I'm trying to implement the table per class hierarchy model for
itineraries in my app. I have a single Itinerary table, and the
Movement field will have either an "I" or "O" as the discriminator for
"inbound" or "outbound" itineraries.
I have set up an "IItinerary" interface to use as my parent class.
Both InboundItinerary and OutboundItinerary classes implement this.
They also inherit from a base Itinerary class, that in turn inherits
from a BaseObject class that I use for most of the objects in my app.
The problem I'm having is that it doesn't seem to be able to determine
what type of itinerary each record is when they get loaded. I get
this error:
"Object with id: 1 was not of the specified subclass:
MyApp.DomainEntities.InboundItinerary (loading object was of wrong
class [MyApp.DomainEntities.OutboundItinerary])"
Am I doing something wrong in my implementation? I found some similar
issues while searching for an answer, and I turned off lazy loading
because that seemed to fix it for some people. Is there something
else I'm missing?
Itinerary Table
------------------------------------------------------
CREATE TABLE [dbo].[Itinerary](
[Id] [int] IDENTITY(1,1) NOT NULL,
[EnrollmentId] [int] NOT NULL,
[PersonnelId] [int] NULL,
[AirlineId] [smallint] NOT NULL,
[Movement] [char](1) NULL,
[FlightNumber] [varchar](25) NOT NULL,
[DepartureLocation] [varchar](25) NOT NULL,
[DepartureTime] [smalldatetime] NOT NULL,
[ArrivalLocation] [varchar](25) NOT NULL,
[ArrivalTime] [smalldatetime] NOT NULL,
[SpecialInstructions] [varchar](max) NULL CONSTRAINT
[DF_Itinerary_Instructions] DEFAULT (space((0))),
[ModifiedDate] [smalldatetime] NULL CONSTRAINT [DF_Itinerary_Date]
DEFAULT (getdate()),
CONSTRAINT [PK_Itinerary] PRIMARY KEY CLUSTERED
(
[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY
= OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
------------------------------------------------------
Itinerary Mapping
------------------------------------------------------
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyApp.DomainEntities, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=01ca2278eac9ed50" namespace="MyApp.DomainEntities"
default-lazy="false">
<class name="IItinerary" table="Itinerary" abstract="true"
discriminator-value="A">
<id name="Id" column="Id" type="Int32">
<generator class="native" />
</id>
<discriminator column="Movement" type="Char" />
<subclass name="InboundItinerary" discriminator-value="I"
lazy="false">
<many-to-one name="Personnel" column="PersonnelId"
class="Personnel"/>
<many-to-one name="ClassEnrollment" column="EnrollmentId"
class="ClassEnrollment"/>
<many-to-one name="Airline" column="AirlineId" class="Airline"/>
<property name="FlightNumber" type="String" />
<property name="DepartureLocation" type="String" />
<property name="DepartureTime" type="DateTime" />
<property name="ArrivalLocation" type="String" />
<property name="ArrivalTime" type="DateTime" />
<property name="Instructions" column="SpecialInstructions"
type="String" />
<property name="ModifiedDate" type="DateTime" />
</subclass>
<subclass name="OutboundItinerary" discriminator-value="O"
lazy="false">
<many-to-one name="Personnel" column="PersonnelId"
class="Personnel"/>
<many-to-one name="ClassEnrollment" column="EnrollmentId"
class="ClassEnrollment"/>
<many-to-one name="Airline" column="AirlineId" class="Airline"/>
<property name="FlightNumber" type="String" />
<property name="DepartureLocation" type="String" />
<property name="DepartureTime" type="DateTime" />
<property name="ArrivalLocation" type="String" />
<property name="ArrivalTime" type="DateTime" />
<property name="Instructions" column="SpecialInstructions"
type="String" />
<property name="ModifiedDate" type="DateTime" />
</subclass>
</class>
</hibernate-mapping>
------------------------------------------------------
IItinerary Interface
------------------------------------------------------
Public Interface IItinerary
Property Airline() As Airline
Property ArrivalLocation() As String
Property ArrivalTime() As Nullable(Of DateTime)
Property ClassEnrollment() As ClassEnrollment
Property Personnel As Personnel
