Non-Date types that store Date values cannot be rendered as a time-based Chart about forest-express-mongoose

[ansh]

After some debugging, I was able to fix the raw query that was in the logs before forest-express-mongoose failed.

Original query:

order.aggregate(
  [
    {$match: {created_on: {$ne: null}}},
    {
      $group: {
        _id: {
          year: {$year: [{$subtract: ['$created_on', -18000000]}]},
          month: {$month: [{$subtract: ['$created_on', -18000000]}]},
          day: {$dayOfMonth: [{$subtract: ['$created_on', -18000000]}]},
        },
        created_on: {$first: '$created_on'},
        count: {$sum: 1},
      },
    },
    {$sort: {created_on: 1}},
    {$project: {values: {key: '$_id', value: '$count'}}},
  ],
  {},
);

---

Fixed query:

db.order.aggregate(
  [
    {$match: {created_on: {$ne: null}}},
    {
      $group: {
        _id: {
          year: {$year: [{$toDate: {$subtract: ['$created_on', -18000000]}}]},
          month: {$month: [{$toDate: {$subtract: ['$created_on', -18000000]}}]},
          day: {$dayOfMonth: [{$toDate: {$subtract: ['$created_on', -18000000]}}]},
        },
        created_on: {$first: '$created_on'},
        count: {$sum: 1},
      },
    },
    {$sort: {created_on: 1}},
    {$project: {values: {key: '$_id', value: '$count'}}},
  ],
  {},
);

Clearly, the fix was adding $toDate in front of $year, $month, and $dayOfMonth. This worked because all 3 of those commands take in only a Date object according to MongoDB. Therefore, we needed to convert our Int64 Epoch time to a Date before passing it into the query.

The question still remains: What is the problem in the Source Code and how to fix it?