Update an object in nested array in MongoDB

Hello Reader 👋

To update an object inside a nested array in MongoDB you can use this approach, Its well tested and working.

Case:

Update nested array objects. See below picture for a better Idea what we are going to do. We will update the object which is nested by 3 levels of array.

{
 discussionList[
  discussionList [
   {
     object-value-to-be-updated.
   }
  ]
 ]
}

Solution:

public courseCategoryPostCommentReplyUpdate(operation: CommentReplyUpdateMutation): Promise<IDocumentUpdateType> {
    return this.courseCategoryPostCommentsModel.updateOne(
      {
        "postId" : operation.postId,
        'discussionList': {
          '$elemMatch': {
            '_id': operation.commentId,
            "discussionList._id": operation.replyId
          }
        }
      },
      {
        $set: {
          "discussionList.$[outer].discussionList.$[inner].payload": operation.payload,
          "discussionList.$[outer].discussionList.$[inner].isUpdated": true,
          "discussionList.$[outer].discussionList.$[inner].commentUpdateTime": new Date()
        }
      },
      {
        arrayFilters: [
          { "outer._id": operation.commentId},
          {"inner._id": operation.replyId}

      ]
      }
    );
  }

FootNotes - this code is to update the reply of a comment.

That's how you can perform operations on an object in nested array in mongoDB document. You can also update/delete the objects which are having the more level of nesting by just modifying the query.

Please let me know if the code needs an explanation. Thanks 🙂