Check that Field Exists with MongoDB

Use $ne (for "not equal")

db.collection.find({ "fieldToCheck": { $ne: null } })

Suppose we have a collection like below:

{ 
  "_id":"1234"
  "open":"Yes"
  "things":{
             "paper":1234
             "bottle":"Available"
             "bottle_count":40
            } 
}

We want to know if the bottle field is present or not?

Ans:

db.products.find({"things.bottle":{"$exists":true}})

i find that this works for me

db.getCollection('collectionName').findOne({"fieldName" : {$ne: null}})