User.js

// define the schema for our user model
var userSchema = mongoose.Schema({

    local            : {
        first_name   : String,
        last_name    : String,
        email        : String,
        password     : String,
    },
    facebook         : {
        id           : String,
        token        : String,
        email        : String,
        name         : String
    },
    twitter          : {
        id           : String,
        token        : String,
        displayName  : String,
        username     : String
    },
    google           : {
        id           : String,
        token        : String,
        email        : String,
        name         : String
    }

});