#1652 - Tighten contracts for parameter values in MethodLinkBuilderFactory.linkTo(…).

If a parameter array is given to MethodLinkBuilderFactory.linkTo(…) methods, we now verify its correct length in correspondence to the method given. If no parameters are given at all, we automatically create a parameter value array of the required length.

src/main/java/org/springframework/hateoas/server/MethodLinkBuilderFactory.java

@@ -30,7 +30,18 @@ public interface MethodLinkBuilderFactory<T extends LinkBuilder> extends LinkBui
 
 	/**
 	 * Returns a {@link LinkBuilder} pointing to the URI mapped to the given {@link Method} and expanding this mapping
-	 * using the given parameters.
+	 * using {@literal null} values as parameters.
+	 *
+	 * @param method must not be {@literal null}.
+	 * @return
+	 * @since 1.4
+	 */
+	T linkTo(Method method);
+
+	/**
+	 * Returns a {@link LinkBuilder} pointing to the URI mapped to the given {@link Method} and expanding this mapping
+	 * using the given parameters. The number of parameter values has to match the length of the given method's expected
+	 * parameters.
 	 *
 	 * @param method must not be {@literal null}.
 	 * @param parameters
@@ -40,7 +51,19 @@ public interface MethodLinkBuilderFactory<T extends LinkBuilder> extends LinkBui
 
 	/**
 	 * Returns a {@link LinkBuilder} pointing to the URI mapped to the given {@link Method} assuming it was invoked on an
-	 * object of the given type.
+	 * object of the given type expanding the mapping using {@literal null} values as parameters.
+	 *
+	 * @param type must not be {@literal null}.
+	 * @param method must not be {@literal null}.
+	 * @return
+	 * @since 1.4
+	 */
+	T linkTo(Class<?> type, Method method);
+
+	/**
+	 * Returns a {@link LinkBuilder} pointing to the URI mapped to the given {@link Method} assuming it was invoked on an
+	 * object of the given type. The number of parameter values has to match the length of the given method's expected
+	 * parameters.
 	 *
 	 * @param type must not be {@literal null}.
 	 * @param method must not be {@literal null}.

src/main/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilder.java

@@ -116,6 +116,16 @@ public class WebMvcLinkBuilder extends TemplateVariableAwareLinkBuilderSupport<W
 		return new WebMvcLinkBuilder(UriComponentsBuilderFactory.getComponents()).slash(uriComponents, true);
 	}
 
+	/*
+	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(Method)
+	 */
+	public static WebMvcLinkBuilder linkTo(Method method) {
+
+		Assert.notNull(method, "Method must not be null!");
+
+		return linkTo(method.getDeclaringClass(), method, new Object[method.getParameterTypes().length]);
+	}
+
 	/*
 	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(Method, Object...)
 	 */
@@ -127,6 +137,17 @@ public class WebMvcLinkBuilder extends TemplateVariableAwareLinkBuilderSupport<W
 		return linkTo(method.getDeclaringClass(), method, parameters);
 	}
 
+	/*
+	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(Class<?>, Method)
+	 */
+	public static WebMvcLinkBuilder linkTo(Class<?> controller, Method method) {
+
+		Assert.notNull(controller, "Controller type must not be null!");
+		Assert.notNull(method, "Method must not be null!");
+
+		return linkTo(controller, method, new Object[method.getParameterTypes().length]);
+	}
+
 	/*
 	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(Class<?>, Method, Object...)
 	 */
@@ -136,6 +157,12 @@ public class WebMvcLinkBuilder extends TemplateVariableAwareLinkBuilderSupport<W
 		Assert.notNull(method, "Method must not be null!");
 		Assert.notNull(parameters, "Parameters must not be null!");
 
+		int expected = method.getParameterTypes().length;
+		int given = parameters.length;
+
+		Assert.isTrue(expected == given,
+				() -> String.format("Incorrect number of parameter values given. Expected %s, got %s!", expected, given));
+
 		return linkTo(DummyInvocationUtils.getLastInvocationAware(controller, method, parameters));
 	}
 

src/main/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderFactory.java

@@ -103,6 +103,33 @@ public class WebMvcLinkBuilderFactory implements MethodLinkBuilderFactory<WebMvc
 		return WebMvcLinkBuilder.linkTo(controller, parameters);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.server.MethodLinkBuilderFactory#linkTo(java.lang.reflect.Method)
+	 */
+	@Override
+	public WebMvcLinkBuilder linkTo(Method method) {
+		return WebMvcLinkBuilder.linkTo(method);
+	}
+
+	/*
+	 * (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);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.server.MethodLinkBuilderFactory#linkTo(java.lang.Class, java.lang.reflect.Method)
+	 */
+	@Override
+	public WebMvcLinkBuilder linkTo(Class<?> type, Method method) {
+		return WebMvcLinkBuilder.linkTo(type, method);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.hateoas.MethodLinkBuilderFactory#linkTo(java.lang.Class, java.lang.reflect.Method, java.lang.Object[])
@@ -161,15 +188,6 @@ public class WebMvcLinkBuilderFactory implements MethodLinkBuilderFactory<WebMvc
 		}, builderFactory, getConversionService());
 	}
 
-	/*
-	 * (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 Supplier<ConversionService> getConversionService() {
 
 		return () -> {

src/test/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilderUnitTest.java

@@ -30,6 +30,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Stream;
 
+import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
 import org.junit.jupiter.api.Test;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.support.ConfigurableConversionService;
@@ -674,6 +675,24 @@ class WebMvcLinkBuilderUnitTest extends TestUtils {
 		assertThat(result.getHref()).endsWith("?param=first");
 	}
 
+	@Test // #1652
+	void buildsLinkWithoutParameterValuesGiven() throws Exception {
+
+		Method method = ControllerWithMethods.class.getDeclaredMethod("myMethod", Object.class);
+
+		Stream.<ThrowingCallable> of( //
+				() -> linkTo(method, new Object[0]), //
+				() -> linkTo(ControllerWithMethods.class, method, new Object[0]) //
+		) //
+				.map(assertThatIllegalArgumentException()::isThrownBy)
+				.forEach(it -> it.withMessageContaining("Expected 1, got 0"));
+
+		Stream.<ThrowingCallable> of( //
+				() -> linkTo(method), //
+				() -> linkTo(ControllerWithMethods.class, method) //
+		).forEach(assertThatNoException()::isThrownBy);
+	}
+
 	private static UriComponents toComponents(Link link) {
 		return UriComponentsBuilder.fromUriString(link.expand().getHref()).build();
 	}