[{_id:"1",val:"admin"},{_id:"2",val:"employee"},{_id:"3",val:"admin"}]

db.collection.update({},[{"$set":{"val":{"$cond":{"if":{"$or":[{"$eq":["$val","admin"]},{"$eq":["$val","employee"]}]},"then":{"$concat":["$val","-en"]},"else":"$val"}}}}],{"multi":true})