getBypage in Nested Array in MongoDB using Aggregate

Question

I am using mongoDB as backend server, I have nested array(one level array) like this

{
    "_id" : ObjectId("60b1fc6d3c43f74e0c1dba92"),
    "seriesId" : "60acebf73acb5b3a98d14331",
    "name" : "Season 1",
    "logoURL" : "uploads/season/1622277216401.png",
    "yearOfPublish" : "2021-05-29",
    "description" : "Season 1",
    "createdBy" : ObjectId("609cbf49ba46cc3924859ab5"),
    "createdOn" : "2021-05-29T08:33:49.480Z",
    "episode" : [ 
        {
            "seasonId" : "60b1fc6d3c43f74e0c1dba92",
            "name" : "Episode 1",
            "id" : 0,
            "logoURL" : "uploads/episode/1622278616899.png",
            "dateOfTelecast" : null,
            "description" : "sadfgh",
            "duration" : "30",
            "videoType" : "customURL",
            "embedCode" : "",
            "url" : "https://youtu.be/kbpsXMUr7ss",
            "liveboxChannel" : "",
            "createdOn" : "2021-05-29T08:56:59.230Z",
            "createdBy" : ObjectId("609cbf49ba46cc3924859ab5"),
            "_id" : "ZaVrpOLO5"
        }, 
        {
            "seasonId" : "60b1fc6d3c43f74e0c1dba92",
            "name" : "Episode 2",
            "id" : 0,
            "logoURL" : "uploads/episode/1622279206607.png",
            "dateOfTelecast" : null,
            "description" : "adfd",
            "duration" : "30",
            "videoType" : "customURL",
            "embedCode" : "",
            "url" : "https://youtu.be/kbpsXMUr7ss",
            "liveboxChannel" : "",
            "createdOn" : "2021-05-29T09:06:48.637Z",
            "createdBy" : ObjectId("609cbf49ba46cc3924859ab5"),
            "_id" : "9GKqXhxcH"
        },}

I have more no of seasons. from the season collection,i have episode array under the name of Episode.

Now My frontend page required that episode array alone.

response = {episode: all the episode data} and this episode data is based on skip and limit value

I have tried something in mongodb,

db.getCollection('season_copy').aggregate([
{$project: {
        episodes: {
          $cond:{ if: { $isArray: "$episode" }, then: { input:"$episode" }, else: 0 }
        },
      },
    },
  ])

Can anyone suggest me some idea?

Answer 1

Check this out:

Without aggregate:

db.getCollection('season_copy')
.find({ _id: ObjectID(id)})
.project({ episode: 1 }).toArray();

With aggregate:

MongoDB playground

db.getCollection('season_copy')
.aggregate([
  {
    $match: {
      _id: ObjectId("60b1fc6d3c43f74e0c1dba92")
    }
  },
  {
    $project: {
      episode: 1
    }
  }
])