How to insert document into a collection with only one ObjectID using Mongoose?

Question

How to insert document into a collection with only one ObjectID using Mongoose?

I have a JSON which I want to store in collection using Mongoose. Function that I am using to insert the document into collection is :

UserSchema.statics.SaveDocument=function(docs,callback){
    docs=JSON.parse(docs);    
    this.create(docs,function(err,data){
        if(err) callback(err);
        else callback(data);
    });
};

Schema for the collection is :

var UserSchema   = new Schema({
    A : String,
    B : String,
    C : [
        {
            D : Schema.Types.ObjectId,
            E : String,
        }
    ]
});

The JSON format which I am trying to store is like :

{
    "A" : "something",
    "B" : "something",
    "C" : [
            {
                    "D" : "something",
                    "E" : "Something",
            }
    ],
}

and the document being stored into collection looks like :

    {
    "_id" : ObjectId("55XXXXX"),
    "A" : "something",
    "B" : "something",
    "C" : [
            {
                    "D" : "something",
                    "E" : "Something",
                    "_id" : ObjectId("56XXXXX"),
            }
    ],
    "__v" : 0
}

Now, what I want is to store the ObjectId being generated by my funtion and not to to store that additional ObjectID that mongoose is inserting in the array of element C.
I know that by using { id: false } in function I can disable autogenerated ID but I can't use that for that unnecessary ID inserted by mongoose in C because that eliminates both ObjectID .
So can someone help me how I can do this ?
Another thing is I don't have any Idea where from "__V": 0 is coming into the collection ?

json
node.js
mongodb
express
mongoose

Answer 1

For __V part: You can disable it by appending { versionKey: false } see: http://mongoosejs.com/docs/guide.html#versionKey

To remove that _id in C you can define a subschema like

var C = mongoose.Schema({
    //C schema content
},{ _id : false });

and change your original schema to something like :

var UserSchema   = new Schema({
    A : String,
    B : String,
    C : [subSchema] ....
...)};

Then try inserting the new doc.

Answer 2

It can also be done by adding _id : false in element C of Schema:

var UserSchema   = new Schema({
    C : [
        {
            D : Schema.Types.ObjectId,
            E : String,
            _id : false
        }
    ]
});

Sub schema helps you when you have more than one schema using same sub structure, but here I only have one schema so using sub schema does not sense good.