fix generic constraint type

[matthyk]

Since find-my-way version 4.1 it is possible to specify a generic type for the value of a constraint. The default type of this generic parameter is string. This makes it impossible to register constraints that have a value type other than string. The following example produces the error Type 'ConstraintStrategy<HTTPVersion.V1, number>' is not assignable to type 'ConstraintStrategy<HTTPVersion.V1, string>'. Type 'number' is not assignable to type 'string'..

import fastify from 'fastify'
import { ConstraintStrategy, HTTPVersion, Req, Handler} from 'find-my-way'

const constraintStrategy: ConstraintStrategy<HTTPVersion.V1, number> = {
  deriveConstraint<Context>(req: Req<HTTPVersion.V1>, ctx: Context | undefined): number {
    return 0
  },
  mustMatchWhenDerived: false,
  name: "myStrategy",
  storage() {
    return {
      get(value: number): Handler<HTTPVersion.V1> | null {
        return null
      },
      set(value: number, handler: Handler<HTTPVersion.V1>): void {},
      del(value: number): void {},
      empty(): void {}
    }
  },
  validate(value: unknown): void {
  }
}

const app = fastify({
  constraints: {
    constraintStrategy
  }
})

Setting the generic type to unknown solves this issue.

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[mcollina]

lgtm

[fstoerkle]

This change is not compatible with find-my-way@4.0.0, I encounter this error when running tsc:

Error: node_modules/fastify/fastify.d.ts(125,21): error TS2314: Generic type 'ConstraintStrategy<V>' requires 1 type argument(s).

Upgrading find-my-way to 4.3.3 fixed this for me.

Shouldn‘t the minimum version of find-my-way be updated to 4.1.0 in fastify's package.json?

[matthyk]

I think you're right. We should upgrade to find-my-way version 4.1.0.

[github-actions]

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