How to query embedded documents in an embedded array mongodb

Question

I am starting out with mongodb and mongoose. This is what my db looks like

[
 {
  _id: "5fd0f98751e33831d8ef4899"
  date: "01/01/2020, 11:47:00 AM"
  groups: [
     {
       _id: "5fd0f98751e33831d8ef489a"
       name: "Eyob"
       profession: "doctor"
       posts: [
           { 
              _id: "5fd0f98751e33831d8ef489b"
              numberOfLikes: 16
              numberOfShares: "2 Shares"
           },
           { 
              _id: "5fd0f98751e33831d8ef489c"
              numberOfLikes: 26
              numberOfShares: "7 Shares"
           }
        
         ]
      },
      {
       _id: "5fd0f98751e33831d8ef489d"
       name: "Abel"
       profession: "teacher"
       posts: [
           { 
              _id: "5fd0f98751e33831d8ef489e"
              numberOfLikes: 16
              numberOfShares: "2 Shares"
           },
           { 
              _id: "5fd0f98751e33831d8ef489f"
              numberOfLikes: 26
              numberOfShares: "7 Shares"
           }    
         ]
      }

    ]

  },

  {
   _id: "5fd0f98751e33831d8ef489d"
   date: "01/02/2020, 11:47:00 AM"
   groups: [// an array of groups as the above one //]
  }
]

so for every groups array there is a group object that contains a posts array that contains a post object.('This might be confusing'). What I am trying to do is query a single post and also a single group using there unique ids. findById() returns null. Is there a way that I can query this objects using just there respective id's.

EraBoss · Accepted Answer · 2020-12-13 18:14:25Z

1

Try this, it should solve your issue.

(send a single-post _id to get your expected data)

const {id}=req.params;
YourDataModel.findOne({"groups.posts._id":id}, {"groups.posts._id.$":true})
.then(data=>data?res.send({
                     groupId:data.groups[0]._id, 
                     groupName:data.groups[0].name, 
                     post:data.groups[0].posts.filter(e=>e._id===id)[0]
            }): res.send("Not found!"))
.catch(err=>res.send(err))

You also can get all the posts of the group (relevant to that post) with the same code, just do res.send(data) or make necessary modification where necessary.

edited Dec 13, 2020 at 18:14

answered Dec 13, 2020 at 18:05

EraBoss

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1 Comment

EraBoss Over a year ago

Well, if it solves your issue, please mark the answer as a solution ( with the tick mark from where the answer starts)

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