Update in array in Mongodb

Question

{
    "_id" : "55dcb404478e7227203d3a65",
    "Nome" : "Grupo Familia",
    "Pessoas" : [ 
        {
            "PessoaId" : "55dcb425478e72207833e970",
            "Nome" : "Carlos",
            "Habilidades" : [
                {
                    "HabilidadeId" : "55dcb433478e7229b0e3ee07",
                    "Nome": "Pular",
                    "Macetes": [
                            {"Descricao" : "Usar um tênis macio"},
                            {"Descricao" : "Se alongar"}
                    ]
                },
                {
                    "HabilidadeId" : "55dcb425478e72207833e961",
                    "Nome" : "Correr"
                }
            ],
        }
    ],
}

I have this Collection on Mongodb and I have the following question: How do I add a new skill trick "correr" ?

Answer 1

You must use the $addToSet or the $push. The difference is whether you want unique elements in the array or not.

There is a positional operator $ that you can use to update elements in the index that matches your query. So, if you "know" that there is a skill but don’t know its position, you should do the following query:

db.grupos.update({ _id: "...", "Pessoas.Habilidades.Nome": "Correr" }, {
  "$addToSet": {
    "Pessoas.$.Habilidades.$.Macetes": { /*...*/ }  
  }
})

If you want to remove elements, you need to use $pull and to add/remove more than one element you will need to use $each.

Useful links:

• http://docs.mongodb.org/manual/reference/operator/update/addToSet/

• http://docs.mongodb.org/manual/reference/operator/update/push/

• http://docs.mongodb.org/manual/reference/operator/update/pull/

• https://docs.mongodb.org/manual/reference/operator/update/each/

I suggest an index in Pessoas.Habilidades.Nome.

EDIT

I just researched a little more and what you want to do is not possible:

• http://docs.mongodb.org/manual/reference/operator/update/positional/#nested-arrays

Of documentation:

The $ positional operator cannot be used for searches that traverse more than one array, as the searches that traverse arrays "nested" in other arrays, because the substitution by the $ placeholder is a single value

It is necessary to change the way the data is modeled. Or lose the operation atomicity.

Answer 2

You can use $set. Example:

db.bla.update({"_id":"55dcb404478e7227203d3a65"},
{
    "$set": {
        "Pessoas.0.Habilidades.1.Macetes": [
            {
                "HabilidadeId": "idnovo",
                "Nome": "Pular"
            }
        ]
    }
})