db={"coll":[{_id:"5df1e6f75de2b22f8e6c30e8",user:{name:"Tom",sex:1,age:23},dream:[{label:"engineer",industry:"5e06b16fb0670d7538222909",type:"5e06b16fb0670d7538222951",},{label:"programmer",industry:"5e06b16fb0670d7538222909",type:"5e06b16fb0670d7538222951",}],works:[{name:"any engineer",company:"5dd7fd51b0ae1837a08d00c8",skill:["5dc3998e2cf66bad16efd61b","5dc3998e2cf66bad16efd61e"],},{name:"any programmer",company:"5dd7fd9db0ae1837a08d00e2",skill:["5dd509e05de2b22f8e67e1b7","5dd509e05de2b22f8e67e1bb"],}]}],"industry":[{_id:"5e06b16fb0670d7538222909",name:"IT",createdAt:"2019-12-28T01:35:44.070Z",updatedAt:"2019-12-28T01:35:44.070Z"}],"type":[{_id:"5e06b16fb0670d7538222951",name:"job",createdAt:"2019-12-28T01:35:44.070Z",updatedAt:"2019-12-28T01:35:44.070Z"}],"company":[{_id:"5dd7fd51b0ae1837a08d00c8",name:"alibaba",area:"CN",},{_id:"5dd7fd9db0ae1837a08d00e2",name:"microsoft",area:"EN",},],"skill":[{_id:"5dc3998e2cf66bad16efd61b",},{_id:"5dc3998e2cf66bad16efd61e",name:"Php"},{_id:"5dd509e05de2b22f8e67e1b7",name:"Golang"},{_id:"5dd509e05de2b22f8e67e1bb",name:"Node.js"}]}

db.coll.aggregate([{$unwind:{path:"$dream",}},{$lookup:{from:"industry",localField:"dream.industry",foreignField:"_id",as:"dream.industry"},},{$unwind:{path:"$dream.industry",}},{$lookup:{from:"type",localField:"dream.type",foreignField:"_id",as:"dream.type"},},{$unwind:{path:"$dream.type",}},{$unwind:{path:"$works",}},{$lookup:{from:"company",localField:"works.company",foreignField:"_id",as:"works.company"},},{$unwind:{path:"$works.company",}},{$lookup:{from:"skill",localField:"works.skill",foreignField:"_id",as:"works.skill"},},])