VB.NET syntax for Newtonsoft JsonProperty order property

Question

I am trying to set the order in which various JSON properties get serialised, and all the examples I can find are using C#, and are like:

[JsonProperty(Order = 1)]

but I cannot find a way to write this in VB.NET which Visual Studio will accept - the obvious:

<JsonProperty(Order = 1)>  

gives errors and won't compile .... (no doubt there's a way to format that last line, but...)

As I also need to set the property name for the same property, e.g.

[JsonProperty(PropertyName = "CardCode")]

in c#, how can I set both the name and order in vb.net using JsonPropertyAttribute?

Answer 1

The syntax for applying attributes with parameters in vb.net is described in Attributes overview (Visual Basic): Attribute Parameters:

Attribute Parameters

Many attributes have parameters, which can be positional, unnamed, or named. Any positional parameters must be specified in a certain order and cannot be omitted; named parameters are optional and can be specified in any order. Positional parameters are specified first. For example, these three attributes are equivalent:

<DllImport("user32.dll")>  
<DllImport("user32.dll", SetLastError:=False, ExactSpelling:=False)>  
<DllImport("user32.dll", ExactSpelling:=False, SetLastError:=False)>

Thus, if you want to apply JsonPropertyAttribute to a property and set both the name and order, you must do:

Public Class Card
    <JsonProperty(PropertyName:="CardName", Order:=2)>
    Public Property Name As String

    <JsonProperty(PropertyName:="CardDescription", Order:=3, _
            NullValueHandling := NullValueHandling.Ignore, DefaultValueHandling := DefaultValueHandling.IgnoreAndPopulate)>
    <System.ComponentModel.DefaultValue("")>
    Public Property Description As String

    <JsonProperty(PropertyName:="CardCode", Order:=1)>
    Public Property Code As String
End Class

Notes:

• As shown by the setting AllowMultiple = false in the source code, only one instance of JsonPropertyAttribute can be applied to a given member or parameter:

  [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property | AttributeTargets.Parameter, AllowMultiple = false)]
  public sealed class JsonPropertyAttribute : Attribute
  {
       // Contents of the type omitted
  }
  

  Thus all necessary JsonPropertyAttribute settings must be initialized in that one attribute.

• The line continuation character _ can be used to break attribute settings across multiple lines. Attributes can be applied on the line(s) immediately preceding a property, however, so it is not necessary to use it in this case.

• According to the JSON standard a JSON object is an unordered set of name/value pairs, so it is often not necessary to specify the order.

Sample VB.NET fiddle here.