I am currently writing an API which is taking objects from a web service handling it in VB.net using the Newsoft JSON .NET library.
I'm deserializing a JSON array called Vehicles into a list of vehicles.
Here is the important code snippets:
Public Class VehicleList
Public Vehicles() As Vehicle
End Class
Public Class Vehicle
Public Property licence_plate_number As String
End Class
Here we have a web client that grabs the json and put it into the objects.
Public Class dcVehicles
Private Property _Vehicles As VehicleList
Public ReadOnly Property Vehicle As Vehicle()
Get
Return _Vehicles.Vehicles
End Get
End Property
Public Sub Refresh()
_Vehicles = JsonConvert.DeserializeObject(Of VehicleList)(wcReply, jsSettings)
End Sub
End Class
There's slightly more to it (cut it down). So everything is working as intended, json net is creating an array of vehicles.
I'm trying to achieve this with the properties in the vehicle class as private and read only, the applications using the api should not be able to set these.
The problem is I've tried changing the public property in the vehicle class to keep the property private and allow readonly as below:
Public Class Vehicle
Friend Property licence_plate_number As String
Public ReadOnly Property RegistrationNumber As String
Get
Return licence_plate_number
End Get
End Property
End Class
The problem I then get is that JSON.net is unable to populate the vehicles. All 3 classes are in the same namespace. So I tried licence_plate_number with the Friend/private access level modifier but still Json net is unable to populate the object.
The only way is keeping it as Public.
Does anyone have an idea for a work-around? Or is am I missing something simple?
Thanks
If you just want to serialize a Private
or Friend
property with Json.NET, mark it with <JsonProperty>
and mark the public readonly property you don't want to serialize with <JsonIgnore>
:
Public Class Vehicle
<JsonProperty> _
Friend Property licence_plate_number As String
<JsonIgnore> _
Public ReadOnly Property RegistrationNumber As String
Get
Return licence_plate_number
End Get
End Property
End Class
Demo fiddle.
But if you really want read-only value semantics for the licence_plate_number
property so that it cannot be set after construction, you can do this by replacing the default constructor with a single parameterized constructor and matching the constructor argument names to the JSON property names, like so:
Public Class Vehicle
Private Readonly licence_plate_number As String
Public Sub New(ByVal licence_plate_number as String)
Me.licence_plate_number = licence_plate_number
End Sub
<JsonProperty("licence_plate_number")> _
Public ReadOnly Property RegistrationNumber As String
Get
Return licence_plate_number
End Get
End Property
End Class
When there is a single public constructor that is parameterized, Json.NET will call it, matching the constructor arguments to the JSON properties by name using reflection and using default values for missing properties. Matching by name is case-insensitive, unless there are multiple matches that differ only in case, in which case the match becomes case sensitive.
Demo fiddle.
If your class has multiple public constructors, mark the one to use with <JsonConstructor>
.