Caught error: InvalidUUID()

[Pomanks]

Hi there,

Here's the context:
I'm using both SharingGRDB and GRDB in my project. Furthermore I'm using Tagged for my primary keys, configured as described in the documentation's section.

I also added some protocol conformances as described in GRDB's documentation.

But here's the thing: whenever I mix and match pure GRDB APIs with StructuredQueries APIs, I get the following error: Caught error: InvalidUUID()

This is coming from SharingGRDB's following function (in SQLiteQueryDecoder):

@inlinable
  mutating func decode(_ columnType: UUID.Type) throws -> UUID? {
    guard let uuidString = try decode(String.self) else { return nil }
    guard let uuid = UUID(uuidString: uuidString) else { throw InvalidUUID() }
    return uuid
  }

What I don't understand is when I don't mix those APIs it works perfectly fine! (I've tried that already, what I need to do is import the data and read it either from SharingGRDB only or GRDB only…)

Is there some limitations regarding UUIDs when using both libraries that I'm not aware of?
At the moment it's preventing me from using one or the other in my features and I can't find the cause or solution.

[mbrandonw]

Hi @Pomanks, are you writing to the database using GRDB’s tools and reading from the database using ours? If so, is there a chance the UUID is stored as bytes in your database? Our library assumes string UUIDs by default, with the option to store as bytes. You should be able to open your database to check how the data is stored.

Or if you provide a reproducing example we will take a look.

[Pomanks]

Hi @mbrandonw I am yes. And after checking this you're right, UUIDs are stored as data instead of plain text even though I'm explicitly setting TEXT as column type… 🤔

[mbrandonw]

It seems that bytes are always written to the database no matter what:

https://github.com/groue/GRDB.swift/blob/8ba1bc9a96afc731a000fd4136dd13a5a46297bd/GRDB/Core/Support/Foundation/UUID.swift#L50-L54

If you want to continue with this you can tell the @Table macro to use the data representation of UUIDs:

@Table struct Reminder {
  @Column(as: UUID.BytesRepresentation.self)
  let id: UUID
  // …
}

I also personally don't think it's worth storing UUIDs as bytes in the database. The biggest advantage is it's about half the size, but at the end of the day the size of IDs will pale in comparison to the size of the rest of your data. And the speed of inserts and selects is about the same for TEXT-based and BLOB-based UUIDs. But on the downside, it makes browsing and querying your database outside of the Swift tools a lot more difficult.

Also, is there a reason why you are mixing and matching the APIs?

[Pomanks]

I see.
Is there some equivalent API when using the Tagged library or should I fall back to using plain UUID for a while?

Yes, there is: I started my project long before StructuredQueries was released and wanted to migrate to StructuredQueries bit by bit.

[mbrandonw]

I haven't tested it, but this compiles and I believe should work:

@Table struct Reminder {
  @Column(as: Tagged<Self, UUID.BytesRepresentation>.self)
  let id: Tagged<Self, UUID>
  // …
}

Wanna give it a shot?

[Pomanks]

Well.. yes it does! This is awesome 🤩
Thanks a lot @mbrandonw!