Ramda：将重复的数组转换为对象

Question

使用ramda转换对象中包含重复项的数组

    var testData = [
    {"id" : "001",
        "project" : "one",
        "projectstartDate" : "10/12/2018"
    },{"id" : "001",
        "project" : "two",
        "projectstartDate" : "10/14/2018"
    },{"id"  : "002",
        "project" : "one",
        "projectstartDate" : "10/12/2018"
    },{"id"  : "002",
        "project" : "two",
        "projectstartDate" : "10/14/2018"
    }
]

---

需要获取为

{
"001" : {
    "one" : {
        "projectstartDate" : "10/12/2018"
    },
    "two" : {
        "projectstartDate" : "10/14/2018"
    }
},
"002" :{
    "one" : {
        "projectstartDate" : "10/12/2018"
    },
    "two" : {
        "projectstartDate" : "10/14/2018"
    }
}

---

创建以id为键的对象并删除重复项

Answer 1

我们将其分解为几个步骤。

首先，当您具有要通过某种功能组合在一起的事物的列表时，类似R.groupBy的内容可能会有所帮助。在此特定实例中，您想按id属性分组，因此R.prop('id')可以用作赋予R.groupBy的函数。

const testData = [
    {"id" : "001",
        "project" : "one",
        "projectstartDate" : "10/12/2018"
    },{"id" : "001",
        "project" : "two",
        "projectstartDate" : "10/14/2018"
    },{"id"  : "002",
        "project" : "one",
        "projectstartDate" : "10/12/2018"
    },{"id"  : "002",
        "project" : "two",
        "projectstartDate" : "10/14/2018"
    }
]

console.log(R.groupBy(R.prop('id'), testData))

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

将这些分组后，您希望在按某个值索引的对象中转换列表，这通常是达到R.indexBy的好时机。因为我们要索引与每个分组对象的键关联的每个列表，所以我们需要在对象上R.map。

const testData = {
  "001": [
    {
      "id": "001",
      "project": "one",
      "projectstartDate": "10/12/2018"
    },
    {
      "id": "001",
      "project": "two",
      "projectstartDate": "10/14/2018"
    }
  ],
  "002": [
    {
      "id": "002",
      "project": "one",
      "projectstartDate": "10/12/2018"
    },
    {
      "id": "002",
      "project": "two",
      "projectstartDate": "10/14/2018"
    }
  ]
}

console.log(
  R.map(R.indexBy(R.prop('project')), testData)
)

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

然后，我们必须清除嵌套对象中剩余的剩余属性。您在此处有几个选择，即通过声明要使用R.omit删除的属性或要使用R.pick保留的属性。

const testData = {
  "id" : "001",
  "project" : "one",
  "projectstartDate" : "10/12/2018"
}

console.log(
  R.pick(['projectstartDate'], testData)
)

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

现在剩下的就是使用R.pipe和R.map通过管道将其全部连接起来。

const testData = [
    {"id" : "001",
        "project" : "one",
        "projectstartDate" : "10/12/2018"
    },{"id" : "001",
        "project" : "two",
        "projectstartDate" : "10/14/2018"
    },{"id"  : "002",
        "project" : "one",
        "projectstartDate" : "10/12/2018"
    },{"id"  : "002",
        "project" : "two",
        "projectstartDate" : "10/14/2018"
    }
]

const fn = R.pipe(
  R.groupBy(R.prop('id')),
  R.map(R.pipe(
      R.indexBy(R.prop('project')),
      R.map(R.pick(['projectstartDate']))
  ))
)

console.log(
  fn(testData)
)

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