Virtual population doesn't show any result at all ! i

[xmarya]

I have a parent schema (tours) and a child schema (reviews), Each tour has many user reviews. my problem is no matter what I do the reviews won't be populated when I query a specific tour as I want it to do

Reviews Schema has a fields called tour and writer:

tour: {
       type: mongoose.Schema.Types.ObjectId,
       ref: "Tour",
       required: true,
     },
 writer: {
   type: mongoose.Schema.Types.ObjectId,
   ref: "User",
   required: true,
 },

Tours Schema is going to populate (virtual populate) all reviews related to it:

    // Virtual Populate :
    tourSchema.virtual("reviews", {
      ref:"Review",
      // specifing the names of the fields (the foreign field and local field) in order to cennect the data sets :
      localField: "_id", // the field where we store the data of foreign key we have gotten .
      foreignField: "tour", // the field where the tour's id is being stored .
      count: true
    });

also, I've included the schema options for all of my models:

    {
        toJSON: { virtuals: true }, // means I need the virual to be part of the output .
        toObject: { virtuals: true }, // mean I want it to be outputed as an obj .
      }

here I populate the reviews :

    exports.getTour = factory.getOne(Tour, {path: "reviews"});


    exports.getOne = (Model, popOp) => catchAsync( async(request, response, next) => {
    
        let query = Model.findById(request.params.id);
        // console.log(query);
        
        if(popOp) query = query.populate(popOp);
        const doc = await query;
    
        if(!doc) return next(new AppError(404,"No document is associated with this id"));
      
        response.status(200).json({
            status: "success",
            doc,
        });
    });

I've read Mongoose documentation many times it's the same as mine, couldn't figure out where is the problem in my implementation
I'm using:
"mongoose": "^7.3.4"
maybe the problem is caused by mongoDB by any chance ?