using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

public class Program

{   

    public static void Main()

    {

        List<Hospital> hospitals = new List<Hospital>

        {

            new Hospital {

                HospitalId = 1,

                Phone = "5555555566"

            },

            new Hospital {

                HospitalId = 2,

                Phone = "5555555567"

            },

            new Hospital {

                HospitalId = 3,

                Phone = "5555555568"

            },

            new Hospital {

                HospitalId = 4,

                Phone = "5555555577"

            },

            new Hospital {

                HospitalId = 5,

                Phone = "5555555576"

            },

            new Hospital {

                HospitalId = 6,

                Phone = "5555555886"

            },

            new Hospital {

                HospitalId = 7,

                Phone = "5555555599"

            },

            new Hospital {

                HospitalId = 8,

                Phone = "5555555456"

            },

        };

        List<Hospital> fetched = new List<Hospital>

        {

            new Hospital {

                HospitalId = 2,

                Phone = "5555555566"

            },

            new Hospital {

                HospitalId = 9,

                Phone = null

            },

            new Hospital {

                HospitalId = 1,

                Phone = "5555555566"

            },

        };

        var result = hospitals

                .Select(h => new Hospital { HospitalId = h.HospitalId, Phone = h.Phone })

                .Except(fetched, new HospitalEqualityComparer())

                .ToList();

        var hospitalsResult = hospitals

            .Where(h => result.Select(r => r.HospitalId).Contains(h.HospitalId))

            .ToList();

        //using (var writer = new System.IO.StringWriter()) 

        //{

        //  ObjectDumper.Dumper.Dump(result, "Result", writer);

        //}

        string json = JsonConvert.SerializeObject(result, Formatting.Indented);

        string json2 = JsonConvert.SerializeObject(hospitalsResult, Formatting.Indented);

        Console.WriteLine(json);

        Console.WriteLine(json2);

    }

}

​

public class HospitalEqualityComparer: IEqualityComparer<Hospital>

{

    public bool Equals(Hospital f1, Hospital f2) {

        if (f1 == null && f2 == null)

            return true;

        else if (f1 == null || f2 == null)

            return false;

        else if (f1.HospitalId == f2.HospitalId && f1.Phone == f2.Phone)

            return true;

        else return false;

    }

    public int GetHashCode(Hospital f1)

    {

        if (Object.ReferenceEquals(f1, null)) return 0;

        int hashFetchPhone = f1.Phone == null ? 0 : f1.Phone.GetHashCode();

        int hashFetchId = f1.HospitalId.GetHashCode();

        return hashFetchPhone ^ hashFetchId;

    }

}

​

public partial class Hospital

{

    public int HospitalId { get; set; }

    public string Phone { get; set; }

}

​