DeleteBehaviorAttribute

[John0King]

Data annotations is a much easier way to configure model than Fluent API.
And we can only configure DeleteBehavior via Fluent API today, that means we need configure foreign key again in fluent api.
Can we have a DeleteBebaviorAttribute(DeleteBehavior behavior) in Microsoft.EntityFramework Namespace ?

[John0King]

see also in #10864

[Vekz]

Hey, I've wanted to take on the challange of implementing this.
This would've been my first ever issue done in open source community so please be understanding.

As far as I understand I should create DeleteBehaviorAttribute class in EFCore.Abstractions taking DeleteBehavior parameter in constructor (for now I've used int as I have trouble getting DeleteBehavior usings to EFCore.Abstractions) and storing it as a property.
And also create DeleteBehaviorAttributeConvention in EFCore/Metadata/Conventions and register it in ProviderConventionSetBuilder.

Could someone explain to me also how could I reference DeleteBehavior enum from inside of EFCore.Abstractions?

[ajcvickers]

@Vekz Sounds like a good plan. For the enum, move it to Abstractions and add type-forwarding to avoid a breaking change. For an example, search for TypeForwardedTo in the EF source.

[Vekz]

Okay, I've finished writing tests and figuring out how to put everything I've learned in past day so every case works.
And I managed to succeed.

Only this enum's left for me to implement. I'm gonna make PR probably later today. Thanks for really fast reply and pointing me to the solution.

[Vekz]

I didn't think I would get so much trouble from this TypeForwarding.

I get CS0012 on tests that build models from snapshot after I've done TypeForwarding.
Should I just add EFCore.Abstractions assembly reference to the test builder?

Sorry if it's stupid question this is actually first time I've ever touched TypeForwarding.

Update: I just added EFCore.Abstractions assembly reference in Bases for snapshot and migration tests and it fixed it

[Vekz]

@ajcvickers Could I ask you for a CR?
I know you are probably busy with other tasks and I don't expect PR being merged as it's not the most urgent feature on the list for sure.
But I would love to hear your feedback does the code meet all requirements or could I've done something better.