Question

Lets say I have a collection with two documents in…

{"_id": ..., "msg": "hello world"}
{"_id": ..., "name": "bob dylan"}

and a query…

db.collection.find({}, {"text": 1})

Why does this return both documents? Is there a way to return only when the msg field exists?

Answer 1

Your query returns both documents because your criteria is empty ({}):

db.collection.find({}, {"text": 1})

If you only want to find documents where the msg field exists, you can use $exists:

db.collection.find({ msg: { $exists: true}}, { "text" : 1 })

Note that for the second parameter to find(), you are only requesting the value of the text field to be displayed.