Make LastInsertIDInitializable public

[t-ae]

I'm planning to have indivisual ID types for each models.
For example:

struct MyModelID: Codable, Hashable, RawRepresenatable, LosslessStringConvertible {
    var id: Int

    ...
}

final class MyModel: Model {
    @ID(custom: "id", generatedBy: .database)
    var id: MyModelID?

    ...
}

It seems most Fluent futures works well, but I found a problem.

id of MyModel is auto incrementing INT column, so it should be set after the model is saved.
Unfortunately, if the type of id does not conform to LastInsertIDInitializable, the program crashes at here:

fluent-mysql-driver/Sources/FluentMySQLDriver/FluentMySQLDatabase.swift

Lines 149 to 153 in 900c4c6

	if let lastInsertIDInitializable = T.self as? LastInsertIDInitializable.Type {
	return lastInsertIDInitializable.init(lastInsertID: self.metadata.lastInsertID!) as! T
	} else {
	fatalError("Unsupported database generated identifier type: \(T.self).")
	}

To make matter worse, MyModelID cannot confrom to LastInsertIDInitializable because it is internal.

fluent-mysql-driver/Sources/FluentMySQLDriver/FluentMySQLDatabase.swift

Lines 157 to 159 in 900c4c6

	protocol LastInsertIDInitializable {
	init(lastInsertID: UInt64)
	}

I want it to be public.

Also I want to hear your opinion about using custom types as ID.
I think its good idea but haven't gone deep yet.

[0xTim]

Why do you want to use a custom type for the ID? I can see this breaking a lot of Fluent, including the relationships and querying since Fluent won't know what underlying DB type to map to in the encoder/decoder

[t-ae]

The main reason is that it is easy to misuse if all models have same ID type.
The IDs of ModelA and ModelB is similar but they are different. ModelA.find(idOfModelB, on: db) is totally incorrect operation.
I want to forbid it with type system.

I can see this breaking a lot of Fluent, including the relationships and querying since Fluent won't know what underlying DB type to map to in the encoder/decoder

That's correct. I didn't noticed simply making LastInsertIDInitializable public causes several problem.
There's no restriction LastInsertIDInitializable will be encoded to integer.
As far as I know there's no way in type system to assure the underlying type so protocol approach won't work.

The only way that can achieve my demand is having ID type in this repository but it's going too far.
I give up this issue.
If someone has good idea, please tell me.