how to create a partial index with $exists: false condition?

Question

I want to create this partial index:

db.mycollection.createIndex( 
  {"firstname": 1, "lastname": 1}, 
  { partialFilterExpression: { "status": {$exists: false}, "quantity": { $lt: -1 } } } ); 

but i receive this error:

unsupported expression in partial index: $not\n status exists\n"

How can I do ?

Answer 1

Unfortunately, you don't.

That feature request has been around for quite a while: https://jira.mongodb.org/browse/SERVER-17853

Hopefully they get to it soon, that would be quite useful.

Answer 2

If the status field doesn't have null values, you can use

{ partialFilterExpression: { "status": null, "quantity": { $lt: -1 } } } );