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

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

vb.net Code:

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?

Quote:

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Originally Posted by Merrion

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

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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.

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

Code:

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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

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