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#118 - Use MVC ConversionService for parameter binding in link creation.
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We now look up the ConversionService available in the ApplicationContext from Web(Mvc|Flux)LinkBuilder. Some API tweaks to WebHandler to allow the lookup from the current request. The general fallback is now the invocation of …toString() on the parameter value.

Fixes #118, #352, #144, #149.
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@odrotbohm
odrotbohm committed Jan 25, 2021
1 parent 3da23a7 commit d0ff83c
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Showing 5 changed files with 193 additions and 43 deletions.
31 changes: 15 additions & 16 deletions src/main/java/org/springframework/hateoas/server/core/WebHandler.java
View file
Expand Up @@ -26,12 +26,12 @@
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;

import org.springframework.core.MethodParameter;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.format.support.DefaultFormattingConversionService;
import org.springframework.hateoas.Affordance;
import org.springframework.hateoas.TemplateVariable;
import org.springframework.hateoas.TemplateVariables;
Expand Down Expand Up @@ -71,7 +71,7 @@ public interface LinkBuilderCreator<T extends LinkBuilder> {
}

public interface PreparedWebHandler<T extends LinkBuilder> {
T conclude(Function<String, UriComponentsBuilder> finisher);
T conclude(Function<String, UriComponentsBuilder> finisher, ConversionService conversionService);
}

public static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invocationValue,
Expand All @@ -82,9 +82,9 @@ public static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invoca

public static <T extends LinkBuilder> T linkTo(Object invocationValue, LinkBuilderCreator<T> creator,
@Nullable BiFunction<UriComponentsBuilder, MethodInvocation, UriComponentsBuilder> additionalUriHandler,
Function<String, UriComponentsBuilder> finisher) {
Function<String, UriComponentsBuilder> finisher, Supplier<ConversionService> conversionService) {

return linkTo(invocationValue, creator, additionalUriHandler).conclude(finisher);
return linkTo(invocationValue, creator, additionalUriHandler).conclude(finisher, conversionService.get());
}

private static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invocationValue,
Expand All @@ -104,7 +104,7 @@ private static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invoc

String mapping = DISCOVERER.getMapping(invocation.getTargetType(), invocation.getMethod());

return finisher -> {
return (finisher, conversionService) -> {

UriComponentsBuilder builder = finisher.apply(mapping);
UriTemplate template = UriTemplateFactory.templateFor(mapping == null ? "/" : mapping);
Expand All @@ -120,16 +120,18 @@ private static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invoc

HandlerMethodParameters parameters = HandlerMethodParameters.of(invocation.getMethod());
Object[] arguments = invocation.getArguments();
ConversionService resolved = conversionService;

for (HandlerMethodParameter parameter : parameters.getParameterAnnotatedWith(PathVariable.class, arguments)) {
values.put(parameter.getVariableName(), encodePath(parameter.getValueAsString(arguments)));
values.put(parameter.getVariableName(),
encodePath(parameter.getValueAsString(arguments, resolved)));
}

List<String> optionalEmptyParameters = new ArrayList<>();

for (HandlerMethodParameter parameter : parameters.getParameterAnnotatedWith(RequestParam.class, arguments)) {

bindRequestParameters(builder, parameter, arguments);
bindRequestParameters(builder, parameter, arguments, conversionService);

if (SKIP_VALUE.equals(parameter.getVerifiedValue(arguments))) {

Expand Down Expand Up @@ -177,7 +179,7 @@ private static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invoc
*/
@SuppressWarnings("unchecked")
private static void bindRequestParameters(UriComponentsBuilder builder, HandlerMethodParameter parameter,
Object[] arguments) {
Object[] arguments, ConversionService conversionService) {

Object value = parameter.getVerifiedValue(arguments);

Expand Down Expand Up @@ -223,7 +225,7 @@ private static void bindRequestParameters(UriComponentsBuilder builder, HandlerM

