Convert Json to Datatable when json has multiple levels - json

Question

In my program, it's the first time that I'm trying to parse JSON content.
The result I'm trying to get is a DataTable with columns like this:
| Text of group | Text of Item | Command of Item |
The JSON is the following:
{
"Groups": [
{
"Items": [
{
"Command": "Framework.Windows.Components.ESScrollerForm, ESGrid|SHOW|Χρήστες|ESGOUser|ESGOUser_def|||65535",
"Key": "834888dd-c4d5-449a-96b7-67db5c3d2692",
"Text": "Users",
"ImageIndex": -1
},
{
"Command": "Framework.Windows.Components.ESScrollerForm, ESGrid|SHOW|QuestionaireSurveyorQuery|ESTMTask|QuestionaireSurveyorQuery|||0",
"Key": "b71de66d-2baf-4452-ada7-8fc67044876b",
"Text": "QuestionaireSurveyorQuery"
}
],
"Expanded": true,
"Tag": "",
"Key": "b741e67a-a3cd-4b97-91cf-ae9c9d9db7d7",
"Text": "Settings",
"ImageIndex": -1
},
{
"Items": [
{
"64String": "Soap",
"Command": "cInvoke|Booked Requests Agent Booking|SHOW|ESMIS|BookedReqAgentBook||False",
"Key": "bfbc3d4a-ef8a-49a0-918a-331813ba90fb",
"Text": "Requests Agent Booking",
"ImageIndex": -1
},
{
"64String": "Jrse",
"Command": "cInvoke|HHG SF Profit \u0026 Loss|SHOW|ESMIS|HHGFileProfitability||False",
"Key": "cf1cbffc-aba9-4e0f-8d6c-ba7219932fb6",
"Text": "HHG SF Profit \u0026\u0026 Loss",
"ImageIndex": -1
}
],
"Tag": "..CSShortcuts\\HHGReporting.ebl",
"Key": "eff0d713-a70e-4582-a103-b8cc5cecdad6",
"Text": "HHGReporting",
"ImageIndex": -1
}
]
}
In the past, I have succesfully parsed complex XML using XPATH, but now I have struggled a lot using Newtonsoft.Json with no success.
What I have tried, is to first create 3 classes using online generators:
Public Class Rootobject
Public Property Groups() As Group
End Class
Public Class Group
Public Property Items() As Item
Public Property Expanded As Boolean
Public Property Tag As String
Public Property Key As String
Public Property Text As String
Public Property ImageIndex As Integer
End Class
Public Class Item
Public Property Command As String
Public Property Key As String
Public Property Text As String
Public Property ImageIndex As Integer
Public Property 64String As String
End Class
Any ideas how the deserialized commands should be, in order the get the data as a DataTable with the structure described?

Answer 1

You have an almost working class model, some changes are necessary to make it work as intended.
This kind of syntax is misleading:
Public Property Groups() As Group
This is not a collection of objects, it's just a single object of Type Group.
Change all to:
Public Property Groups As Group()
'or
Public Property Groups As List(Of Group)
To convert to DataTable with a specific selection of Columns, you need to iterate the Groups collection and, for each group, iterate the Items collection, to extract the values you need.
Here, I'm using a specialized class, GroupsHandler, that contains the class Model used to deserialize a compatible JSON and to convert to DataTable partial content of the resulting data structure.
The GroupsHandler class exposes two Public methods:
Deserialize(), used to convert to .Net classes the JSON content
ToDataTable(), used to create a DataTable from the deserialized content.
You can initialize the handler and call these method as:
Dim handler = New GroupsHandler(Json)
' Only deserialize
Dim myGroups = handler.Deserialize()
' Deserialize and convert to DataTable
Dim dt = handler.ToDataTable()
The Group class name is changed in ItemsGroup, since Group is a language keyword.
The 64String property name changed in String64, since you cannot have a Property Name that begins with a number.
Imports Newtonsoft.Json
Public Class GroupsHandler
Private root As GroupsRoot = Nothing
Private m_json As String = String.Empty
Public Sub New(json As String)
m_json = json
End Sub
Public Function Deserialize() As List(Of ItemsGroup)
root = JsonConvert.DeserializeObject(Of GroupsRoot)(m_json)
Return root.Groups
End Function
Public Function ToDataTable() As DataTable
If root Is Nothing Then
If String.IsNullOrEmpty(m_json) Then Return Nothing
Deserialize()
End If
Dim dt As New DataTable("Groups")
dt.Columns.AddRange(New DataColumn() {
New DataColumn("GroupText", GetType(String)),
New DataColumn("ItemText", GetType(String)),
New DataColumn("ItemCommand", GetType(String))
})
For Each grp In root.Groups
For Each item In grp.Items
dt.Rows.Add(New Object() {grp.Text, item.Text, item.Command})
Next
Next
Return dt
End Function
Public Class GroupsRoot
Public Property Groups As List(Of ItemsGroup)
End Class
Public Class ItemsGroup
Public Property Items As List(Of Item)
<JsonProperty("Expanded", NullValueHandling:=NullValueHandling.Ignore)>
Public Property Expanded As Boolean?
Public Property Tag As String
Public Property Key As Guid
Public Property Text As String
Public Property ImageIndex As Long
End Class
Public Class Item
Public Property Command As String
Public Property Key As Guid
Public Property Text As String
<JsonProperty("ImageIndex", NullValueHandling:=NullValueHandling.Ignore)>
Public Property ImageIndex As Long?
<JsonProperty("64String", NullValueHandling:=NullValueHandling.Ignore)>
Public Property String64 As String
End Class
End Class