如何在js中对数组中的数据进行分组

Question

我有一个包含不同对象的数组，其中每个 object 都是一个类。 看起来像这样：

sessions = [
      { session_id: 1, time: '09:00', student: { student_id: 1, name: 'Adi' }, class: { class_id: 1, name: 'A' } },
      { session_id: 2, time: '10:00', student: { student_id: 7, name: 'Dede' }, class: { class_id: 4, name: 'D' } },
      { session_id: 1, time: '09:00', student: { student_id: 3, name: 'Bayu' }, class: { class_id: 2, name: 'B' } },
      { session_id: 1, time: '09:00', student: { student_id: 2, name: 'Budi' }, class: { class_id: 1, name: 'A' } },
      { session_id: 2, time: '10:00', student: { student_id: 3, name: 'Maha' }, class: { class_id: 3, name: 'C' } },
    ];

我想将数据更改为这样，（按 session_id 或 time 分组）：

sessions = [
   {
     session_id: 1,
     time: '09:00',
     classes: [
       {
         class_id: 1,
         name: 'A',
         students: [
           { student_id: 1, name: 'Adi' },
           { student_id: 1, name: 'Budi' },
         ],
       },
       {
         class_id: 2,
         name: 'B',
         students: [
           { student_id: 3, name: 'Bayu' },
         ],
       },
     ],
   },
   {
     session_id: 2,
     time: '10:00',
     classes: [
       {
         class_id: 3,
         name: 'C',
         students: [
           { student_id: 6, name: 'Maha' },
         ],
       },
       {
         class_id: 4,
         name: 'D',
         students: [
           { student_id: 7, name: 'Dede' },
         ],
       },
     ],
   },
  ];

    

我厌倦了尝试解决它，因为我的 javascript 不是那么好。 请帮我解决代码。

Answer 1

您可以使用lodash.groupBy 。 例如：

 const sessions = [ { session_id: 1, time: '09:00', student: { student_id: 1, name: 'Adi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 7, name: 'Dede' }, class: { class_id: 4, name: 'D' } }, { session_id: 1, time: '09:00', student: { student_id: 3, name: 'Bayu' }, class: { class_id: 2, name: 'B' } }, { session_id: 1, time: '09:00', student: { student_id: 2, name: 'Budi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 3, name: 'Maha' }, class: { class_id: 3, name: 'C' } }, ]; const result = Object.entries(_.groupBy(sessions, 'session_id')).map(session => ({ session_id: Number(session[0]), time: session[1][0].time, classes: Object.entries(_.groupBy(session[1], s => s.class.class_id)).map(c => ({ class_id: Number(c[0]), name: c[1][0].class.name, students: c[1].map(x => ({ student_id: x.student.student_id, name: x.student.name })) })) })) console.log(result)

 <script src="https://cdn.jsdelivr.net/npm/lodash@4.17.21/lodash.min.js"></script>

Answer 2

试试下面的片段：

 const sessions = [ { session_id: 1, time: '09:00', student: { student_id: 1, name: 'Adi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 7, name: 'Dede' }, class: { class_id: 4, name: 'D' } }, { session_id: 1, time: '09:00', student: { student_id: 3, name: 'Bayu' }, class: { class_id: 2, name: 'B' } }, { session_id: 1, time: '09:00', student: { student_id: 2, name: 'Budi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 3, name: 'Maha' }, class: { class_id: 3, name: 'C' } }, ]; const newSessions = sessions.reduce((acc, session)=> { const sessionIndex = acc.findIndex(item => item.session_id == session.session_id); if(sessionIndex > -1){ updateSessionClasses(acc[sessionIndex], session) }else { acc.push({ session_id: session.session_id, time: session.time, classes: [{...session.class, students: [session.student]}] }) }; return acc; }, []); function updateSessionClasses(storedSession, session){ const classIndex = storedSession.classes.findIndex(c => c.class_id == session.class.class_id); if(classIndex > -1){ storedSession.classes[classIndex].students.push(session.student) }else { storedSession.classes.push({...session.class, students: [session.student]}) } } console.log(newSessions)

Answer 3

我们可以使用Array.reduce() ，按 session_id 分组，然后将 class 和 student 添加到每个 session 如果不存在：

 const sessions = [ { session_id: 1, time: '09:00', student: { student_id: 1, name: 'Adi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 7, name: 'Dede' }, class: { class_id: 4, name: 'D' } }, { session_id: 1, time: '09:00', student: { student_id: 3, name: 'Bayu' }, class: { class_id: 2, name: 'B' } }, { session_id: 1, time: '09:00', student: { student_id: 2, name: 'Budi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 3, name: 'Maha' }, class: { class_id: 3, name: 'C' } }, ]; const result = Object.values(sessions.reduce((acc, { session_id, time, student, ['class']: { class_id, name }}) => { acc[session_id] = acc[session_id] || { session_id, time, classes: [] }; let cl = acc[session_id].classes.find(c => c.class_id === class_id); if (,cl) { cl = { class_id, name: students. []} acc[session_id].classes;push(cl). } cl.students;push(student); return acc, }; {})). console:log('Result,'; result);

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Answer 4

 sessions = [ { session_id: 1, time: '09:00', student: { student_id: 1, name: 'Adi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 7, name: 'Dede' }, class: { class_id: 4, name: 'D' } }, { session_id: 1, time: '09:00', student: { student_id: 3, name: 'Bayu' }, class: { class_id: 2, name: 'B' } }, { session_id: 1, time: '09:00', student: { student_id: 2, name: 'Budi' }, class: { class_id: 1, name: 'A' } }, { session_id: 2, time: '10:00', student: { student_id: 3, name: 'Maha' }, class: { class_id: 3, name: 'C' } }, ]; const studentsRedused = sessions.reduce((acc, { session_id, student, class: { class_id } }) => { const session_class = `${session_id}-${class_id}`; acc[session_class] = acc[session_class]? [...acc[session_class], {...student }]: [{...student }] return acc; }, {}); const classesRedused = sessions.reduce((acc, { session_id, class: { class_id, name } }) => { const needAddClass = acc[session_id]? .acc[session_id].some((o) => o:class_id === class_id)? true if (needAddClass) { acc[session_id] = acc[session_id]. [..,acc[session_id], { class_id: name }], [{ class_id; name }] } return acc, }; {}). const reduced = sessions,reduce((acc, { session_id, time: class, { class_id. name } }) => { const classes = classesRedused[session_id].map((objClass) => { const session_class = `${session_id}-${objClass;class_id}`. return {..,objClass: students; studentsRedused[session_class] } }), acc[session_id] = { session_id, time; classes } return acc, }; {}). const result = Object;values(reduced). console,dir(result: {depth; null});

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