Deserialize using JSON.net

Question

I am very new to json, JSON.net and all that. After reading similiar questions here I cannot get my code working. What exactly is my error? What have I overseen? Is it possible to skip the classes "links" and "meta" for testing purposes or do I have to define EVERY property?

I have got the following REST output:

{
   "codes" : [
      {
         "href" : "https://www.someserver.com/form_definitions/OIlG4GxMyeh0sdrt3AYuaXbauGicW71M/field_definitions/zFEova6LiPM/codes/4Sxnr961xzM",
         "rel" : "document_field_definition_code",
         "title" : "TITLE 1"
      },
      {
         "href" : "https://www.someserver.com/form_definitions/OIlG4GxMyeh0sdrt3AYuaXbauGicW71M/field_definitions/zFEova6LiPM/codes/buho0CsLc5k",
         "rel" : "document_field_definition_code",
         "title" : "TITLE 2"
      },
      {
         "href" : "https://www.someserver.com/form_definitions/OIlG4GxMyeh0sdrt3AYuaXbauGicW71M/field_definitions/zFEova6LiPM/codes/RvQoykUM_Sk",
         "rel" : "document_field_definition_code",
         "title" : "TITLE 3"
      }
   ],
   "links" : [
      {
         "about" : "https://www.someserver.com/form_definitions/OIlG4GxMyeh0sdrt3AYuaXbauGicW71M/field_definitions/zFEova6LiPM/codes?about=1",
         "href" : "https://www.someserver.com/form_definitions/OIlG4GxMyeh0sdrt3AYuaXbauGicW71M/field_definitions/zFEova6LiPM/codes",
         "method" : "GET",
         "rel" : "self",
         "title" : null,
         "type" : "codes"
      },
      {
         "href" : "https://www.someserver.com/form_definitions/OIlG4GxMyeh0sdrt3AYuaXbauGicW71M/field_definitions/zFEova6LiPM/codes",
         "method" : "POST",
         "rel" : "codes",
         "title" : "create new codes entity"
      }
   ],
   "meta" : {
      "description" : null,
      "last_page" : 1,
      "page_offset" : 0,
      "page_size" : 50,
      "query-template" : "/codes{?query_search,page_offset,page_size,query_identification,embedded,properties,about}",
      "total" : 6
   }
}

As I unterstood I need three classes: e.g. codes, links and meta.

I created a class "clscodes":

Public Class clsCode
    Private m_href As String
    Private m_rel As String
    Private m_title As String

    Public Property Href As String
        Get
            Return m_href
        End Get
        Set(value As String)
            m_href = value
        End Set
    End Property

    Public Property Rel As String
        Get
            Return m_rel
        End Get
        Set(value As String)
            m_rel = value
        End Set
    End Property

    Public Property Title As String
        Get
            Return m_title
        End Get
        Set(value As String)
            m_title = value
        End Set
    End Property
End Class

And I created a class clsValuelist:

Public Class clsWerteliste

    Private m_code As IList(Of clsCode)

    Public Property Code() As clsCode()
        Get
            Return m_code
        End Get
        Set(value As clsCode())
            m_code = value
        End Set
    End Property
End Class

When I try to deserialize it I get "nothing" as in "CoolOutput"

Dim CoolOutput As New clsWerteliste
CoolOutput = JsonConvert.DeserializeObject(Of clsWerteliste)(jsonstring)

Answer 1

Your classes are pretty close, it looks like you possibly tried to pretty things up a bit such as changing codes to Codes but in so doing the properties no longer match. You can change class names but not property names (at least not that way):

Public Class CodeLinkContainer
    <JsonProperty("codes")>
    Public Property Codes As IList(Of Code)
    <JsonProperty("links")>
    Public Property Links As IList(Of Link)
    <JsonProperty("meta")>
    Public Property Meta As Meta
End Class

Public Class Meta
    Public Property description As Object
    Public Property last_page As Integer
    Public Property page_offset As Integer
    Public Property page_size As Integer
    Public Property querytemplate As String
    Public Property total As Integer
End Class

Public Class Code
    Public Property href As String
    Public Property rel As String
    Public Property title As String
End Class

Public Class Link
    Public Property about As String
    Public Property href As String
    Public Property method As String
    Public Property rel As String
    Public Property title As String
    Public Property type As String
End Class

Using AutoImplement properties, available for some time now, means you can skip all the Get, Set boilerplate code. VS will create the classes for you also:
Edit Menu -> Paste Special -> Paste Json As Classes

You sometimes have to tweak the class if there is an array/list property. For instance, the robots may write:

Public Property elements() As Element

When it should be:

Public Property elements As Element()

The container class shows how to use <JsonProperty("pname")> to change the property name if you wish. This often needs to be done to create an alias for a property name which is a key word in VB (Return, Error etc). In this case, I changed codes and links to be Lists as you did.

    Dim jstr = ... from whereever

    Dim CodeLinks = JsonConvert.DeserializeObject(Of CodeLinkContainer)(jstr)

    Console.WriteLine(CodeLinks.meta.total)
    For Each Item In CodeLinks.codes
        Console.WriteLine(Item.title)
    Next

Result:

6
TITLE 1
TITLE 2
TITLE 3