nodejs: How generate schema.pre('save',...) unique field

I have user registration on mongoose and I need to generate unique random ident field from possible values. The problem is I can not query to mongodb.

The result of script in console is "ONE". That's it. So, where is mistake? And is there better way to generate unique random field/number?

schemaUser.pre('save', function (next) {

    var self = this;

    function genIdent() {
        var ident = "", possible = "013456789";

        for(var i=1; i <= 5; i++)
            ident += possible.charAt(Math.floor(Math.random() * possible.length));

        return ident;
    }

    function doIt() {
        var ident = genIdent();

        console.log('ONE');

        mongoose.model('User', schemaUser).findOne({ident: ident}, function(err, o) {
            console.log('TWO');
            if (o) {
                doIt();
            } else {
                self.ident = ident;
                next();
            }
        });

    }

    doIt();

});