Adding multiple key/values - mongodb

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" : "joe#example.com",
"content" : "nice post."
},
{
"name" : "bob",
"email" : "bob#example.com",
"content" : "good post."
}
]

Answer 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" : "joe#example.com",
"content" : "nice post."
},
{
"name" : "bob",
"email" : "bob#example.com",
"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.