In case I have a multiselect in html,and I want to separate the selected values within the combobox and separate by commas when I list all users with their replies types of requests.
  public IEnumerable<UserDataModel> Get()
    {
        UserDataModel userModel = new UserDataModel();
        //var reg = ctx.User.Include(x => x.Area.Name).Include(x =>x.RequestType);
        var users = ctx.User.OrderBy(u => u.Name).Select(u => new 
                        UserDataModel
        {
            typesModel = u.RequestType.Select(x => new RequestTypeModel
            {
                Id = x.IdRequestType,
                Name = x.Name
            }).ToList()
        }).ToList();
        foreach (var user in users)
        {
            var strTypesModel = "";
            foreach (var typesModel in user.typesModel)
            {
                strTypesModel = strTypesModel + typesModel.Name;
                user.TypesModelAggregate = string.Join(",", user.typesModel);
            }
        }
     return users;
    }
							
							
						 
user.Typesmodelaggregate = string. Join(",", user.typesModel);
– Gustavo Santos