I'm dynamically constructing and modifying a query in code.
I want a certain codepath to have the Collection return 0 documents.
I simply do Collection.find({_id:null}) . This seems to work.
Just wondering if there was a more standard way to do this in MongoDB. Thanks!
null is a valid value for _id, so while that query may be fine for your data, in general it's not guaranteed to produce the empty result set:
MongoDB Enterprise > db.foo.insert({_id:null})
WriteResult({ "nInserted" : 1 })
MongoDB Enterprise > db.foo.find()
{ "_id" : null }
MongoDB Enterprise > db.foo.find({_id:null})
{ "_id" : null }
MongoDB Enterprise >
_id however does need to be present in each document, therefore a query insisting it isn't present should always return the empty result set:
db.foo.find({_id:{$exists:false}})
This only works for queries on top-level documents, naturally.
null is fine for my data because there's validation on _id. But your solution is airtight. thanks