How to read JSON http post response using VB - vb.net

Question

I have the following code, it connects to PHP server and retrieve data successfully, i'm not very good with VB, how can i read the JSON response text and extract it's elements?
Public Class Form1
Private Sub submit_Click(sender As System.Object, e As System.EventArgs) Handles submit.Click
Dim user As String
Dim pass As String
user = uname.Text
pass = passwd.Text
Dim request As WebRequest = WebRequest.Create("http://domain.com/test.php")
request.Method = "POST"
Dim postData As String
postData = "username=" & user & "&password=" & pass
Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postData)
request.ContentType = "application/x-www-form-urlencoded"
request.ContentLength = byteArray.Length
Dim dataStream As Stream = request.GetRequestStream()
dataStream.Write(byteArray, 0, byteArray.Length)
dataStream.Close()
Dim response As WebResponse = request.GetResponse()
Console.WriteLine(CType(response, HttpWebResponse).StatusDescription)
dataStream = response.GetResponseStream()
Dim reader As New StreamReader(dataStream)
Dim responseFromServer As String = reader.ReadToEnd()
If responseFromServer = "0" Then
MsgBox("Login Failed")
Else
MsgBox("json data")
End If
reader.Close()
dataStream.Close()
response.Close()
End Sub
End Class
The JSON response would be something like:
{"comments": [
{
"comment" : "some text",
"date" : "some date",
"user" : "user name"
},
{
"comment" : "some text",
"date" : "some date",
"user" : "user name"
}
],
"messages": [ .... ]
}
How to output the json string into:
Comments
user date comment
-----------------------------------
user 1 date 1 comment 1
user 2 date 2 comment 2
Messages
user date message
-----------------------------------
user 1 date 1 message 1
user 2 date 2 message 2

Answer 1

After long research and many tests I found out a very nice extension called Newtonsoft.json, it's extremely simple and can be installed from package manager console like this:
install-package Newtonsoft.json
And include it like this:
Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
Then all i needed to do is to declare the elements names and values like this:
Else
Dim json As String = responseFromServer
Dim ser As JObject = JObject.Parse(json)
Dim data As List(Of JToken) = ser.Children().ToList
Dim output As String = ""
For Each item As JProperty In data
item.CreateReader()
Select Case item.Name
Case "comments"
output += "Comments:" + vbCrLf
For Each comment As JObject In item.Values
Dim u As String = comment("user")
Dim d As String = comment("date")
Dim c As String = comment("comment")
output += u + vbTab + d + vbTab + c + vbCrLf
Next
Case "messages"
output += "Messages:" + vbCrLf
For Each msg As JObject In item.Values
Dim f As String = msg("from")
Dim t As String = msg("to")
Dim d As String = msg("date")
Dim m As String = msg("message")
Dim s As String = msg("status")
output += f + vbTab + t + vbTab + d + vbTab + m + vbTab + s + vbCrLf
Next
End Select
Next
MsgBox(output)
End If
hope someone will find this useful

Answer 2

#razzak is absolutely right to use the Json.Net NuGet package. Another option that would cut this down dramatically, is to use the built in DeserializeObject function. As long as you have a well define model, then you can deserialize the Json right into an instance of the object using something like this:
dim myObject as MyDefinedObject = JsonConvert.DeserializeObject(responseFromServer)
or this in C#
MyDefinedObject m = JsonConvert.DeserializeObject<MyDefinedObject>(responseFromServer);
Also, if you don't want to loop, you could also select tokens using something like this:
Dim d = ser.SelectToken("$..resources[?(#)].travelDistance")
This code above was used to locate the travelDistance between two points from the Bing API. If you have ever dealt with the Bing or Google Map REST APIs, then you know the JSon is generally too large to loop through the data when you are looking for very specific values.
The JSon.Net website has a blog page that goes through some additional examples:
http://james.newtonking.com/json

Answer 3

To use
Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
'Json.Net' library should be installed.

Answer 4

Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
This seems to cut it on VB.net for youtube API V.3
of course it depends on what you are trying to accomplish
but Youtube returns data as Json format