javascript nested Json object from flat object

Question

how do i create nested Json object from flat object. if hod and dep code is same for different objects then add in same nested object. /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// my flat object is ==>>

flatObj = [
 {
 hod : '1000',
 dep : '2',
 teacher : 'avi',
 teacherno : '121',
 teacheradd : 'mumbai',
 teacheraddno : '133',
 billtoname : 'manisha',
 billtono : '77',
 payname : 'mann',
 payno : '99'
 },
 {
 hod : '1567',
 dep : '2',
 teacher : 'shetty',
 teacherno : '166',
 teacheradd : 'gujrat',
 teacheraddno : '190',
 billtoname : 'annu',
 billtono : '87',
 payname : 'kiru',
 payno : '495'
 },
 {
 hod : '1567',
 dep : '2',
 teacher : 'shetty',
 teacherno : '166',
 teacheradd : 'gujrat',
 teacheraddno : '190',
 billtoname : 'raina',
 billtono : '03',
 payname : 'kiru',
 payno : '495'
 },
 {
 hod : '1000',
 dep : '2',
 teacher : 'kisha',
 teacherno : '654',
 teacheradd : 'pune',
 teacheraddno : '986',
 billtoname : 'kittu',
 billtono : '576',
 payname : 'hayat',
 payno : '96'
 }
];
 

and i want my nested object like

nestedObj = [
 {
 hod : '1000',
 dep : '2',
 teacherArr : [
 {
 teacher : 'avi',
 teacherno : '121',
 teacheraddArr : [
 {
 teacheradd : 'mumbai',
 teacheraddno : '133',
 billtoArr : [
 {
 billtoname : 'manisha',
 billtono : '77',
 payerArr : [
 {
 payname : 'mann',
 payno : '99'
 }
 ]
 }
 ]
 }
 ]
 },
 {
 teacher : 'kisha',
 teacherno : '654',
 teacheraddArr : [
 {
 teacheradd : 'pune',
 teacheraddno : '986',
 billtoArr : [
 {
 billtoname : 'kittu',
 billtono : '576',
 payerArr : [
 {
 payname : 'hayat',
 payno : '96'
 }
 ]
 }
 ]
 }
 ]
 }
 ]
 },
 {
 hod : '1567',
 dep : '2',
 teacherArr : [
 {
 teacher : 'shetty',
 teacherno : '166',
 teacheraddArr : [
 {
 teacheradd : 'gujrat',
 teacheraddno : '190',
 billtoArr : [
 {
 billtoname : 'annu',
 billtono : '87',
 payerArr : [
 {
 payname : 'kiru',
 payno : '495'
 }
 ]
 },
 {
 billtoname : 'raina',
 billtono : '03',
 payerArr : [
 {
 payname : 'kiru',
 payno : '495'
 }
 ]
 }
 ]
 }
 ]
 }
 ]
 }
];

• adiga: Why are you nesting?
• manoj: so that no need to do filtering afterwards
• Jannes Carpentier: @manoj If any of these answers solve your problem and you do not need any additional help, please consider accepting it. Thanks!

Answer 1

I wrote some code that converts the flatObj you gave to the nestedObj you gave. You didn't specify any criteria so it might not do exactly what you want.

Edit added a whole lot of if else to check for each step.

