OK, so I have a base class called ThirdParty, and have 2 derived classes from that; Person and Company.
Most of the information I need is stored up in ThirdParty, and the additional not so common bits in Person and Company. The ThirdParty is responsible for saving its data and the dervived objects is responsible for saving its data. So far so good? Right?
Except one small little snag. It doesn't work! (heh)
ThirdParty can't exist on its own, so I've made it abstract:
Public
MustInherit Class ThirdPartyInherits BusinessBase(Of ThirdParty)
The base object simply inherit from this:
Public Class Person
Inherits ThirdParty
Now, the problem is the fact ThirdParty is abstract so CSLA can't create an instance of it. So I get this error.
ThirdPartyTestFixture.ThirdPartyPerson_CreateAndReadBack : Csla.DataPortalException : DataPortal.Fetch failed
----> System.MissingMethodException : Cannot create an abstract class.
I appreciate the error, obviously it can't create an abstract class. *but* has anyone successfully acheived this in another way? All help greatly appreciated :)
Paul
I saw Rockys previous post on this subject, where you pass the type into the base class. However, having done that, I now get:
ThirdPartyTestFixture.ThirdPartyPerson_CreateAndReadBack : Csla.DataPortalException : DataPortal.Fetch failedI'm using CSLA 2.0.1 as suggested.
My abstract class now looks like:
Public MustInherit Class ThirdParty(Of T As ThirdParty(Of T)) Inherits BusinessBase(Of ThirdParty(Of T))
PaulD:
My abstract class now looks like:
Public MustInherit Class ThirdParty(Of T As ThirdParty(Of T))
Inherits BusinessBase(Of ThirdParty(Of T))
Inherits BusinessBase(Of T)
should workStefan
Hi Rocky,
Yeh you hit the nail on the head with that one. I changed my Criteria to be:
#
Region " Criteria class"<Serializable()> _
Public Class ThirdPartyCriteria(Of T As BusinessBase)
Inherits CriteriaBase
#Region " Private declarations"
Private _thirdPartyId As Guid
#End Region
#
Region " Constructors"...
And it works perfectly.
Thanks :)
I am having the same problem. After reading the posts I changed my Base Object to the what is below. Everything now complies, but the DataPortal_Fetch Cannot find the correct method since it is looking for DataPortal_Fetch (object). What am I doing wrong?
My goal for doing this is to allow all my data access to take place in the in Base Class (using Code Gen) and have all the business logic included in the Project Class. I have thought about using partial classes to accomplish this, but I would like to have the ability to override the base class functionality if necessary. Any thoughts and help would be greatly appreciated.
Public MustInherit Class ProjectBase(Of T As ProjectBase(Of T))
Inherits BusinessBase(Of T)
...
Protected Class Criteria(Of ProjectBase) Inherits CriteriaBase...
Private
Overloads Sub DataPortal_Fetch(ByVal criteria As Criteria(Of ProjectBase(Of T)))Check This Post: http://forums.lhotka.net/forums/thread/1052.aspx
The link you provided does not help as the criteria object was created in the sub classes not the base class. My problem is if I create the Criteria Class and Data Portal methods in the Base Class then the call DataPortal.Fetch(Of Project)(New Criteria(Of Project)(Id)) from the sub class, the code never actually calls the DataPortal_Fetch in the Base Class since the signature of the function is not
DataPortal_Fetch(ByVal criteria As Criteria)
But is
DataPortal_Fetch(
ByVal criteria As Criteria(Of ProjectBase(Of T))Am I making any sense?
Any ideas on what I can do?
Thanks.
I never intended for criteria classes to be generic. My guess is that the data portal code that invokes the DataPortal_XYZ methods would need extra code to deal with generic parameters.
Criteria classes are supposed to be simple DTO (data transfer object) style objects that just ferry your criteria data from the client to the server. I haven't had time to read this thread and understand why you'd be making the criteria class generic?
Rocky,
Thanks for taking time to answer the post. What I am trying to do is use code generation to handle all the database access for my business objects. I thought I would create a base class for each business object that would contain all database access code as well as private variables and public members. My actual business objects would inherit from these base classes and implement all the business rules. This way if something changed in the database, I could regenerate the database access code without losing all the business rules. I hope I am making sense.
Do you have any advice on how to go about accomplishing this? Would you use partial classes or not do this at all?
Thanks. Mike
From: mr_lasseter [mailto:cslanet@lhotka.net]
Sent: Thursday, July 06, 2006 9:50 PM
To: rocky@lhotka.net
Subject: Re: [CSLA .NET] Inheriting from a business objectRocky,
Thanks for taking time to answer the post. What I am trying to do is use code generation to handle all the database access for my business objects. I thought I would create a base class for each business object that would contain all database access code as well as private variables and public members. My actual business objects would inherit from these base classes and implement all the business rules. This way if something changed in the database, I could regenerate the database access code without losing all the business rules. I hope I am making sense.
Do you have any advice on how to go about accomplishing this? Would you use partial classes or not do this at all?
Thanks. Mike
Oops - didn't notice that this email WAS from the forum ![Surprise [:O]](/emoticons/emotion-3.gif)
Well then, I suggest that you check out some of the other threads on code-gen in the forum you are already reading ![Wink [;)]](/emoticons/emotion-5.gif)
Nothing you are trying to do is new or unique, and there are examples available (specifically the CodeSmith templates and Kathleen Dollard's code-gen book) that illustrate how to do what you want.
Copyright (c) Marimer LLC