Imports System

Imports System.Linq

Imports System.Collections

Imports System.Collections.Generic

Imports System.Data

Imports System.IO

Imports System.Globalization

Imports System.Reflection

Imports System.ComponentModel.DataAnnotations

Imports System.Xml.Linq

Imports System.Xml

Imports Microsoft.VisualBasic

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 DeserializeObjects(Of T)(ByVal stream As Stream, 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 DeserializeObjects(Of T)(textReader, settings)

                Yield item

            Next

        End Using

    End Function

​

    ' Adapted from this answer https://stackoverflow.com/a/43747641/3744182

    ' By https://stackoverflow.com/users/7912895/nocodename

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

    Iterator Function DeserializeObjects(Of T)(ByVal textReader As TextReader, 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.StartObject Then

                    Yield serializer.Deserialize(Of T)(reader)

                End If

            End While

        End Using

    End Function

​

    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

​

Public Module TestClass 

    Friend Sub Test()

        Test1(GetJson())

​

        Console.WriteLine()

        Test2(GetJson())

​

        Console.WriteLine()

        Test3(JArray.Parse(GetJson())(0), 30000)

    End Sub

​

    Friend Sub Test1(ByVal json As String)

        Dim FileName = "Question74027865.json"

        File.WriteAllText(FileName, json)

​

        Using stream = File.OpenRead(FileName)

            Dim regex as Regex = new Regex("^\[[0-9]+\]\.facilities\.totalSize\.value$", RegexOptions.CultureInvariant Or RegexOptions.Compiled Or RegexOptions.Singleline)

            Console.WriteLine(regex)

            For Each value As Decimal in JsonExtensions.DeserializeItemsByPath(Of Decimal)(stream, regex)

                Console.WriteLine("totalSize: {0}", value)

            Next

        End Using

​

        File.Delete(FileName)

    End Sub 

​

    Friend Sub Test2(ByVal json As String)

        Dim FileName = "Question74027865.json"

        File.WriteAllText(FileName, json)

​

        Using stream = File.OpenRead(FileName)

            For Each jt As JObject in JsonExtensions.DeserializeObjects(Of JObject)(stream)

                Dim valueToken as JToken = jt.SelectToken("facilities.totalSize.value")

                If (valueToken IsNot Nothing)

                    Console.WriteLine("totalSize: {0}", valueToken)

                End If

            Next

        End Using

​

        File.Delete(FileName)

    End Sub 

​

    Friend Sub Test3(Of T)(ByVal jObj as T, inCount as Integer)

        Dim FileName = "Question74027865.json"

        Using stream = File.OpenWrite(FileName)

            Using textWriter = new StreamWriter(stream)

                Using jsonWriter = new JsonTextWriter(textWriter)

                    JsonSerializer.CreateDefault().Serialize(textWriter, Enumerable.Range(0, inCount).Select(Function(i) jObj))

                End Using

            End Using

        End Using

​

        Dim total as Decimal = 0D

        Dim count as Integer = 0

​

        Using stream = File.OpenRead(FileName)

            Dim regex as Regex = new Regex("^\[[0-9]+\]\.facilities\.totalSize\.value$", RegexOptions.CultureInvariant Or RegexOptions.Compiled Or RegexOptions.Singleline)

            Console.WriteLine(regex)

            For Each value As Decimal in JsonExtensions.DeserializeItemsByPath(Of Decimal)(stream, regex)

                total += value

                count += 1

            Next

        End Using

​

        Console.WriteLine("Grand total of {0} items: {1}.", count, total)

        File.Delete(FileName)

    End Sub 

​

​

    Function GetJson() as String

        Dim Jstring As String = <![CDATA[

[

  {

    "countryid": 1,

    "price": 2997,

    "facilities": {

      "totalSize": {

        "value": 80

      }

    }

  },

  {

    "countryid": 1,

    "price": 12997,

    "facilities": {

      "totalSize": {

        "value": 180

      }

    }

  },

  {

    "countryid": 1,

    "price": 10,

    "facilities": {

      "totalSize": {

      }

    }

  },

]

]]>.Value       

        Return Jstring      

    End Function

End Module

​

    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

​

#If False Then

    <System.Runtime.CompilerServices.Extension()>

    Public Function ReadToContentAndAssert(ByVal reader As JsonReader) As JsonReader

        Return JsonExtensions.ReadAndAssert(reader).MoveToContentAndAssert()

    End Function

​

    <System.Runtime.CompilerServices.Extension()>

    Public Function MoveToContentAndAssert(ByVal reader As JsonReader) As JsonReader

        If reader Is Nothing Then Throw New ArgumentNullException()

        If reader.TokenType = JsonToken.None Then reader.ReadAndAssert()       ' Skip past beginning of stream.

​

        While reader.TokenType = JsonToken.Comment ' Skip past comments.

            reader.ReadAndAssert()

        End While

​

        Return reader

    End Function

​

    <System.Runtime.CompilerServices.Extension()>

    Public Function ReadAndAssert(ByVal reader As JsonReader) As JsonReader

        If reader Is Nothing Then Throw New ArgumentNullException()

        If Not reader.Read() Then Throw New JsonReaderException("Unexpected end of JSON stream.")

        Return reader

    End Function

#End If

​