} else {
if (key != null) {
builder.queryParam(key, encodeParameter(parameter.getValueAsString(arguments)));
builder.queryParam(key, encodeParameter(parameter.getValueAsString(arguments, conversionService)));
}
}
}
Expand Down Expand Up @@ -335,7 +337,6 @@ public List<HandlerMethodParameter> getParameterAnnotatedWith(Class<? extends An

private abstract static class HandlerMethodParameter {

private static final ConversionService CONVERSION_SERVICE = new DefaultFormattingConversionService();
private static final TypeDescriptor STRING_DESCRIPTOR = TypeDescriptor.valueOf(String.class);
private static final Map<Class<? extends Annotation>, Function<MethodParameter, ? extends HandlerMethodParameter>> FACTORY;
private static final String NO_PARAMETER_NAME = "Could not determine name of parameter %s! Make sure you compile with parameter information or explicitly define a parameter name in %s.";
Expand Down Expand Up @@ -400,7 +401,7 @@ public String getVariableName() {
return variableName;
}

public String getValueAsString(Object[] values) {
public String getValueAsString(Object[] values, ConversionService conversionService) {

Object value = values[parameter.getParameterIndex()];

Expand All @@ -414,11 +415,9 @@ public String getValueAsString(Object[] values) {

value = ObjectUtils.unwrapOptional(value);

// Try to lookup ConversionService from the request's context

// Guard with ….canConvert(…)
// if not, fall back to ….toString();
Object result = CONVERSION_SERVICE.convert(value, typeDescriptor, STRING_DESCRIPTOR);
Object result = conversionService.canConvert(typeDescriptor, STRING_DESCRIPTOR)
? conversionService.convert(value, typeDescriptor, STRING_DESCRIPTOR)
: value == null ? null : value.toString();

if (result == null) {
throw new IllegalArgumentException(String.format("Conversion of value %s resulted in null!", value));
Expand Down
34 changes: 33 additions & 1 deletion src/main/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderFactory.java
View file
Expand Up @@ -23,13 +23,23 @@
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.function.Supplier;

import javax.servlet.ServletContext;

import org.springframework.core.MethodParameter;
import org.springframework.core.convert.ConversionService;
import org.springframework.format.support.DefaultFormattingConversionService;
import org.springframework.hateoas.Link;
import org.springframework.hateoas.server.MethodLinkBuilderFactory;
import org.springframework.hateoas.server.core.LinkBuilderSupport;
import org.springframework.hateoas.server.core.MethodParameters;
import org.springframework.hateoas.server.core.WebHandler;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.util.UriComponentsBuilder;

/**
Expand All @@ -47,6 +57,8 @@
*/
public class WebMvcLinkBuilderFactory implements MethodLinkBuilderFactory<WebMvcLinkBuilder> {

private static ConversionService FALLBACK_CONVERSION_SERVICE = new DefaultFormattingConversionService();

private List<UriComponentsContributor> uriComponentsContributors = new ArrayList<>();

/**
Expand Down Expand Up @@ -124,7 +136,7 @@ public WebMvcLinkBuilder linkTo(Object invocationValue) {

return builder;

}, builderFactory);
}, builderFactory, getConversionService());
}

/*
Expand All @@ -135,4 +147,24 @@ public WebMvcLinkBuilder linkTo(Object invocationValue) {
public WebMvcLinkBuilder linkTo(Method method, Object... parameters) {
return WebMvcLinkBuilder.linkTo(method, parameters);
}

@SuppressWarnings("null")
private Supplier<ConversionService> getConversionService() {

return () -> {

RequestAttributes attributes = RequestContextHolder.getRequestAttributes();

if (!ServletRequestAttributes.class.isInstance(attributes)) {
return null;
}

ServletContext servletContext = ((ServletRequestAttributes) attributes).getRequest().getServletContext();
WebApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);

return context == null || !context.containsBean("mvcConversionService")
? FALLBACK_CONVERSION_SERVICE
: context.getBean("mvcConversionService", ConversionService.class);
};
}
}
70 changes: 45 additions & 25 deletions src/main/java/org/springframework/hateoas/server/reactive/WebFluxLinkBuilder.java
View file
Expand Up @@ -22,6 +22,9 @@
import java.util.List;
import java.util.function.Function;

