[{"collection":"collection","count":10,"content":{"samples":[{id:1,name:"sample1",active:true,},{id:2,name:"sample2",active:true,},{id:3,name:"sample3",active:false,},{id:4,name:"sample4",active:false,},{id:5,name:"sample5",active:true,},{id:6,name:"sample6",active:true,}]}}]

db.collection.aggregate({$project:{"samples":{$filter:{input:{$map:{input:{$zip:{inputs:[{$range:[0,{$size:"$content.samples"}],},"$content.samples"]},},as:"c",in:{"_idx":{$arrayElemAt:["$$c",0],},"_content":{$arrayElemAt:["$$c",1],}}}},as:"d",cond:"$$d._content.active"}}}})