flatObj = [{
 hod: '1000',
 dep: '2',
 teacher: 'avi',
 teacherno: '121',
 teacheradd: 'mumbai',
 teacheraddno: '133',
 billtoname: 'manisha',
 billtono: '77',
 payname: 'mann',
 payno: '99'
 },
 {
 hod: '1567',
 dep: '2',
 teacher: 'shetty',
 teacherno: '166',
 teacheradd: 'gujrat',
 teacheraddno: '190',
 billtoname: 'annu',
 billtono: '87',
 payname: 'kiru',
 payno: '495'
 },
 {
 hod: '1567',
 dep: '2',
 teacher: 'shetty',
 teacherno: '166',
 teacheradd: 'gujrat',
 teacheraddno: '190',
 billtoname: 'raina',
 billtono: '03',
 payname: 'kiru',
 payno: '495'
 },
 {
 hod: '1000',
 dep: '2',
 teacher: 'kisha',
 teacherno: '654',
 teacheradd: 'pune',
 teacheraddno: '986',
 billtoname: 'kittu',
 billtono: '576',
 payname: 'hayat',
 payno: '96'
 }
];
const nestedObj = [];
flatObj.forEach(item => {
 if (!nestedObj.some(x => x.hod == item.hod && x.dep == item.dep)) {
 nestedObj.push({
 hod: item.hod,
 dep: item.dep,
 teacherArr: []
 });
 }
 const teacherArr = nestedObj.find(x => x.hod == item.hod && x.dep == item.dep).teacherArr;
 if (!teacherArr.some(x => x.teacher == item.teacher && x.teacherno == item.teacherno)) {
 teacherArr.push({
 teacher: item.teacher,
 teacherno: item.teacherno,
 teacheraddArr: []
 });
 }
 const teacheraddArr = teacherArr.find(x => x.teacher == item.teacher && x.teacherno == item.teacherno).teacheraddArr;
 if (!teacheraddArr.some(x => x.teacheradd == item.teacheradd && x.teacheraddno == x.teacheraddno)) {
 teacheraddArr.push({
 teacheradd: item.teacheradd,
 teacheraddno: item.teacheraddno,
 billtoArr: []
 });
 }
 const billtoArr = teacheraddArr.find(x => x.teacheradd == item.teacheradd && x.teacheraddno == x.teacheraddno).billtoArr;
 if (!billtoArr.some(x => x.billtoname == item.billtoname && x.billtono == item.billtono)) {
 billtoArr.push({
 billtoname: item.billtoname,
 billtono: item.billtono,
 payerArr: []
 });
 }
 const payerArr = billtoArr.find(x => x.billtoname == item.billtoname && x.billtono == item.billtono).payerArr;
 payerArr.push({
 payname: item.payname,
 payno: item.payno
 });
})
console.log(nestedObj);

• manoj: criteria is very hard to explain. thanks this is very helpful.
• manoj: i updated my question by adding 1 criteria as you see in my flatObj array index 1 and 2 are same except billtoname and billtono but their payname and payno is same. so as you see in my nestedObj how my billtoArr should look like. Thanks in advance...
• Jannes Carpentier: I edited the code to check each step if it already exists. This should do what you want.
• manoj: Thank you sir. this is exactly what i wanted. Thanks alot.

Answer 2

You could take an array of the wanted nested groups with their joined key and array for the lower nested group.

At the end push the rest of the unused properties to the most nested array.

const
 data = [{ hod: '1000', dep: '2', teacher: 'avi', teacherno: '121', teacheradd: 'mumbai', teacheraddno: '133', billtoname: 'manisha', billtono: '77', payname: 'mann', payno: '99' }, { hod: '1567', dep: '2', teacher: 'shetty', teacherno: '166', teacheradd: 'gujrat', teacheraddno: '190', billtoname: 'annu', billtono: '87', payname: 'kiru', payno: '495' }, { hod: '1000', dep: '2', teacher: 'kisha', teacherno: '654', teacheradd: 'pune', teacheraddno: '986', billtoname: 'kittu', billtono: '576', payname: 'hayat', payno: '96' }],
 groups = [
 [['hod', 'dep'], 'teacherArr'],
 [['teacher', 'teacherno'], 'teacheraddArr'],
 [['teacheradd', 'teacheraddno'], 'billtoArr'],
 [['billtoname', 'billtono'], 'payerArr']
 ],
 result = data.reduce((r, o) => {
 groups
 .reduce((t, [keys, array]) => {
 let temp = t.find(q => keys.every(k => o[k] === q[k])),
 _;
 if (!temp) t.push(temp = { ...Object.fromEntries(keys.map(k => [k, o[k]])), [array]: [] });
 keys.forEach(k => ({ [k]: _, ...o } = o));
 return temp[array];
 }, r)
 .push(o);
 return r;
 }, []);
console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

• manoj: Thank you.it works fine for me. Also something new concept i learned from this is the way you use groups array. thanks...