How does System.Runtime.Serialization update read-only properties?

[Merrion]

If I have a class with read-only properties that I only want to be created at constructor time e.g.:-

Imports System.Runtime.Serialization
 
''' <summary>
''' An event to indicate that an FX rate was priced between two currencies
''' </summary>
<DataContract()>
Public Class FXRatePricedEvent
    Inherits AggregateIdentity.CurrencyExchangeAggregateIdentity
    Implements IEvent(Of IAggregateIdentity)
 
    <DataMember(Name:="Rate")>
    ReadOnly m_rate As Decimal
    <DataMember(Name:="PriceDate")>
    ReadOnly m_pricedate As Date
    <DataMember(Name:="IsDerived")>
    ReadOnly m_derived As Boolean
 
 
    ''' <summary>
    ''' The conversion rate between source and target currencies
    ''' </summary>
    ReadOnly Property Rate As Decimal
        Get
            Return m_rate
        End Get
    End Property
 
    ''' <summary>
    ''' The date/time the FX rate was priced
    ''' </summary>
    ReadOnly Property PriceDate As Date
        Get
            Return m_pricedate
        End Get
    End Property
 
    ''' <summary>
    ''' Is this rate derived from triangulation or reversal of a priced rate
    ''' </summary>
    ''' <remarks>
    ''' For example a derived GBPJPY can exist s if a priced GBPUSD and USDJPY exist
    ''' </remarks>
    ReadOnly Property IsDerived As Boolean
        Get
            Return m_derived
        End Get
    End Property
 
    Public Sub New(ByVal currencyFrom As AggregateIdentity.CurrencyAggregateIdentity.ISO_3Digit_Currency,
                   ByVal currencyTo As AggregateIdentity.CurrencyAggregateIdentity.ISO_3Digit_Currency,
                   ByVal fxRate As Decimal,
                   ByVal rateDate As Date,
                   ByVal derived As Boolean)
        ' Set the FX rate aggregate identifier
        MyBase.New(currencyFrom, currencyTo)
        ' and set the other properties
        m_rate = fxRate
        m_pricedate = rateDate
        m_derived = derived
    End Sub
 
End Class

Then System.Runtime.Serialization can serialise this to/from XML with no problem. However I want to do something similar but to a key-value pair dictionary....my attempts so to do hit a brick wall unless the class has a constructor with no parameters.

Any ideas how I (or they) get around this?

[Niya]

However I want to do something similar but to a key-value pair dictionary.

Can you give some details on what you mean by this ? I ask because people generally don't care how an object is serialized, only that we can serialize and deserialize it correctly.

[dday9]

You could try this and see if it works for you:

Option Strict On
Option Explicit On

Imports System.ComponentModel
Public Class Class1

    Private dic As Dictionary(Of String, String)
    <Xml.Serialization.XmlIgnore()> _
    Public Property Dictionary() As Dictionary(Of String, String)
        Get
            Return dic
        End Get
        Set(ByVal value As Dictionary(Of String, String))
            dic = value
        End Set
    End Property

    Private key() As String
    <Browsable(False)> _
    Public Property Keys() As String()
        Get
            Return key
        End Get
        Set(ByVal value() As String)
            key = value
        End Set
    End Property

    Private mValue() As String
    <Browsable(False)> _
    Public Property Values() As String()
        Get
            Return mValue
        End Get
        Set(ByVal value() As String)
            mValue = value
        End Set
    End Property

    Public Event dictionaryChanged As Action

    Private Sub Class1_dictionaryChanged() Handles Me.dictionaryChanged
        ReDim key(dic.Count - 1)
        ReDim mValue(dic.Count - 1)

        For i As Integer = 0 To dic.Count - 1
            key(i) = dic.Keys(i)
            mValue(i) = dic.Values(i)
        Next
    End Sub

    Sub New()

        For i As Integer = 0 To mValue.Length
            dic.Add(key(i), mValue(i))
        Next

    End Sub

End Class