import org.springframework.context.ApplicationContext;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.hateoas.Affordance;
import org.springframework.hateoas.IanaLinkRelations;
import org.springframework.hateoas.Link;
Expand Down Expand Up @@ -75,7 +78,7 @@ public static WebFluxBuilder linkTo(Object invocation) {
* @param exchange must not be {@literal null}.
*/
public static WebFluxBuilder linkTo(Object invocation, ServerWebExchange exchange) {
return new WebFluxBuilder(linkToInternal(invocation, Mono.just(getBuilder(exchange))));
return new WebFluxBuilder(linkToInternal(invocation, CurrentRequest.of(exchange)));
}

/**
Expand All @@ -87,7 +90,6 @@ public static WebFluxBuilder linkTo(Object invocation, ServerWebExchange exchang
* @return
*/
public static <T> T methodOn(Class<T> controller, Object... parameters) {

return DummyInvocationUtils.methodOn(controller, parameters);
}

Expand Down Expand Up @@ -245,40 +247,58 @@ public Mono<Link> toMono(Function<Link, Link> finisher) {
}
}

private static Mono<WebFluxLinkBuilder> linkToInternal(Object invocation) {

return linkToInternal(invocation,
Mono.deferContextual(
context -> CurrentRequest.of(context.getOrDefault(EXCHANGE_CONTEXT_ATTRIBUTE, null))));
}

private static Mono<WebFluxLinkBuilder> linkToInternal(Object invocation, Mono<CurrentRequest> builder) {

PreparedWebHandler<WebFluxLinkBuilder> handler = WebHandler.linkTo(invocation, WebFluxLinkBuilder::new);

return builder.map(it -> handler.conclude(path -> it.builder.path(path), it.conversionService));
}

/**
* Returns a {@link UriComponentsBuilder} obtained from the {@link ServerWebExchange}.
* Access to components we can obtain from the current request or fallbacks in case no current request is available.
*
* @param exchange
* @author Oliver Drotbohm
*/
private static UriComponentsBuilder getBuilder(@Nullable ServerWebExchange exchange) {
private static class CurrentRequest {

if (exchange == null) {
return UriComponentsBuilder.fromPath("/");
}
private static final ConversionService FALLBACK_CONVERSION_SERVICE = new DefaultConversionService();

ServerHttpRequest request = exchange.getRequest();
PathContainer contextPath = request.getPath().contextPath();
private UriComponentsBuilder builder;
private ConversionService conversionService;

return UriComponentsBuilder.fromHttpRequest(request) //
.replacePath(contextPath.toString()) //
.replaceQuery("");
}
public static Mono<CurrentRequest> of(@Nullable ServerWebExchange exchange) {

private static Mono<WebFluxLinkBuilder> linkToInternal(Object invocation) {
CurrentRequest result = new CurrentRequest();

return linkToInternal(invocation,
Mono.subscriberContext().map(context -> getBuilder(context.getOrDefault(EXCHANGE_CONTEXT_ATTRIBUTE, null))));
}
if (exchange == null) {

private static Mono<WebFluxLinkBuilder> linkToInternal(Object invocation, Mono<UriComponentsBuilder> builder) {
result.builder = UriComponentsBuilder.fromPath("/");
result.conversionService = FALLBACK_CONVERSION_SERVICE;

PreparedWebHandler<WebFluxLinkBuilder> handler = WebHandler.linkTo(invocation, WebFluxLinkBuilder::new);
return Mono.just(result);
}

return builder.map(WebFluxLinkBuilder::getBuilderCreator) //
.map(handler::conclude);
}
ServerHttpRequest request = exchange.getRequest();
PathContainer contextPath = request.getPath().contextPath();

result.builder = UriComponentsBuilder.fromHttpRequest(request) //
.replacePath(contextPath.toString()) //
.replaceQuery("");

