小编Phi*_*ski的帖子

如何在$ lookup之后添加过滤器,还是有其他方法可以执行此操作？

我的数据收集测试是:

{ "_id" : ObjectId("570557d4094a4514fc1291d6"), "id" : 100, "value" : "0", "contain" : [ ] }
{ "_id" : ObjectId("570557d4094a4514fc1291d7"), "id" : 110, "value" : "1", "contain" : [ 100 ] }
{ "_id" : ObjectId("570557d4094a4514fc1291d8"), "id" : 120, "value" : "1", "contain" : [ 100 ] }
{ "_id" : ObjectId("570557d4094a4514fc1291d9"), "id" : 121, "value" : "2", "contain" : [ 100, 120 ] }

我选择id 100并聚合孩子:

db.test.aggregate([ {
  $match : {
    id: 100
  }
}, {
  $lookup …