i am stuck with same case where i am trying to do a lookup with same collection as ben but i have the fruit_name fields already as an empty array [].
but it doesnt returns the another document
my aggregate query
db.child_fruits.aggregate([
{ $match: {
_id: ObjectId(‘624c577bc98e24f398b012ad’)
}
},
{ $lookup: {
from: ‘fruit’,
localField: ‘fruit_name’,
foreignField: ‘name’,
as: ‘fruitDetails’
}
},
{ $unwind: { path: ‘$fruitDetails’ } }
])