Adding multiple key/values

Question

In my database.collection i.e. db.blog.posts I am trying to add a key and value that itself has multiple keys and values.

Current collection:

db.blog.posts.findOne()
"title":"blog posts"

I tried using $set, $push but nothing seems to work.

This also didn't work when I tried adding single collection:

db.blog.posts.updateOne({"title":"blog posts"}, {"$set":{"comments":[{"comment":"good post", "author":"john","votes":0}]}})

Nor insertOne instead of updateOne and I even tried with:

var myEmployee=[
{"comment":"good post", "author":"john", "votes":0},
{"comment":"i thought it was too short", "author":"claire","votes":3},
{"comment":"free watches", "author":"claire","votes":-1},
];
db.blog.posts.insert(myEmployee)

This is what I want:

"title" : "A blog post",
"comments" : [
    {
        "name" : "joe",
        "email" : "[email protected]",
        "content" : "nice post."
    },
    {
        "name" : "bob",
        "email" : "[email protected]",
        "content" : "good post."
    }
]

Geraint Anderson · Accepted Answer · 2019-06-03 14:11:24Z

1

The updateOne command you have should have created an array for comments with a single entry. If you wanted multiple entries, you can just add multiple objects to the array in the update. The $set operator will change the value of the key to what you set as the second parameter.

db['blog.posts'].updateOne({"title":"blog posts"}, {
  "$set": {
    "comments":[
      {
        "name" : "joe",
        "email" : "[email protected]",
        "content" : "nice post."
      },
      {
        "name" : "bob",
        "email" : "[email protected]",
        "content" : "good post."
      }
    ]
  }
})

If you want to add additional items to the comments, this can be done with $push. The $push operator adds to the array.

db['blog.posts'].updateOne({"title":"blog posts"}, {
  "$push": {
    "comments": {
      "comment": "good post",
      "author": "john",
      "votes": 0
    }
  }
})

Docs for $set
Docs for $push

NB the examples above are for a collection named 'blog.posts' rather than a database named 'blog' and a collection names 'posts'. Ideally, brackets should be used for the property accessor where the collection name is not a valid JavaScript identifier although the dot notation in the question still works.

edited Jun 3, 2019 at 14:11

answered Jun 3, 2019 at 13:19

Geraint Anderson

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1 Comment

Munish Gupta Over a year ago

ahhhhh...my mistake was i was adding square brackets after each sub key-value pairs and thanks for correcting that. Second problem was, i was not using the right code to display. To display multiple lines i was using db.blog.posts.findOne() instead of posts.find()

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