Template variables SPI

reda-alaoui · reda-alaoui · commit af4ea4960808 · 2020-08-02T23:11:14.000+02:00
diff --git a/src/main/java/org/springframework/hateoas/server/core/AdditionalUriHandler.java b/src/main/java/org/springframework/hateoas/server/core/AdditionalUriHandler.java
@@ -0,0 +1,15 @@
+package org.springframework.hateoas.server.core;
+
+import org.springframework.hateoas.TemplateVariables;
+import org.springframework.web.util.UriComponents;
+import org.springframework.web.util.UriComponentsBuilder;
+
+/**
+ * @author Réda Housni Alaoui
+ */
+public interface AdditionalUriHandler {
+
+	UriComponentsBuilder apply(UriComponentsBuilder uriComponentsBuilder, MethodInvocation methodInvocation);
+
+	TemplateVariables apply(TemplateVariables templateVariables, UriComponents uriComponents, MethodInvocation methodInvocation);
+}
diff --git a/src/main/java/org/springframework/hateoas/server/core/WebHandler.java b/src/main/java/org/springframework/hateoas/server/core/WebHandler.java
@@ -24,7 +24,6 @@
 import java.lang.reflect.Method;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
@@ -56,6 +55,7 @@
  *
  * @author Greg Turnquist
  * @author Oliver Drotbohm
+ * @author Réda Housni Alaoui
  */
 public class WebHandler {
 
@@ -75,20 +75,19 @@ public interface PreparedWebHandler<T extends LinkBuilder> {
 
 	public static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invocationValue,
 			LinkBuilderCreator<T> creator) {
-		return linkTo(invocationValue, creator,
-				(BiFunction<UriComponentsBuilder, MethodInvocation, UriComponentsBuilder>) null);
+		return linkTo(invocationValue, creator, null);
 	}
 
 	public static <T extends LinkBuilder> T linkTo(Object invocationValue, LinkBuilderCreator<T> creator,
-			@Nullable BiFunction<UriComponentsBuilder, MethodInvocation, UriComponentsBuilder> additionalUriHandler,
+			@Nullable AdditionalUriHandler additionalUriHandler,
 			Function<String, UriComponentsBuilder> finisher) {
 
 		return linkTo(invocationValue, creator, additionalUriHandler).conclude(finisher);
 	}
 
 	private static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invocationValue,
 			LinkBuilderCreator<T> creator,
-			@Nullable BiFunction<UriComponentsBuilder, MethodInvocation, UriComponentsBuilder> additionalUriHandler) {
+			@Nullable AdditionalUriHandler additionalUriHandler) {
 
 		Assert.isInstanceOf(LastInvocationAware.class, invocationValue);
 
@@ -150,7 +149,9 @@ private static <T extends LinkBuilder> PreparedWebHandler<T> linkTo(Object invoc
 					? builder.buildAndExpand(values) //
 					: additionalUriHandler.apply(builder, invocation).buildAndExpand(values);
 
-			TemplateVariables variables = NONE;
+			TemplateVariables variables = additionalUriHandler == null
+					? NONE
+					: additionalUriHandler.apply(NONE, components, invocation);
 
 			for (String parameter : optionalEmptyParameters) {
 
diff --git a/src/main/java/org/springframework/hateoas/server/mvc/UriComponentsContributor.java b/src/main/java/org/springframework/hateoas/server/mvc/UriComponentsContributor.java
@@ -15,10 +15,16 @@
  */
 package org.springframework.hateoas.server.mvc;
 
+import java.util.Collection;
+import java.util.Collections;
+
 import org.springframework.core.MethodParameter;
+import org.springframework.hateoas.TemplateVariable;
+import org.springframework.hateoas.TemplateVariables;
 import org.springframework.hateoas.server.MethodLinkBuilderFactory;
 import org.springframework.lang.Nullable;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 
 /**
@@ -28,6 +34,7 @@
  *
  * @see MethodLinkBuilderFactory#linkTo(Object)
  * @author Oliver Gierke
+ * @author Réda Housni Alaoui
  */
 public interface UriComponentsContributor {
 
@@ -47,4 +54,15 @@ public interface UriComponentsContributor {
 	 * @param value can be {@literal null}.
 	 */
 	void enhance(UriComponentsBuilder builder, @Nullable MethodParameter parameter, @Nullable Object value);
+
+	/**
+	 * Enhance the given {@link TemplateVariables}
+	 *
+	 * @param templateVariables will never be {@literal null}.
+	 * @param uriComponents will never be {@literal null}.
+	 * @param parameter can be {@literal null}.
+	 */
+	default TemplateVariables enhance(TemplateVariables templateVariables, UriComponents uriComponents, @Nullable MethodParameter parameter){
+		return templateVariables;
+	}
 }
diff --git a/src/main/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderFactory.java b/src/main/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderFactory.java
@@ -26,10 +26,14 @@
 
 import org.springframework.core.MethodParameter;
 import org.springframework.hateoas.Link;
+import org.springframework.hateoas.TemplateVariables;
 import org.springframework.hateoas.server.MethodLinkBuilderFactory;
+import org.springframework.hateoas.server.core.AdditionalUriHandler;
 import org.springframework.hateoas.server.core.LinkBuilderSupport;
+import org.springframework.hateoas.server.core.MethodInvocation;
 import org.springframework.hateoas.server.core.MethodParameters;
 import org.springframework.hateoas.server.core.WebHandler;
+import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 
 /**
@@ -44,6 +48,7 @@
  * @author Kevin Conaway
  * @author Andrew Naydyonock
  * @author Greg Turnquist
+ * @author Réda Housni Alaoui
  */
 public class WebMvcLinkBuilderFactory implements MethodLinkBuilderFactory<WebMvcLinkBuilder> {
 
