I have a situation where i need to get the dates between specific dates and also get the dates which are not thr (meaning which are empty)

Below is the way of query that am presuming to work like, please help me get corrected.

```
EvaluationTraining.find({
    mnguser: userid,
    evalDate: "", //i want the empty ones too
    evalDate: {
        '$gte': firstDay,
        '$lte': lastDay
    }
    })
    .sort({evalDate: 'desc'})
    .then(function(eval){
      //results
    })
    .catch(function(err){
      //err
    })

```

Thanks in advance