using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""albums"": {

                ""data"": [

                  {

                    ""name"": ""Album 1"",

                    ""photos"": {

                      ""data"": [

                        {

                          ""id"": ""686123475970""

                        },

                        {

                          ""comments"": {

                            ""data"": [

                              {

                                ""from"": {

                                  ""name"": ""John Smith"",

                                  ""id"": ""10206512123464061""

                                },

                                ""message"": ""Test Comment 1 string value"",

                                ""id"": ""1571234466083854""

                              }

                            ],

                            ""paging"": {

                              ""cursors"": {

                                ""before"": ""WTI5dGJXVnVkRjlqZAFhKemIzSTZANVFUzTlRVNU1EUTJOakE0TXpnMU5Eb3hORGN6TkRZAMk5EWTQZD"",

                                ""after"": ""WTI5dGJXVnVkRjlqZAFhKemIzSTZANVFUzTlRVNU1EUTJOakE0TXpnMU5Eb3hORGN6TkRZAMk5EWTQZD""

                              }

                            }

                          },

                          ""id"": ""686203123490""

                        },

                        {

                          ""id"": ""686212345870""

                        },

                        {

                          ""id"": ""612343620880""

                        },

                        {

                          ""comments"": {

                            ""data"": [

                              {

                                ""from"": {

                                  ""name"": ""Ken Johnson"",

                                  ""id"": ""1720261242234464""

                                },

                                ""message"": ""I like this photo"",

                                ""id"": ""1029357829789345""

                              },

                              {

                                ""from"": {

                                  ""name"": ""Jim Robertson"",

                                  ""id"": ""21217623234575172""

                                },

                                ""message"": ""This here is another test comment"",

                                ""id"": ""1672244567093955""

                              }

                            ],

                            ""paging"": {

                              ""cursors"": {

                                ""before"": ""WTI5dGJXVnVkRjlqZAFhKemIzSTZANVFUzTlRVNU1EUTJOakE0TXpnMU5Eb3hORGN6TkRZAMk5EWTQZD"",

                                ""after"": ""WTI5dGJXVnVkRjlqZAFhKemIzSTZANVFUzTlRVNU1EUTJOakE0TXpnMU5Eb3hORGN6TkRZAMk5EWTQZD""

                              }

                            }

                          },

                          ""id"": ""612343615890""

                        },

                        {

                          ""id"": ""686203123430""

                        }

                      ]

                    }

                  },

                  {

                    ""name"": ""Album 2"",

                    ""photos"": {

                      ""data"": [

                        {

                          ""id"": ""686988765970""

                        },

                        {

                          ""id"": ""617837582080""

                        },

                        {

                          ""comments"": {

                            ""data"": [

                              {

                                ""from"": {

                                  ""name"": ""John Smith"",

                                  ""id"": ""10206512123464061""

                                },

                                ""message"": ""Blah blah blah nothing to see here"",

                                ""id"": ""1496736878083876""

                              },

                              {

                                ""from"": {

                                  ""name"": ""Fred Jones"",

                                  ""id"": ""1976365234643531""

                                },

                                ""message"": ""The only way to know if something works is to test it."",

                                ""id"": ""1571234958398554""

                              }

                            ],

                            ""paging"": {

                              ""cursors"": {

                                ""before"": ""WTI5dGJXVnVkRjlqZAFhKemIzSTZANVFUzTlRVNU1EUTJOakE0TXpnMU5Eb3hORGN6TkRZAMk5EWTQZD"",

                                ""after"": ""WTI5dGJXVnVkRjlqZAFhKemIzSTZANVFUzTlRVNU1EUTJOakE0TXpnMU5Eb3hORGN6TkRZAMk5EWTQZD""

                              }

                            }

                          },

                          ""id"": ""622436753490""

                        },

                        {

                          ""id"": ""685786894421""

                        }

                      ]

                    }

                  }

                ]

              }

            }";

        RootObject root = JsonConvert.DeserializeObject<RootObject>(json);

        var comments = GetComments(root, "test");

​

        Console.WriteLine(string.Join("\r\n", comments));

    }

    public static List<string> GetComments(RootObject root, string keyword)

    {

        return root.albums.data

            .SelectMany(a => a.photos.data, (a,p) => new { Album = a.name, Comments = p.comments })

            .Where(p => p.Comments != null)

            .SelectMany(p => p.Comments.data, (p,c) => new { Album = p.Album, From = c.from, Message = c.message })

            .Where(c => c.Message.IndexOf(keyword, StringComparison.OrdinalIgnoreCase) >= 0)

            .Select(c => c.From.name + " - " + c.Album + " - " + c.Message)

            .ToList();

    }

​

}

​

public class From

{

    public string name { get; set; }

    public string id { get; set; }

}

​

public class Datum3

{

    public From from { get; set; }

    public string message { get; set; }

    public string id { get; set; }

}

​

public class Cursors

{

    public string before { get; set; }

    public string after { get; set; }

}

​

public class Paging

{

    public Cursors cursors { get; set; }

}

​

public class Comments

{

    public List<Datum3> data { get; set; }

    public Paging paging { get; set; }

}

​

public class Datum2

{

    public string id { get; set; }

    public Comments comments { get; set; }

}

​

public class Cursors2

{

    public string before { get; set; }

    public string after { get; set; }

}

​

public class Paging2

{

    public Cursors2 cursors { get; set; }

}

​

public class Photos

{

    public List<Datum2> data { get; set; }

    public Paging2 paging { get; set; }

}

​

public class Datum

{

    public string name { get; set; }

    public Photos photos { get; set; }

    public string id { get; set; }

}

​

public class Cursors3

{

    public string before { get; set; }

    public string after { get; set; }

}

​

public class Paging3

{

    public Cursors3 cursors { get; set; }

}

​

public class Albums

{

    public List<Datum> data { get; set; }

    public Paging3 paging { get; set; }

}

​

public class RootObject

{

    public Albums albums { get; set; }

    public string id { get; set; }

}

​