Nullable Vec<u8> type

[angrynode]

On sea_orm 2 RC38.

I'm trying to implement a newtype that's not stringy, not an enum, but a binary type, TorrentFile.

I'm probably doing something wrong because i can't seem to be able to do Option<TorrentFile> in a sea_orm model. The type implements Nullable here.

In my model, i've tried to specify #[sea_orm(default_value = "None", nullable)] even though i don't think it would be necessary. In the migration, i've tried both var_binary(...).null() and binary(...).null()

The error i get at runtime is Type Error: A null value was encountered while decoding "resolved". It only occurs when loading the table, after a magnet was inserted with resolved = NULL.

My understanding is that this should only happening when encountering TryGetError::Null, but in that case the implementation for Option<T> should produce Ok(None).

There's probably something missing in my mental model. I'll be happy to help improve the docs about binary newtypes if i can understand what's wrong :)

I've added the label "bug" because it's a runtime error and not a compile-time error.

[Huliiiiii]

Does let val: Vec<u8> = res.try_get_by_nullable(index)?; work?

[angrynode]

That appears to solve the issue, thanks (i haven't tried yet setting it to Some and seeing if that fails something else). Does that mean that types which derive DeriveValueType do not support Option<T> because the macro doesn't seem to use try_get_by_nullable? (i will perform more tests and report)

Does that mean all types should use try_get_by_nullable and never try_get_by in the TryGetable::try_get_by implementation? Or is there a case where not supporting Option is a feature?

EDIT: It looks like stringy types with DeriveValueType do support Option<T> although like i said i don't really understand why because they don't use try_get_by_nullable.

[angrynode]

I opened a PR to the docs so other users won't be as confused as me here: SeaQL/seaql.github.io#177

[Huliiiiii]

https://github.com/SeaQL/seaql.github.io/pull/177/changes#r3258505267

The recommended approach is to use let bytes = <Vec<u8> as sea_orm::TryGetable>::try_get_by(res, index)?;. This is equivalent to res.try_get_by_nullable.

res.try_get_by will convert null to DbErr, while other methods will return TryGetError, which transparently forwards null cases.

[angrynode]

Closing this issue in favor of: SeaQL/seaql.github.io#177