ApplicationContext context = exchange.getApplicationContext();

private static Function<String, UriComponentsBuilder> getBuilderCreator(UriComponentsBuilder builder) {
return path -> builder.path(path);
result.conversionService = context != null && context.containsBean("webFluxConversionService")
? context.getBean("webFluxConversionService", ConversionService.class)
: FALLBACK_CONVERSION_SERVICE;

return Mono.just(result);
}
}
}
56 changes: 55 additions & 1 deletion src/test/java/org/springframework/hateoas/config/HypermediaWebFluxConfigurerTest.java
View file
Expand Up @@ -18,6 +18,7 @@
import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
import static org.assertj.core.api.AssertionsForInterfaceTypes.assertThat;
import static org.springframework.hateoas.config.EnableHypermediaSupport.HypermediaType.*;
import static org.springframework.hateoas.server.reactive.WebFluxLinkBuilder.*;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
Expand All @@ -31,6 +32,7 @@
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.format.FormatterRegistry;
import org.springframework.hateoas.CollectionModel;
import org.springframework.hateoas.EntityModel;
import org.springframework.hateoas.IanaLinkRelations;
Expand All @@ -41,7 +43,11 @@
import org.springframework.hateoas.server.core.TypeReferences.CollectionModelType;
import org.springframework.hateoas.server.core.TypeReferences.EntityModelType;
import org.springframework.hateoas.support.Employee;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.test.web.reactive.server.WebTestClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
Expand All @@ -50,6 +56,7 @@
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.reactive.config.EnableWebFlux;
import org.springframework.web.reactive.config.WebFluxConfigurer;

/**
* @author Greg Turnquist
Expand All @@ -67,7 +74,7 @@ void setUp(Class<?> context) {
ctx.register(context);
ctx.refresh();

HypermediaWebTestClientConfigurer configurer = ctx.getBean(HypermediaWebTestClientConfigurer.class);
HypermediaWebTestClientConfigurer configurer = ctx.getBean(HypermediaWebTestClientConfigurer.class);

this.testClient = WebTestClient.bindToApplicationContext(ctx).build().mutateWith(configurer);
}
Expand Down Expand Up @@ -322,6 +329,24 @@ void reactorTypesShouldWork() {
}).verifyComplete();
}

@Test // #118
void linkCreationConsidersRegisteredConverters() throws Exception {

setUp(WithConversionService.class);

this.testClient.get().uri("/sample/4711").exchange() //
.expectStatus().isEqualTo(HttpStatus.I_AM_A_TEAPOT) //
.returnResult(String.class).getResponseBody()
.as(StepVerifier::create)
.expectNextMatches(it -> {

assertThat(it).isEqualTo("/sample/sample");

return true;
})
.verifyComplete();
}

private void verifyRootUriServesHypermedia(MediaType mediaType) {
verifyRootUriServesHypermedia(mediaType, mediaType);
}
Expand Down Expand Up @@ -555,4 +580,33 @@ public void addLinks(CollectionModel<EntityModel<Employee>> resources) {
}
}

// #118

@Configuration
static class WithConversionService extends HalWebFluxConfig implements WebFluxConfigurer {

/*
* (non-Javadoc)
* @see org.springframework.web.servlet.config.annotation.WebMvcConfigurer#addFormatters(org.springframework.format.FormatterRegistry)
*/
@Override
public void addFormatters(FormatterRegistry registry) {
registry.addConverter(Sample.class, String.class, source -> "sample");
registry.addConverter(String.class, Sample.class, source -> new Sample());
}

static class Sample {}

@Controller
static class SampleController {

@GetMapping("/sample/{sample}")
Mono<HttpEntity<?>> sample(@PathVariable Sample sample) {

return linkTo(methodOn(SampleController.class).sample(new Sample())).withSelfRel()
.toMono()
.map(it -> new ResponseEntity<>(it.getHref(), HttpStatus.I_AM_A_TEAPOT));
}
}
}
}

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