ReadOnly Property Movement As Char
Property ModifiedDate() As Nullable(Of DateTime)
Property DepartureLocation() As String
Property DepartureTime() As Nullable(Of DateTime)
Property FlightNumber() As String
Property Id() As Integer
Property Instructions() As String
End Interface
------------------------------------------------------
Itinerary Base Class
------------------------------------------------------
<Serializable()> _
Public MustInherit Class Itinerary
Inherits BaseObject
Implements IComparable
Public MustOverride Function CompareTo(ByVal obj As Object) As
Integer Implements System.IComparable.CompareTo
End Class
------------------------------------------------------
InboundItinerary Class (Outbound is essentially identical aside from
the name)
------------------------------------------------------
<Serializable()> _
Public Class InboundItinerary
Inherits Itinerary
Implements IComparable
Implements IItinerary
Private _airline As Airline
Private _arrivalLocation As String
Private _arrivalTime As Nullable(Of DateTime)
Private _departureLocation As String
Private _departureTime As Nullable(Of DateTime)
Private _enrollment As ClassEnrollment
Private _flightNumber As String
Private _id As Integer
Private _instructions As String
Private _movement As Char
Private _modifiedDate As Nullable(Of DateTime)
Private _personnel As Personnel
Public Overridable Property Airline() As Airline Implements
IItinerary.Airline
Get
Return _airline
End Get
Set(ByVal value As Airline)
_airline = value
End Set
End Property
Public Overridable Property ArrivalLocation() As String Implements
IItinerary.ArrivalLocation
Get
Return _arrivalLocation
End Get
Set(ByVal value As String)
_arrivalLocation = value
End Set
End Property
Public Overridable Property ArrivalTime() As Nullable(Of DateTime)
Implements IItinerary.ArrivalTime
Get
Return _arrivalTime
End Get
Set(ByVal value As Nullable(Of DateTime))
_arrivalTime = value
End Set
End Property
Public Overridable Property ClassEnrollment() As ClassEnrollment
Implements IItinerary.ClassEnrollment
Get
Return _enrollment
End Get
Set(ByVal value As ClassEnrollment)
_enrollment = value
End Set
End Property
Public Overridable Property DepartureLocation() As String
Implements IItinerary.DepartureLocation
Get
Return _departureLocation
End Get
Set(ByVal value As String)
_departureLocation = value
End Set
End Property
Public Overridable Property DepartureTime() As Nullable(Of
DateTime) Implements IItinerary.DepartureTime
Get
Return _departureTime
End Get
Set(ByVal value As Nullable(Of DateTime))
_departureTime = value
End Set
End Property
Public Overridable Property FlightNumber() As String Implements
IItinerary.FlightNumber
Get
Return _flightNumber
End Get
Set(ByVal value As String)
_flightNumber = value
End Set
End Property
Public Overridable Property Id() As Integer Implements
IItinerary.Id
Get
Return _id
End Get
Set(ByVal value As Integer)
_id = value
End Set
End Property
Public Overridable Property Instructions() As String Implements
IItinerary.Instructions
Get
Return _instructions
End Get
Set(ByVal value As String)
_instructions = value
End Set
End Property
Public Overridable ReadOnly Property Movement As Char Implements
IItinerary.Movement
Get
Return "I"
End Get
'Set(value As Boolean)
' value = True
'End Set
End Property
Public Overridable Property ModifiedDate() As Nullable(Of
DateTime) Implements IItinerary.ModifiedDate
Get
Return _modifiedDate
End Get
Set(value As Nullable(Of DateTime))
_modifiedDate = value
End Set
End Property
Public Overridable Property Personnel As Personnel Implements
IItinerary.Personnel
Get
Return _personnel
End Get
Set(ByVal value As Personnel)
_personnel = value
End Set
End Property
Public Overrides Function CompareTo(ByVal obj As Object) As
Integer
Dim objArrivalDate As DateTime = Nothing
If TypeOf (obj) Is InboundItinerary Then
With CType(obj, InboundItinerary)
objArrivalDate = .ArrivalTime.GetValueOrDefault
End With
End If
Return Date.Compare(Me.ArrivalTime.GetValueOrDefault,
objArrivalDate)
End Function
End Class
------------------------------------------------------
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