javascript - 使用 lodash.groupBy() 标准化对象

Question

我有一个由三个不同对象组成的非规范化数组 - 国家、学校、学生

const input= 
 [
    {
      countryID: 12,
      country: "US",
      schoolID: 122,
      schoolZone: "Highlands",
      studentID: 142,
      studentName: "Mary"
    },
    {
      countryID: 12,
      country: "US",
      schoolID: 122,
      schoolZone: "Highlands",
      studentID: 145,
      studentName: "John"
    },
    {
      countryID: 14,
      country: "UK",
      schoolID: 222,
      schoolZone: "Leeds",
      studentID: 223,
      studentName: "Peter"
    }
  ];

我想像这样标准化它们

const result= 
 [
    {
      countryID: 12,
      country: "US",
      schools: [
        {
          schoolID: 122,
          schoolZone: "Highlands",
          students: [
            {
              studentID: 142,
              studentName: "Mary"
            },
            {
              studentID: 145,
              studentName: "John"
            }
          ]
        }
      ]
    },
    {
      countryID: 14,
      country: "UK",
      schools: [
        {
          schoolID: 222,
          schoolZone: "Leeds",
          students: [
            {
              studentID: 223,
              studentName: "Peter"
            }
          ]
        }
      ]
    }
  ];

我了解 lodash 和 ramda 可用于实现嵌套规范化

但是我对这两个库都是新手。

您能帮我实现吗？还想知道考虑到存在 schools 和 students

的嵌套，柯里化(Currying)是否会成为一个考虑因素

Answer 1

不使用 lodash 或 ramda 的方法可能是这样的。希望这会有所帮助。

const input= [{
    countryID: 12,
    country: "US",
    schoolID: 122,
    schoolZone: "Highlands",
    studentID: 142,
    studentName: "Mary"
}, {
    countryID: 12,
    country: "US",
    schoolID: 122,
    schoolZone: "Highlands",
    studentID: 145,
    studentName: "John"
}, {
    countryID: 14,
    country: "UK",
    schoolID: 222,
    schoolZone: "Leeds",
    studentID: 223,
    studentName: "Peter"
}];

const normalize = (data) =>

    data.reduce((acc, { studentID, studentName, schoolID, schoolZone, countryID, country }) => {

        const studentToAdd = { studentID, studentName };

        const schoolToAdd = { schoolID, schoolZone, students: [studentToAdd] };

        const countryToAdd = { countryID, country, schools: [schoolToAdd] };

        const existingCountry = acc.find(item => item.countryID === countryID);

        if (existingCountry) {

            const existingSchool = existingCountry.schools.find(item => item.schoolID === schoolID);

            if (existingSchool) {

                const existingStudent = existingSchool.students.find(item => item.studentID === studentID);

                if (!existingStudent) existingSchool.students.push(studentToAdd);
            }

            else existingCountry.schools.push(schoolToAdd);
        }

        else acc.push(countryToAdd);

        return acc;
    }, []);

console.log(normalize(input));