Inheritance in the Entity Framework

re: Inheritance in the Entity Framework

jvierra — Fri, 16 Mar 2007 02:44:15 GMT

One thing I can see when looking at the blog source is that there is a fair amount of bloat due to teh MSOffice formatting.

I wonder if, under some circumstances, this may cause slow rendering performance?

I mention this because, on many sites, IE7 tends to build it's page very slowly. Not this on for me but it does happen. The same site on IE6 render norrmally.

Is it machine settings or IE7 issues with some layouts?

Inheritance in the Entity Framework

ArchitectualInsight — Fri, 16 Mar 2007 22:31:35 GMT

I was/am so busy in two projects , there was no time for any blah blah and blogging.. I still don't have

re: Inheritance in the Entity Framework

Giancarlo Sudano — Sat, 17 Mar 2007 01:56:41 GMT

how do you manage polimorphic query with inheritance?

In NHibernate if I use a TPC strategy, and I create a query "from BaseClass" I usually obtain a SELECT with UNION from all several table per concrete.

Normally for a polimorphic query a TPH or a Table per Subclass strategy (S.Ambler definition) is better.

Do Entity Framework manages polimorphic query?

Thanks!

re: Inheritance in the Entity Framework

Steve — Sat, 17 Mar 2007 16:29:38 GMT

First things first, how about adding 1:1 support :)

Isn't that missing from this CTP?

By the way, I'd like to have the EF use an NHibernate approach where mapping files are used as above, without cluttering the entity/value objects.

New and Notable 149

Sam Gentile — Sun, 18 Mar 2007 05:03:00 GMT

Yup, I'm still stuck in Seattle and I still feel like crap. Tomas just went off to the airport and I

re: Inheritance in the Entity Framework

Erick Thompson — Sun, 18 Mar 2007 21:24:34 GMT

re: Do Entity Framework manages polimorphic query?

Entity Framework queries can indeed handle polymorphic queries, in that you can query for a base type, derived type, etc.

re: By the way, I'd like to have the EF use an NHibernate approach where mapping files are used as above, without cluttering the entity/value objects.

With the Entity Framework, the mapping files all live on thier own, so there is no merging of mapping, store and objects. In additon, with a forthcoming release of the Entity Framework, we will be supporting the ability to use your own objects (not using our code gen) with the EF.

re: Inheritance in the Entity Framework

Arjen de Blok — Wed, 21 Mar 2007 15:25:08 GMT

I would also like that to use the POCO style from NHibernate with the Entity Framework.

Thus that the entity classes have no dependency on the entity framework. So no specific base classes where you must derive from or .NET attributes.

Implementing interfaces like INotifyPropertyChanged is no problem for me.

re: Inheritance in the Entity Framework

Steve.Walker@gmail.com — Thu, 22 Mar 2007 08:05:43 GMT

How might one implement the entity framework from an ETL standpoint? Is that a valid idea at all? e.g. pre-ado.net data access layer...

re: Inheritance in the Entity Framework

Steve.S.Walker@gmail.com — Thu, 22 Mar 2007 08:05:56 GMT

How might one implement the entity framework from an ETL standpoint? Is that a valid idea at all? e.g. pre-ado.net data access layer...

Resumo da semana - 26/03/07

Console.Write(this.Opinion) — Mon, 26 Mar 2007 18:36:36 GMT

Esta semana não foi tão animada quanto a semana passada.. ASP.Net Sébastien Just fez uma compilação das

re: Inheritance in the Entity Framework

WeLikeIke — Mon, 02 Apr 2007 19:19:04 GMT

I can't seem to get an Association/AssociationSet End Role in a .csdl file to work if the End Role type is derived from the EntitySet type. Is that even a possible scenario?

The other part of that problem is that apparantly in the .msl file, I must include the mappings for all types derived from a base object within the base object's EntitySetMapping node. Otherwise I get an error stating that a particular TableMappingFragment is basically defined twice and could lead to data corruption.

In other words, using the example .csdl at...

http://blogs.msdn.com/adonet/archive/2007/02/12/entity-data-model-101-part-2.aspx

...how would you change the type of the End Role "ManagedEmployee" in Association "FK_Employee_Employee_ManagerID" from "Employee" to "SalesEmployee"?

Thanks...

re: Inheritance in the Entity Framework

WeLikeIke — Mon, 02 Apr 2007 20:47:30 GMT

Uhh..I think I found the answer which stinks if true.

Again, from http://blogs.msdn.com/adonet/archive/2007/02/12/entity-data-model-101-part-2.aspx ...

