Database
[{"_id":"6032a5ad80443334a35f2232","List":[{"_id":"6032a5af80443334a35f2234","customData":[{"_id":"6032a5bc80443334a35f223c","systemUpdate_DT":null,"field_id":"6032a5bc80443334a35f223b"},{"_id":"6032a5c280443334a35f223e","systemUpdate_DT":null,"field_id":"6032a5c280443334a35f223d"}]},{"_id":"6032a5b080443334a35f2236","customData":[{"_id":"6032a5bc80443334a35f223c","systemUpdate_DT":null,"field_id":"6032a5bc80443334a35f223b"},{"_id":"6032a5c280443334a35f223e","systemUpdate_DT":null,"field_id":"6032a5c280443334a35f223d"}]}]}]
Query
db.collection.updateOne({{"List._id":mongodb.ObjectId(_id),"List.customData.field_id":mongodb.ObjectId(field_id)},{$set:{"List.$.customData.systemUpdate_DT":"updatedDTTM"}})