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morrisjdev / FileContextCore

FileContextCore is a "Database"-Provider for Entity Framework Core and adds the ability to store information in files instead of being limited to databases.
Apache License 2.0
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Cascade Support #12

Closed mguinness closed 4 years ago

mguinness commented 4 years ago

Thanks for creating this library which is great for demos and using this in IdentityManagerUI repo. Do you have any plans to support Cascade Delete? This causes issues since if a role in AspNetRoles is deleted then corresponding record in AspNetUserRoles is orphaned.

morrisjdev commented 4 years ago

Hi.

Good point. I will take a look if this is easily possible and will write you soon.

Thank you

mguinness commented 4 years ago

Thanks Morris, I appreciate you looking into this.

mguinness commented 4 years ago

@morrisjdev Were you able to investigate and see the level of difficulty involved?

morrisjdev commented 4 years ago

Hi @mguinness.

Sorry for the late reply. I was very busy in the last days.

I found the origin of the problem: FileContextCore uses a kind of lazy loading. That means that data are only loaded when they are needed. If you have data with references the referenced data are only loaded when you explicitly use .Include(...). If you delete data without loading the references FileContextCore never knows that there are data that have to get deleted too. In a relational database there are additional constraints that are defined on database side to avoid that problem but FileContextCore does not have them.

To use that feature you always have to make sure to load referenced data.

This for example works:

db.Users.RemoveRange(db.Users.Include(u => u.Entries));
db.SaveChanges();

Again sorry for the long response time.

Best regards.

Morris

mguinness commented 4 years ago

No problem Morris, thanks for taking the time to investigate. This appears to be a similar issue to Cascade Delete Support in the InMemory provider.