SQL results into nested Javascript object

Question

I have SQL results that are returned in Javascript like this:

{
  machine_class: 'MAN',
  machine: '001',
  start: '2020-01-02 18:27:38',
  end: '2020-01-02 18:30:22',
  code: 'ready'
},
{
  machine_class: 'CMD',
  machine: '002',
  start: '2020-01-02 18:30:22',
  end: '2020-01-02 18:30:53',
  code: 'ready'
},
{
  machine_class: 'CMD',
  machine: '002',
  start: '2020-01-02 18:30:53',
  end: '2020-01-02 18:31:16',
  code: 'delay'
},
{
  machine_class: 'CMD',
  machine: '003',
  start: '2020-01-02 18:31:16',
  end: '2020-01-02 18:31:29',
  code: 'ready'
}

I need to nest the results first by machine_class, then by machine like this:

[
  {
    machine_class: "CMD",
    data: [
      {
        machine: "002",
        data: [
          {
            timeRange: ['2020-01-02 18:30:22', '2020-01-02 18:30:53'],
            val: 'ready' 
          },
          {
            timeRange: ['2020-01-02 18:30:53', '2020-01-02 18:31:16'],
            val: 'delay'
          },
          (...)
        ]
      },
      {
        machine: "003",
        data: [...]
      },
      (...)
    ],
  },
  {
    machine_class: "MAN",
    data: [...]
  },
  (...)
]

The only solutions I can come up with are complicated and slow, is there anything inbuilt to JavaScript that can nest objects like this?

Answer 1

Should not be so slow in case you are using Object for indexing, is output OK ?

Below line is also indexed source to better understand how it works as it is a data driven algo.

 var dbInput = [{ machine_class: 'MAN', machine: '001', start: '2020-01-02 18:27:38', end: '2020-01-02 18:30:22', code: 'ready' }, { machine_class: 'CMD', machine: '002', start: '2020-01-02 18:30:22', end: '2020-01-02 18:30:53', code: 'ready' }, { machine_class: 'CMD', machine: '002', start: '2020-01-02 18:30:53', end: '2020-01-02 18:31:16', code: 'delay' }, { machine_class: 'CMD', machine: '003', start: '2020-01-02 18:31:16', end: '2020-01-02 18:31:29', code: 'ready' }]; var res = convert(dbInput); var merge = res.pop(); document.body.innerHTML = '<PRE>var Result = ' + JSON.stringify(res,null,2) + '</PRE>' + '<HR>' + '<PRE>var IndexedSource = ' + JSON.stringify(merge,null,2) + '</PRE>'; function convert (dbInput) { var merge = {}; for (var r = 0; r < dbInput.length; r++) { var row = dbInput[r]; var classIndex; var machineIndex; do { classIndex = merge[row.machine_class]; merge[row.machine_class] = classIndex || {}; } while (classIndex === undefined); do { machineIndex = classIndex[row.machine]; classIndex[row.machine] = machineIndex || []; } while (machineIndex === undefined); machineIndex.push({ timeRange: [row.start, row.end], val: row.code }); } var result = []; for (var machineClass in merge) { var machineClassElement = { machine_class: machineClass, data: [] }; result.push(machineClassElement); var data = machineClassElement.data; machineClassElement = merge[machineClass]; for (var machine in machineClassElement) { data.push({ machine: machine, data: machineClassElement[machine] }); } } result.push(merge); // merged data before final reorder return result; }