[{"patient":"patient1","description":"desc","assessments":[{"doctor":"doctor1","doa":"01-01-2020","slots":"slots1"},{"doctor":"doctor2","doa":"01-01-2020","slots":"slots2"},{"doctor":"doctor1","doa":"01-01-2020","slots":"slots3"}]},{"patient":"patient2","description":"desc","assessments":[{"doctor":"doctor1","doa":"01-01-2020","slots":"slots1"},{"doctor":"doctor1","doa":"01-01-2020","slots":"slots1"},{"doctor":"doctor3","doa":"01-01-2020","slots":"slots3"}]}]

db.collection.aggregate([{"$project":{"_id":0,"assessments":{"$filter":{"input":"$assessments","as":"as","cond":{"$eq":["$$as.doctor","doctor1"],"$eq":["$$as.slots","slots1"]}}}}}])