How to use Tagged<Tag, RawValue> (swift-tagged) with this library?

[fceruti]

If I only have sharing-grab as a dependency and try doing import Tagged, I get: No such module 'Tagged'. Which is weird since it's one of the dependencies added by sharing-grdb.

I tried adding https://github.com/pointfreeco/swift-structured-queries to Package.swift alongside sharing-grdb and setting the tagged trait, but that doesn't seem to work either.

Adding https://github.com/pointfreeco/swift-tagged to packages doesn't work either.

I'm out of ideas.

Is there something I'm missing? Is this feature not available with sharing-grdb?

[mbrandonw]

We have documentation on this here.

[fceruti]

I was using that as a reference. I've figured the problem, which was in Package.swift (I was close with my exploration, but not quite hitting it).

This is my original package:

// swift-tools-version: 6.1
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "MyApp",
	platforms: [.macOS(.v15)],
    products: [
        .library(
            name: "MyApp",
            targets: ["MyApp"]),
    ],
	dependencies: [
		.package(url: "https://github.com/pointfreeco/sharing-grdb.git", from: "0.4.0")
	],
    targets: [
        .target(
            name: "MyApp",
			dependencies: [
				.product(name: "SharingGRDB", package: "sharing-grdb")
			]
		),
        .testTarget(
            name: "MyAppTests",
            dependencies: ["MyApp"]
        ),
    ],
	swiftLanguageModes: [.v6]
)

Basically, you need to add both swift-tagged and swift-structured-queries as dependencies, since sharing-grdb does not "leak" them.

// swift-tools-version: 6.1
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "MyApp",
	platforms: [.macOS(.v15)],
    products: [
        .library(
            name: "MyApp",
            targets: ["MyApp"]),
    ],
	dependencies: [
		.package(
			url: "https://github.com/pointfreeco/swift-structured-queries",
			from: "0.5.0",
			traits: ["StructuredQueriesTagged"]
		),
		.package(url: "https://github.com/pointfreeco/sharing-grdb.git", from: "0.4.0"),
		.package(url: "https://github.com/pointfreeco/swift-tagged.git", from: "0.10.0")
	],
    targets: [
        .target(
            name: "MyApp",
			dependencies: [
				.product(name: "SharingGRDB", package: "sharing-grdb"),
				.product(name: "Tagged", package: "swift-tagged")
			]
		),
        .testTarget(
            name: "MyAppTests",
            dependencies: ["MyApp"]
        ),
    ],
	swiftLanguageModes: [.v6]
)

[Pomanks]

I followed the documentation and your implementation but when querying data I get errors related to Tagged & UUIDs.

For example:

try await database.read { [family] db in
  try !Family
      .find(db, id: family.id)
      .exists(db)
} // -> Key not found in table family: [id:Data(16 bytes)]

I'm not sure to understand why it won't handle the Tagged id or how to fix that 🤔

[mbrandonw]

Hi @Pomanks, the code snippet you shared is not using any of the tools from SharingGRDB or StructuredQueries. The find(_:id:) and exists(_:) methods come from GRDB proper. So there may be other steps you need to take to make it work with GRDB, or you can provide more info (like a repro) so that it is easier for someone to help.

[groue]

@Pomanks The proper way to add support to Tagged in GRDB is documented there. Your app has already performed this step, because your sample code compiles fine and fails at runtime.

Your sample code does not check if a Family exists.

It first loads a Family with find, which fails with error "Key not found" if the record does not exist in the database. That's what find(_:id:) does. Then, in case of find success (the record exists in the database), the sample code asks the fetched record if it is present in the database with exists(db) (the answer is obviously yes since it was just fetched).

As you can see, the logic is incorrect. Fix your code as below:

try await database.read { [family] db in
  // Ask the record type.
  try !Family.exists(db, id: family.id)
}

Or, if family is an instance of Family:

try await database.read { [family] db in
  // Ask the record instance.
  try !family.exists(db)
}

[Pomanks]

Hi @mbrandonw, my bad then! I think I saw this being used in one of your videos and got confused… thanks for clarifying.
Thanks @groue for the deep explanation and code sample, I better understand how find works now!
The latter is even more concise than what I used and works perfectly for my use case! 😄