Use $gte and &lte mongo operator if date is in string format in mongodb

Question

I have dob field like {dob:"02-23-2000"} in database. Now I want to perform $gte and &lte on dob field that is in string format like below:

db.panelists.count({"dob":{ '$gte': '08-02-1998', '$lte': '08-02-2003' }});

I am getting count value as zero always.

Could anyone please help me out to resolve this query in same dob format.

Solution

You can try below aggregation in mongodb 3.6

You can use $dateFromString aggregation to convert your dob from string to date and then easily $count the documents applying $match on it.

1) Using aggregation with $addFields

db.panelists.aggregate([
  { "$addFields": {
    "date": {
      "$dateFromString": { "dateString": "$dob", "format": "%m-%d-%Y" }
    } 
  }},
  { "$match": {
    "date": {
      "$gte": moment('08-02-1998').toDate(),
      "$lte": moment('08-02-2003').toDate()
    }
  }},
  { "$count": "count" }
])

2) Using simple find query with $expr

db.collection.find({
  "$expr": {
    "$and": [
      {
        "$gte": [
          { "$dateFromString": { "dateString": "$dob", "format": "%m-%d-%Y" }},
          ISODate("2000-02-22T00:00:00Z")
        ]
      },
      {
        "$lte": [
          { "$dateFromString": { "dateString": "$dob", "format": "%m-%d-%Y" }},
          ISODate("2000-02-24T00:00:00Z")
        ]
      }
    ]
  }
})

3) Using aggregation with $expr

db.collection.aggregate([
  { "$match": {
    "$expr": {
      "$and": [
        {
          "$gte": [
            { "$dateFromString": { "dateString": "$dob", "format": "%m-%d-%Y" }},
            ISODate("2000-02-22T00:00:00Z")
          ]
        },
        {
          "$lte": [
            { "$dateFromString": { "dateString": "$dob", "format": "%m-%d-%Y" }},
            ISODate("2000-02-24T00:00:00Z")
          ]
        }
      ]
    }
  }}
])