"Any associations using a derived type must be declared on the base type because the derived type does not declare an entity set in the entity container. The entity set is needed to define the scope of an association using the derived type."

Please say it ain't so. To me, that seems like a severe limitation.

re: Inheritance in the Entity Framework

WeLikeIke — Mon, 02 Apr 2007 21:03:32 GMT

Found more regarding derived type associations (relationships).

I guess that functionality is being considered:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=967167&SiteID=1

Sure would be nice if it gets included...

re: Inheritance in the Entity Framework

Paymon Khamooshi — Sun, 02 Mar 2008 12:33:33 GMT

It will be great to add a standard Parse() method to the database context's table properties to accept the ToString() value of an instance and do the query based on the configurations.

Currently the developer needs to know which field to search for, i.e:

dbContext.Publishers.Single(p => p.Name == "Wrox")

this can be simplified as

dbContext.Publishers.Parse("Wrox")

ADO.NET team blog : Inheritance in the Entity Framework

Dating — Sat, 31 May 2008 21:28:51 GMT

One of the coolest features of the ADO.NET Entity Framework is the ability to use inheritance in your database! Very cool, but what does it mean, and why is it important? War of the worlds Relational The world of relational data is based around tuples

ADO.NET team blog : Inheritance in the Entity Framework

Weddings — Thu, 05 Jun 2008 13:20:09 GMT

re: Inheritance in the Entity Framework

Fakher Halim — Tue, 15 Jul 2008 17:28:49 GMT

A working example of Table per Hierarchy for Visual Studio 2008 SP1 is available at

http://www.codeproject.com/KB/architecture/LinqEntityFramework.aspx

re: Inheritance in the Entity Framework

Hitesh — Thu, 04 Sep 2008 14:02:08 GMT

Hi There,

Good article on explanation of inheritance in entity framework..

I have a perticular sutuation where by , I have to inherit from a given entity solely for the purpose of adding more calculated fields .. and however DO NOT SAVE the inherited entity to database...

for .e.g.

I have an entity

"Contractor" which contains.. "HourlyRate" and "EstimatedHours"

and is working fine for saving these two values using entity framework...

However, I now NEED TO DEFINE an INHERITED entity for reporting purpose..

"EstimatedCotractorCost" which will inherit from "Contractor" entity and will have a field "EstimatedCost" which should be "HourlyRate * EstimatedHours" ...and should not be serialised.

how can i do that?

Your help would be much appriciated.

Hitesh.

re: Inheritance in the Entity Framework

Ricardo — Wed, 08 Oct 2008 21:02:59 GMT

How could I change the type of an object since the condition, ProductType, is not mapped to a property? For instance: I would like to save a RegularProduct as a DiscontinuedProduct. It´s is possible?

I´d appreciate if someone could answer this question.

Thanks,

Ricardo

New and Notable 149

Sam Gentile's Blog — Wed, 03 Dec 2008 18:01:53 GMT

Yup, I'm still stuck in Seattle and I still feel like crap. Tomas just went off to the airport and I feel like the last MVP left in Seattle. Just want to get out of here and home but can't do that until tomorrow night. Lots of stuff stored up Entity Framework/ADO.NET

re: Inheritance in the Entity Framework

Greg — Sat, 13 Dec 2008 21:25:55 GMT

I'm not finding a full example of how to model Table Per Concrete Type anywhere. I suppose the basic dilemma is how one models the column mappings of the properties in the abstract base type that one defines in the conceptual model, since any given one of those properties will be sourced from multiple tables.

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re: Inheritance in the Entity Framework

Richard Tang — Mon, 10 Aug 2009 19:19:42 GMT

My design is a typical "Table per Concrete Type". All entity classes are derived from an abstract base entity class. The properties in the base class are mapped to a each individual table.

The problem I have is that I have to manually edit the .edmx file with an XML editor to implement this. The Entity Data Model Designer can't open this type of .edmx files.

I tried the EF 4.0 CTP and Visual Studio 2010 beta, it seems to work the same way.

This is a huge problem to us because we won't be able maintain the data model with a designer and it adds lot of work load.

Would someone please explain to me why the designer is not supporting this common case?

Is there any other framework I can use to solve this problem?

Here is another MSDN thread about this problem:

http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/038d14e8-fc04-4b06-b1e4-d5b1a950a901

Any help will be appreciated.

Richard.

re: Inheritance in the Entity Framework

Tim — Tue, 11 Aug 2009 16:37:05 GMT

Why isn't there support to have one base-type that all Entities inherit from (EntityBase)? For example, if all my tables have a "ModifiedDate", why do I need to keep creating the same property over and over in all entity instances when they could just as easily inherit from one common base-type?