db={"fridges":[{_id:1,items:[{itemId:1,name:"beer"},{itemId:2,name:"chicken"}],brand:"Bosch",size:195,cooler:true,color:"grey"},{_id:2,items:[{itemId:1,name:"beer"},{itemId:2,name:"chicken"},{itemId:3,name:"lettuce"}],brand:"Electrolux",size:200,cooler:true,color:"white"},]}

db.fridges.aggregate([{"$match":{$and:[{"brand":{$in:["Bosch","Samsung"]}},{"color":{$in:["grey","white"]}}]}},{"$project":{"itemsNumber":{$size:"$items"},brand:1,cooler:1,color:1}}])