@@ -106,8 +111,29 @@ public WebMvcLinkBuilder linkTo(Object invocationValue) {
 		Function<String, UriComponentsBuilder> builderFactory = mapping -> UriComponentsBuilderFactory.getBuilder()
 				.path(mapping);
 
-		return WebHandler.linkTo(invocationValue, WebMvcLinkBuilder::new, (builder, invocation) -> {
+		return WebHandler.linkTo(invocationValue, WebMvcLinkBuilder::new,
+				new UriComponentsContributorsAdditionalUriHandler(uriComponentsContributors), builderFactory);
+	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(java.lang.reflect.Method, java.lang.Object[])
+	 */
+	@Override
+	public WebMvcLinkBuilder linkTo(Method method, Object... parameters) {
+		return WebMvcLinkBuilder.linkTo(method, parameters);
+	}
+
+	private static class UriComponentsContributorsAdditionalUriHandler implements AdditionalUriHandler {
+
+		private final List<UriComponentsContributor> uriComponentsContributors;
+
+		private UriComponentsContributorsAdditionalUriHandler(List<UriComponentsContributor> uriComponentsContributors) {
+			this.uriComponentsContributors = uriComponentsContributors;
+		}
+
+		@Override
+		public UriComponentsBuilder apply(UriComponentsBuilder builder, MethodInvocation invocation) {
 			MethodParameters parameters = MethodParameters.of(invocation.getMethod());
 			Iterator<Object> parameterValues = Arrays.asList(invocation.getArguments()).iterator();
 
@@ -123,16 +149,22 @@ public WebMvcLinkBuilder linkTo(Object invocationValue) {
 			}
 
 			return builder;
+		}
 
-		}, builderFactory);
-	}
+		@Override
+		public TemplateVariables apply(TemplateVariables templateVariables, UriComponents uriComponents, MethodInvocation invocation) {
+			MethodParameters parameters = MethodParameters.of(invocation.getMethod());
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(java.lang.reflect.Method, java.lang.Object[])
-	 */
-	@Override
-	public WebMvcLinkBuilder linkTo(Method method, Object... parameters) {
-		return WebMvcLinkBuilder.linkTo(method, parameters);
+			for (MethodParameter parameter : parameters.getParameters()) {
+
+				for (UriComponentsContributor contributor : uriComponentsContributors) {
+					if (contributor.supportsParameter(parameter)) {
+						templateVariables = contributor.enhance(templateVariables, uriComponents, parameter);
+					}
+				}
+			}
+
+			return templateVariables;
+		}
 	}
 }
diff --git a/src/test/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderFactoryUnitTest.java b/src/test/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderFactoryUnitTest.java
@@ -31,6 +31,8 @@
 import org.springframework.format.annotation.DateTimeFormat.ISO;
 import org.springframework.hateoas.IanaLinkRelations;
 import org.springframework.hateoas.Link;
+import org.springframework.hateoas.TemplateVariable;
+import org.springframework.hateoas.TemplateVariables;
 import org.springframework.hateoas.TestUtils;
 import org.springframework.hateoas.server.mvc.WebMvcLinkBuilderUnitTest.ControllerWithMethods;
 import org.springframework.hateoas.server.mvc.WebMvcLinkBuilderUnitTest.PersonControllerImpl;
@@ -41,6 +43,7 @@
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 
 /**
@@ -50,6 +53,7 @@
  * @author Oliver Gierke
  * @author Kamill Sokol
  * @author Ross Turner
+ * @author Réda Housni Alaoui
  */
 class WebMvcLinkBuilderFactoryUnitTest extends TestUtils {
 
@@ -174,6 +178,17 @@ void createsLinkToParameterizedControllerRootWithParameterMap() {
 		assertThat(link.getHref()).endsWith("/people/17/addresses");
 	}
 
+	@Test
+	void appliesTemplateVariableIfContributorConfigured() {
+
+		WebMvcLinkBuilderFactory factory = new WebMvcLinkBuilderFactory();
+		factory.setUriComponentsContributors(Collections.singletonList(new SampleUriComponentsContributor()));
+
+		Link link = factory.linkTo(methodOn(SampleController.class).sampleMethod(1L, null)).withSelfRel();
+		assertPointsToMockServer(link);
+		assertThat(link.getHref()).endsWith("/sample/1{?foo}");
+	}
+
 	interface SampleController {
 
 		@RequestMapping("/sample/{id}")
@@ -198,8 +213,19 @@ public boolean supportsParameter(MethodParameter parameter) {
 
 		@Override
 		public void enhance(UriComponentsBuilder builder, MethodParameter parameter, Object value) {
+			if (value == null) {
+				return;
+			}
 			builder.queryParam("foo", ((SpecialType) value).parameterValue);
 		}
+
+		@Override
+		public TemplateVariables enhance(TemplateVariables templateVariables, UriComponents uriComponents, MethodParameter parameter) {
+			if (uriComponents.getQueryParams().containsKey("foo")) {
+				return templateVariables;
+			}
+			return templateVariables.concat(TemplateVariable.requestParameter("foo"));
+		}
 	}
 
 	static class SpecialType {
