How to find mongo `data(db.collection_name.find())` through express route and print the data into jade template.

Here is my express route( I am using express2.5.8)

```
    app.get('/showData',function(req,res){
  db.collection('comments',function(err, data){
    if(err){
      throw err;
    }
    else{
      data.find();
      res.render('help', {data: data});
    }
  });
});

```

It through an error that `db.collection` is not a function