Adding data to database only when it is not already present (Node js)

Im trying to add new data to database ,only if it isn't already present.I ask user to enter name ,and if the name already exists he/she can't enter corresponding data,and an error is to be shown saying it "already exists". This is what im doing-

app.post("/new",function(req,res){
    Model.findOne({"name":req.body.name},function(err,persons){
         if(err!=null)
            { req.flash("error","Already Exists");
              res.redirect("/new");}
         if(err==null)
            { Model.create(req.body.person,function(err,newPerson){
                    if(err){console.log("Error");}
                    else{
                    newPerson.name=req.user.name;
                    newPerson.id=req.user._id;
                    newPerson.save();
                    res.redirect("/");}

            });}
    });

});

But when i use this,even though i enter already present data,it still adds it to the database. Im using express,node js and mongodb

via Ravi Hooda