JSON string and DatacontractJsonDeserializer

Question

I am trying to parse a Json String that is returned let is say from a service. For simplicity it will be like:

Dim jsonstring = _
<s>
{"menu": {
"id": "file",
"value": "File",
"popup": {
"menuitem": [
  {"value": "New", "onclick": "CreateNewDoc()"},
  {"value": "Open", "onclick": "OpenDoc()"},
  {"value": "Close", "onclick": "CloseDoc()"}
]
}
}}
</s>.Value

Now I am using the following function to read the json string to an object however all the properties are always nothing. I have created an object for each json object in the above string and the object has Datacontract and Datamember attributes. Any tips please?

Dim menu = JsonObject(Of Menu)(jsonstring)
    Console.WriteLine(menu.value)

Private Function JsonObject(Of t)(jsonString As String) As t
    Dim ser As New DataContractJsonSerializer(GetType(t))
    Dim ms As New MemoryStream(Encoding.UTF8.GetBytes(jsonString))
    ms.Position = 0
    Dim obj As t = DirectCast(ser.ReadObject(ms), t)
    Return obj
End Function

Maggie Ying · Accepted Answer · 2012-11-19 21:14:19Z

1

By looking at this call:

Console.WriteLine(menu.value)

I am suspecting that the Menu class is not defined correctly... Does your Menu class has a property called 'menu' and does the type of this 'menu' property is a complex type with the properties called 'id', 'value', 'popup'?

answered Nov 19, 2012 at 21:14

Maggie Ying

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user1829319 · Accepted Answer · 2012-11-20 01:34:18Z

0

Thanks for the reply.

I used Json2cshap.com to convert this Json String to classes. The classes (c#) version looks like this. The only difference is that mine is VB.net and all classes / properties have and attributes.

public class Menuitem
{
    public string value { get; set; }
    public string onclick { get; set; }
}

public class Popup
{
    public List<Menuitem> menuitem { get; set; }
}

public class Menu
{
    public string id { get; set; }
    public string value { get; set; }
    public Popup popup { get; set; }
}

public class RootObject
{
    public Menu menu { get; set; }
}

Should the root object (RootObject) to be called Menu? I cannot test it right now but give your suggestion a go.

answered Nov 20, 2012 at 1:34

user1829319

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