[{"key":1,"localTimestamp":undefined,"exampleArray":[],"exampleField":false,"status":"active"},{"key":2,"localTimestamp":undefined,"exampleArray":["bla"],"exampleField":false,"status":"pending"},{"key":3,"localTimestamp":undefined,"exampleArray":[""],"exampleField":false,"status":"pending"}]

db.collection.update({status:"active"},{$set:{exampleField:"works",localTimestamp:new Date()},$addToSet:{agent:"007"}})