How to perform FIND, then perform AND, then perform OR with POPULATE in Mongoose

Question

I have a query that I wish to perform something similar as:

1. Archive does not exists AND
2. Owner Email in schema is in Query OR
3. Owner Email in Populated's schema is in Query

Below is what I have tried as of my understanding

    let docs = await Document.find({ archive: { $exists: false }})
      .and([{ owner_email: { $regex: localQuery } }])
      .or()
      .populate('owner_id', null, {
        email: { $regex: localQuery },
      });

So what I wish to do is, I have two schema, the user and the documents, User sometimes is shared along [as a librarian], then I wish to return, both, which matches the populated email or the actual owner's email.

Answer 1

As mongoose's populate() method does not really "join" collections and rather makes another query to the database to populate after the find() operation, you can switch to an aggregation pipeline and use $lookup in order to match the email in the referenced field. So assuming your models look like:

const Document = mongoose.model('Document', {
    name: String,
    archive: String, 
    owner_email: String,
    owner: {type: Schema.Types.ObjectId, ref: 'Person'}
});

const Person = mongoose.model('Person', {
    firstName: String,
    lastName: String,
    email: String
});

Then, you can do:

const result = await Document.aggregate([
        {
            $lookup: {
                from: Person.collection.name,
                localField: "owner",
                foreignField: "_id",
                as: "referencedOwner"
            }
        },
        {
            $match: {
                archive: {$exists: false},
                $or: [
                    {"referencedOwner.email": {$regex: localQuery}},
                    {"owner_email": {$regex: localQuery}}]
            }
        }
    ]);

Here's a working example on mongoplayground: https://mongoplayground.net/p/NqAvKIgujbm