How do I prepend an object to the top position of an array?

Question

If I have the following array in a MongoDb doc:

"example": {
    [
        "number": 5,
        "someValue": "V"
    ],
    [
        "number": 7,
        "someValue": "H"
    ]
}

How would i add the array below to the top of the one above:

[
     "number": 3,
     "someValue": "S"
]

So that the original array becomes:

"example": {
    [
        "number": 3,
        "someValue": "S"
    ],
    [
        "number": 5,
        "someValue": "V"
    ],
    [
        "number": 7,
        "someValue": "H"
    ]
}

Answer 1

you can achieve this with the options of the $push operator like this :

db.collection.update({},
{  
   $push:{  
      "arr":{  
         $each:[  
            {  
               "number": 3,
               "someValue": "S"
            }
         ],
         $position: 0
      }
   }
})

the $position specify where the element will be inserted.