JSON Encode and Decode with objects in Visual Basic 2010

Question

I have the following code:

Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
Module Module1

Structure JSONList
    Dim Name, Email As String
    Dim Age As Integer
End Structure

Sub Main()
    Dim Data(1) As JSONList

    Data(0).Name = "Josh"
    Data(0).Age = 17
    Data(0).Email = "[email protected]"
    Data(1).Name = "Greg"
    Data(1).Age = 17
    Data(1).Email = "[email protected]"

    Dim JSONEncode As String
    JSONEncode = JsonConvert.SerializeObject(Data)
    Console.WriteLine(JSONEncode)
    Console.WriteLine()
    Console.WriteLine()

    Dim JSONDecode() As JSONList = JsonConvert.DeserializeObject(JSONEncode)
    Console.WriteLine(JSONDecode(0).Name)

    Console.ReadKey()


End Sub

End Module

The first encoding part of the script is used to store the encoded string to a database, the output is:

[{"Name":"Josh","Email":"[email protected]","Age":17},{"Name":"Greg","Email":"[email protected]","Age":17}]

Now when I try to decode this JSON string, I get an error Unable to cast object of type 'Newtonsoft.Json.Linq.JArray' to type 'JSONList[]'.

I need the data to be encoded in the JSON format so that I can use it in my website that uses PHP to decode it. I am using Visual Basic 2010 along with JSON.NET.

Adrian Wragg · Accepted Answer · 2013-09-23 22:51:56Z

1

The problem is that JsonConvert.DeserializeObject deserialises into an object of type Newtonsoft.Json.Linq.JArray which .net cannot automatically convert to an array of JSONList. A little bit of conversion is required:

Dim jsonObject As Newtonsoft.Json.Linq.JArray =
                                        JsonConvert.DeserializeObject(JSONEncode)

Dim JSONDecode() As JSONList = (
                                 From j In jsonObject
                                 Select New JSONList() With {.Age = j("Age"),
                                                             .Email = j("Email"),
                                                             .Name = j("Name")}
                               ).ToArray()

answered Sep 23, 2013 at 22:51

Adrian Wragg

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Comments

Brian Rogers · Accepted Answer · 2013-12-29 01:11:44Z

0

As @Adrian said, JsonConvert.DeserializeObject will deserialize to JArray, which .Net cannot automatically convert into an array of your JSONList structure. However, you don't need to do manual conversion; you simply need to use the overload of DeserializeObject which accepts a type parameter. This will allow Json.Net to deserialize directly to your type without needing any special conversion code.

Dim JSONDecode() As JSONList = _
                 JsonConvert.DeserializeObject(Of JSONList())(JSONEncode)

answered Dec 29, 2013 at 1:11

Brian Rogers

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