As a beginner in software, I am trying to learn MongoDb, but there is a subject I need help with:
I want to see the license plate codes of the neighboring cities and the names of the cities in the information of the city I have selected in my project. For this, I need to use the .Match() and .Lookup() methods as a result of some research. When I try these results, I keep getting syntax errors. I am not sure if the structure I have set up is correct. Thank you for your help.

    public class RelationalCityViewModel
    {
        [BsonId]
        public ObjectId Id { get; set; }
        public string PlakaCode { get; set; }
        public string Name { get; set; }
        public int OrderNo { get; set; }
        public bool IsDelete { get; set; }
        public int CountryId { get; set; }
        public string Url { get; set; }
        public List<NeighborCity> NeighborCities { get; set; }
    }

 public class RelationalCityCreateViewModel
 {
     public string PlakaCode { get; set; }
     public string Name { get; set; }
     public int OrderNo { get; set; }
     public int CountryId { get; set; }
     public string Url { get; set; }
     public List<NeighborCity> NeighborCities { get; set; }
 }

 public class NeighborCity
 {
     [BsonId]
     public ObjectId Id { get; set; }
     public string PlakaCode { get; set; }
     public string Name { get; set; }
     public bool IsDelete { get; set; }
 }

 public async Task<BsonDocument> GetDataByIdWithFilter(FilterDefinition<BsonDocument>? filter, ObjectId id, RelationalCityViewModel relationalCityViewModel)
 {
     var result = _mongoDbCollection.Aggregate()
                     .Match(filter)
                     .Lookup(_mongoDbCollection,
                             relationalCityViewModel.NeighborCities.FirstOrDefault().Id,
                             relationalCityViewModel.Id,
                             (RelationalCityViewModel city, IEnumerable<RelationalCityViewModel> neighbors) => new
                             {
                                 city.Name,
                                 city.PlakaCode,
                                 NeighborCities = neighbors.Select(n => new
                                 {
                                     n.Name,
                                     n.PlakaCode
                                 })
                             }
                     );


     return result;
 }