[{orderedItems:[{name:"product 1",qty:20,image:"image1",price:200,product:{type:"2222",ref:"Product",},},{name:"product 1",qty:40,image:"image2",price:300,product:{type:"333",ref:"Product",},},]},{orderedItems:[{name:"product 1",qty:30,image:"image1",price:200,product:{type:"2222",ref:"Product",},},{name:"product 2",qty:40,image:"image2",price:300,product:{type:"333",ref:"Product",},},]}]

db.collection.aggregate([{$unwind:"$orderedItems"},{$group:{_id:"$orderedItems.name",count:{$sum:"$orderedItems.qty"},},},])