

<script src="https://bundle.run/ramda@0.26.1"></script><script>
const {defaultTo, find, propEq, pipe, groupBy, map, applySpec, head, prop, length, dissoc, values} = ramda
</script>

注意 school 的默认值，以防孩子的名字不在 schoolList 中.

Note the default value given for school in case the child's name is not in schoolList.

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