Database
[{userId:"1",userName:"abc",activites:[{activityId:"001",name:"fddfdfd",points:"10"},{activityId:"002",name:"fddfdfd",points:"15"}]}]
Query
db.collection.update({},[{"$set":{"activites":{$map:{input:"$activites",as:"item",in:{activityId:"$$item.activityId",points:"$$item.points",name:{$switch:{branches:[{case:{$eq:["$$item.activityId","001"]},then:"run"},{case:{$eq:["$$item.activityId","002"]},then:"walk"},],default:"$$item.name"}}}}}}}],{multi:true})