fix(experimental): Functions for putting/getting an LDScopedClient from context.Context

[aengelberg]

This PR introduces a few more functions to the main ld package. This will allow Go developers to easily pass around a scoped client to any logic that already takes a context.Context.

In particular, this will make writing HTTP middleware that establishes an LD context pretty easy. The middleware just needs to create a scoped client with the LD context it wants, then pass that scoped client into the http.Request's built-in Go context.

func LDScopedClientMiddleware(client *LDClient) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			scopedClient := NewScopedClient(client, ldcontext.New("user-key"))
			ctx := GoContextWithScopedClient(r.Context(), scopedClient)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

func requestLogic(r *http.Request) {
	featureFlagEnabled := MustGetScopedClient(r.Context()).BoolVariation("my-flag", false)
	// use featureFlagEnabled...
}

[keelerm84]

bugbot run

[cursor]

Bug: Nil Client in Context Causes Panic

MustGetScopedClient returns nil without panicking if a typed nil *LDScopedClient is stored in the context. This occurs because GetScopedClient returns ok=true for a typed nil value, and GoContextWithScopedClient allows storing nil. Consequently, callers receive nil instead of a panic, leading to a later nil dereference at the point of use and defeating the "must" contract.

Additional Locations (1)

• ldclient_gocontext.go#L37-L41