class TestDto

    {

        public string Name { get; set; }

        public int Age { get; set; }

        public List<string> Candidates { get; set; }

    }

    class TestModel

    {

        public string Name { get; set; }

        public int Age { get; set; }

        public List<CandidateModel> Candidates { get; set; }

    }

    class CandidateModel

    {

        public DateTime StartTime { get; set; }

        public string Candidate { get; set; }

    }

class Program

    {

        static void Main(string[] args)

        {

            var testModel = new TestModel()

            {

                Name = "Frankie",

                Age = ,

                Candidates = new List<CandidateModel>()

                {

                    new CandidateModel(){StartTime = new DateTime(, , , , , ), Candidate = "贝贝"},

                    new CandidateModel(){StartTime = new DateTime(, , , , , ), Candidate = "asan"},

                    new CandidateModel(){StartTime = new DateTime(, , , , , ), Candidate = "pangzi"}

                }

            };

            // DataTime.Now : {2018/10/21 21:51:12}

            testModel.Candidates = testModel.Candidates.Where(_ => _.StartTime < DateTime.Now).ToList();

            Mapper.Initialize(_ => _.CreateMap<TestModel, TestDto>()

                .ForMember(s => s.Candidates,

                    d => d.MapFrom(x => x.Candidates.Select(y => y.Candidate))));

            var testDto = Mapper.Map<TestDto>(testModel);

        }

    }