Is it possible for a LINQ to SQL discriminator column to be non-inheriting?

Data and Databases
1

I’m working on a database and LINQ to SQL web app using ASP.NET. My setup includes two types of pages: standard and root. The database has separate tables for Page and RootPage:

Page Table:
- PageId (PK)
- HtmlTitle
- PageHeading
- MetaDescription
- IsRoot

RootPage Table:
- PageId (FK, PK)
- FavIcon
- StyleSheet
- MasterPage

I’ve set the IsDiscriminator property for the IsRoot column in my DBML file. I’m hoping this will make the RootPage class inherit from Page.

What I want to do is something like this:

var roots = db.Pages.OfType<RootPage>();

// Or

RootPage newRoot = new RootPage {
    HtmlTitle = "Home",
    FavIcon = "main.ico"
};
db.Pages.Add(newRoot);
db.SaveChanges();

My question is: Can the IsDiscriminator column be nullable or false? Will this setup work as expected?

2

hey, i’ve used linq to sql before and ur setup looks alright. but discriminator columns usually cant be nullable, it might mess up inheritance. try using a non-nullable int column than bool? like pageType=1 for normal, pageType=2 for root. that way u can add more types if needed

3

While your approach is on the right track, there are a few considerations to keep in mind with LINQ to SQL discriminators. Typically, the discriminator column should be non-nullable to ensure proper inheritance mapping. Having it nullable or set to false could lead to unexpected behavior during querying and object instantiation.

Instead of using IsRoot as a discriminator, consider a more explicit approach. Creating a PageType column in the Page table with values such as ‘Standard’ and ‘Root’ would offer clearer separation and allow for future expansion as needed.

For your use case, exploring Table-Per-Type (TPT) inheritance in Entity Framework might provide a cleaner separation between the Page and RootPage entities while maintaining the desired functionality.