JavaScript failing to link an element to the object

Question

JavaScript failing to link an element to the object

const modifyTimestamp = async (request, response) => {
  try {
    const { user: userid } = request;
    if (!ObjectId.isValid(userid)) throw new Error('invalid objectid');

    const now = moment().format();
    const date = new Date(now);
    const result = await Allocation.findOne({ $and: [{ user: userid, start_date: { $lt: date }, end_date: { $gt: date } }] })
      .populate('user', 'name')
      .populate('garden');
    if (!result) throw new Error('invalid request');
    result.timestamp = moment(result.end_date).format('x');
    response.status(200).send(result);
  } catch (error) {
    response.status(400).send(error);
  }
};

I've encountered an issue where the timestamp is not added to the returned object from the MongoDB query. Even when trying to log the timestamp value, it doesn't appear. It seems like JavaScript is disregarding my assignment. I experimented with changing from const to let but that didn't solve the problem.

javascript mongodb mongoose async-await

Answer 1

Answer №1

..it seems like javascript is not recognizing my attempt to assign it.

It's a possibility that JavaScript is disregarding the assignment if the object is either sealed or frozen by MongoDB.

Instead, create a duplicate and append your property to the duplicate using ES2018's property spread:

allocation = {...allocation, timestamp: moment(allocation.end_date).format('x')};

...or if you cannot utilize property spread, use Object.assign:

allocation = Object.assign({}, allocation, {timestamp: moment(allocation.end_date).format('x')});

You will need to switch from const to let in these situations since we are altering the value stored in the variable allocation. Alternatively, you can keep it as a const and retain the modified version separately:

const updatedAllocation = {...allocation, timestamp: moment(allocation.end_date).format('x')};
response.status(200).send(updatedAllocation);

I attempted changing from const to let but it appears that's not the root of the problem.

That's correct. const pertains to the variable (allocation), not the object the variable points to.

Answer 2

..it seems like javascript is not recognizing my attempt to assign it.

It's a possibility that JavaScript is disregarding the assignment if the object is either sealed or frozen by MongoDB.

Instead, create a duplicate and append your property to the duplicate using ES2018's property spread:

allocation = {...allocation, timestamp: moment(allocation.end_date).format('x')};

...or if you cannot utilize property spread, use Object.assign:

allocation = Object.assign({}, allocation, {timestamp: moment(allocation.end_date).format('x')});

You will need to switch from const to let in these situations since we are altering the value stored in the variable allocation. Alternatively, you can keep it as a const and retain the modified version separately:

const updatedAllocation = {...allocation, timestamp: moment(allocation.end_date).format('x')};
response.status(200).send(updatedAllocation);

I attempted changing from const to let but it appears that's not the root of the problem.

That's correct. const pertains to the variable (allocation), not the object the variable points to.

Answer 3

Answer №2

The documents retrieved from the query consist of mongoose/mongodb objects, not basic javascript objects.

To make any changes to the document, you need to either assign it to new Object(), or utilize the .lean() option which converts the mongoose object to a regular javascript object.

const record = await Record.findOne({})
      .populate('user', 'name')
      .populate('garden')
      .lean()
if (!record) throw new Error('invalid request');
record.timestamp = moment(record.end_date).format('x');

Answer 4

The documents retrieved from the query consist of mongoose/mongodb objects, not basic javascript objects.

To make any changes to the document, you need to either assign it to new Object(), or utilize the .lean() option which converts the mongoose object to a regular javascript object.

const record = await Record.findOne({})
      .populate('user', 'name')
      .populate('garden')
      .lean()
if (!record) throw new Error('invalid request');
record.timestamp = moment(record.end_date).format('x');

JavaScript failing to link an element to the object

Answer №1

Answer №2

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