Mongoosejs virtual populate

Figured out what the problem was. By default, the virtual fields are not included in the output. After adding this in circle schema:

circleSchema.virtual('caregiver_details',{
    ref: 'caregiver',
    localField: 'caregivers',
    foreignField: 'userId'
});

circleSchema.set('toObject', { virtuals: true });
circleSchema.set('toJSON', { virtuals: true });

It now works perfectly.

If you use expressJs res.json method it's ehough to add only:

yourSchema.set('toJSON', { virtuals: true });

Or you can directly use toJSON/toObject:

doc.toObject({ virtuals: true })) // or doc.toJSON({ virtuals: true }))