' https://dotnetfiddle.net/Fw3myB

Imports System

Imports System.Linq

Imports System.Collections

Imports System.Collections.Generic

Imports System.IO

Imports System.Xml.Linq

Imports System.Xml

Imports System.Text

Imports System.Text.RegularExpressions

​

Imports Newtonsoft.Json

Imports Newtonsoft.Json.Linq

Imports Newtonsoft.Json.Converters

Imports Newtonsoft.Json.Serialization

​

Imports NUnit.Framework

​

    ' https://stackoverflow.com/questions/74027865/read-single-row-and-attributes-from-huge-json-file-via-jsontextreader

​

Public Module JsonExtensions

    Iterator Function DeserializeItemsByPath(Of T)(ByVal stream As Stream, regex as Regex, ByVal Optional settings As JsonSerializerSettings = Nothing) As IEnumerable(Of T)

        Using textReader = New StreamReader(stream, Encoding.UTF8, true, 1024, true)

            For Each item as T In DeserializeItemsByPath(Of T)(textReader, regex, settings)

                Yield item

            Next

        End Using

    End Function

​

    ' Adapted from this answer https://stackoverflow.com/a/56411253/3744182

    ' By https://stackoverflow.com/users/14357/spender

    ' To https://stackoverflow.com/questions/43747477/how-to-parse-huge-json-file-as-stream-in-json-net

    Iterator Function DeserializeItemsByPath(Of T)(ByVal textReader As TextReader, ByVal regex as Regex, ByVal Optional settings As JsonSerializerSettings = Nothing) As IEnumerable(Of T)

        Dim serializer = JsonSerializer.CreateDefault(settings)

        Using reader = New JsonTextReader(textReader) With { .CloseInput = False }

            While reader.Read()

                If reader.TokenType <> JsonToken.PropertyName And regex.IsMatch(reader.Path)

                    Yield serializer.Deserialize(Of T)(reader)

                End If

            End While

        End Using

    End Function

End Module

​

Friend Class ListingsIntermediateDTO

    Property publishdate As String

    Property facilities as JToken

End Class

​

Public Class ListingsDTO

    ' kindLabel

    Property publishdate As String

    ' .totalSize.value

    Property totalSizeValue as Decimal?

    ' .bedrooms.value

    Property bedroomsValue as Decimal?

End Class

​

Public Class TestClass  

    Shared Friend Sub Test()

        For Each jsonString in GetJson()

            Test1(jsonString)

            Console.WriteLine()

        Next

    End Sub

​

    Shared Friend Sub Test1(ByVal json As String)

        Dim fileName = "Question74027865.json"

        File.WriteAllText(fileName, json)

​

        For Each value in GetListings(fileName)

            Console.WriteLine("result: {0}", JsonConvert.SerializeObject(value))

        Next

​

        File.Delete(FileName)

    End Sub

​

    Public Shared Iterator Function GetListings(ByVal fileName as String) as IEnumerable(Of ListingsDTO)

        Using stream = File.OpenRead(FileName)

            Dim regex as Regex = new Regex("^(listings\[[0-9]+\]|\[[0-9]+\])$", _

                                           RegexOptions.CultureInvariant Or RegexOptions.Compiled Or RegexOptions.Singleline)

            Console.WriteLine(regex)

            For Each value in _

                JsonExtensions.DeserializeItemsByPath(Of ListingsIntermediateDTO)(stream, regex) _

                    .Select(Function(dto) new ListingsDTO With { 

                        .publishdate = dto.publishdate, 

                        .totalSizeValue = dto.facilities.SelectTokens("totalSize.value").Select(Function(t) t.ToObject(Of Decimal?)()).FirstOrDefault(),

                        .bedroomsValue = dto.facilities.SelectTokens("bedrooms.value").Select(Function(t) t.ToObject(Of Decimal?)()).FirstOrDefault()

                    })

                Yield value

            Next

        End Using

    End Function 

    Shared Function GetJson() as IEnumerable(Of String)

        Dim array = { <![CDATA[

{

   "generatedAt":"2022-05-02 02:03:25",

   "listings":[

      {

         "countryid":1,

         "publishdate":"2022-04-02 02:03:25",

         "location":{

            "neighborhood":"Finthen",

            "city":"Mainz",

            "country":"Germany"

         },

         "facilities":{

            "bedrooms":{

               "value":2

            },

            "totalSize":{

               "value":"100"

            }

         }

      },

      {

         "countryid":2,

         "publishdate":"2022-02-02 02:03:24",

         "location":{

            "neighborhood":"Ubers",

            "city":"NYC",

            "country":"USA"

         },

         "facilities":{

            "bedrooms":{

               "value":3

            },

            "totalSize":{

               "value":"150"

            }

         }

      }

   ],

   "count":1077

}

]]>.Value, _

<![CDATA[

[

   {

      "publishdate":"2022-04-02 02:03:25",

      "countryid":1,

      "price":2997,

      "facilities":{

         "totalSize":{

            "value":80

         }

      }

   },

   {

      "publishdate":"2022-04-02 04:03:25",

      "countryid":1,

      "price":250,

      "facilities":{

         "totalSize":{

            "value":30

         }

      }

   }

]

]]>.Value

}

        Return array

    End Function

End Class

​

    Public Module Module1   

        Public Sub Main()

            Console.WriteLine("Environment version: " & Environment.Version.ToString())

            Console.WriteLine("Json.NET version: " & GetType(JsonSerializer).Assembly.FullName)

            Console.WriteLine("")

​

            Try

​

                TestClass.Test()

​

            Catch ex as Exception

​

                Console.WriteLine("Unhandled exception: ")

                Console.WriteLine(ex)

                Throw

​

            End Try

        End Sub 

    End Module

​