How can I specify actual type of T on a ParameterizedTypeReference<T>?

Question

I have a controller defines following methods.

    Mono<EntityModel<Some>> readSome(...) {
        // works, simply.
    }

    Flux<EntityModel<Other>> readOther(...) {
        // works, simply.
    }

And, within my test class, I defined following methods that work.

    // WORKS!
    static List<EntityModel<Some>> readSome(...) {
        client...
                .exchange()
                .expectStatus().isOk()
                .expectBodyList(new TypeReferences.EntityModelType<Some>() {
                })
                .returnResult()
                .getResponseBody();
    }

    // WORKS!
    static List<EntityModel<Other>> readOther(...) {
        client...
                .exchange()
                .expectStatus().isOk()
                .expectBodyList(new TypeReferences.EntityModelType<Other>() {
                })
                .returnResult()
                .getResponseBody()
    }

And I naturally defined following method for all types.

As you can see, it's just a generic method for all types.

    private static <T> List<EntityModel<T>> readList(final WebTestClient client,
                                                     final Function<UriBuilder, URI> uriFunction,
                                                     @Nullable final String accept) {
        final var responseBody = client
                .get()
                .uri(uriFunction)
                .headers(h -> {
                    Optional.ofNullable(accept)
                            .map(MediaType::valueOf)
                            .map(List::of)
                            .ifPresent(h::setAccept);
                })
                .exchange()
                .expectStatus().isOk()
                .expectBodyList(new TypeReferences.EntityModelType<T>() { // NOT <T>, BUT Map
                })
                .returnResult()
                .getResponseBody();
        return Objects.requireNonNull(responseBody, "responseBody is null");
    }

Now, when I changed the readSome|readOther method with the readList method, I see a weird behavior.

The Jackson does not parse the content into the anymore, but a LinkedHashMap.

How can I specify Class<T> with the TypeReferences.EntityModelType<T>?

Answer 1

Try to make EntityModelType as a parameter of your method.

private static <T> List<EntityModel<T>> readList(
    TypeReferences.EntityModelType<T> entityType,
    final WebTestClient client,
    final Function<UriBuilder, URI> uriFunction,
    @Nullable final String accept
) {
        final var responseBody = client
                .get()
                .uri(uriFunction)
                .headers(h -> {
                    Optional.ofNullable(accept)
                            .map(MediaType::valueOf)
                            .map(List::of)
                            .ifPresent(h::setAccept);
                })
                .exchange()
                .expectStatus().isOk()
                .expectBodyList(entityType)
                .returnResult()
                .getResponseBody();
        return Objects.requireNonNull(responseBody, "responseBody is null");
    }

and then call it

readList(
    new TypeReferences.EntityModelType<Other>() {},
    .....
);

Hope it works.