DATACMNS-867 - Optionals in CrudMethods API.

src/main/java/org/springframework/data/repository/core/CrudMethods.java

@@ -16,6 +16,7 @@
 package org.springframework.data.repository.core;
 
 import java.lang.reflect.Method;
+import java.util.Optional;
 
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
@@ -37,7 +38,7 @@ public interface CrudMethods {
 	 * @return the method to save entities or {@literal null} if noen exposed.
 	 * @see #hasSaveMethod()
 	 */
-	Method getSaveMethod();
+	Optional<Method> getSaveMethod();
 
 	/**
 	 * Returns whether the repository exposes a save method at all.
@@ -53,7 +54,7 @@ public interface CrudMethods {
 	 * @return the find all method of the repository or {@literal null} if not available.
 	 * @see #hasFindAllMethod()
 	 */
-	Method getFindAllMethod();
+	Optional<Method> getFindAllMethod();
 
 	/**
 	 * Returns whether the repository exposes a find all method at all.
@@ -69,7 +70,7 @@ public interface CrudMethods {
 	 * @return the find one method of the repository or {@literal null} if not available.
 	 * @see #hasFindOneMethod()
 	 */
-	Method getFindOneMethod();
+	Optional<Method> getFindOneMethod();
 
 	/**
 	 * Returns whether the repository exposes a find one method.
@@ -84,7 +85,7 @@ public interface CrudMethods {
 	 * @return the delete method of the repository or {@literal null} if not available.
 	 * @see #hasDelete()
 	 */
-	Method getDeleteMethod();
+	Optional<Method> getDeleteMethod();
 
 	/**
 	 * Returns whether the repository esposes a delete method.

src/main/java/org/springframework/data/repository/core/support/AbstractRepositoryMetadata.java

@@ -27,6 +27,7 @@ import org.springframework.data.repository.core.RepositoryMetadata;
 import org.springframework.data.repository.util.QueryExecutionConverters;
 import org.springframework.data.repository.util.ReactiveWrappers;
 import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.Lazy;
 import org.springframework.data.util.ReflectionUtils;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.util.Assert;
@@ -41,7 +42,7 @@ public abstract class AbstractRepositoryMetadata implements RepositoryMetadata {
 
 	private final TypeInformation<?> typeInformation;
 	private final Class<?> repositoryInterface;
-	private CrudMethods crudMethods;
+	private final Lazy<CrudMethods> crudMethods;
 
 	/**
 	 * Creates a new {@link AbstractRepositoryMetadata}.
@@ -55,6 +56,7 @@ public abstract class AbstractRepositoryMetadata implements RepositoryMetadata {
 
 		this.repositoryInterface = repositoryInterface;
 		this.typeInformation = ClassTypeInformation.from(repositoryInterface);
+		this.crudMethods = Lazy.of(() -> new DefaultCrudMethods(this));
 	}
 
 	/**
@@ -94,12 +96,7 @@ public abstract class AbstractRepositoryMetadata implements RepositoryMetadata {
 	 */
 	@Override
 	public CrudMethods getCrudMethods() {
-
-		if (this.crudMethods == null) {
-			this.crudMethods = new DefaultCrudMethods(this);
-		}
-
-		return this.crudMethods;
+		return this.crudMethods.get();
 	}
 
 	/* 
@@ -109,13 +106,9 @@ public abstract class AbstractRepositoryMetadata implements RepositoryMetadata {
 	@Override
 	public boolean isPagingRepository() {
 
-		Method findAllMethod = getCrudMethods().getFindAllMethod();
-
-		if (findAllMethod == null) {
-			return false;
-		}
-
-		return Arrays.asList(findAllMethod.getParameterTypes()).contains(Pageable.class);
+		return getCrudMethods().getFindAllMethod()//
+				.map(it -> Arrays.asList(it.getParameterTypes()).contains(Pageable.class))//
+				.orElse(false);
 	}
 
 	/* 

src/main/java/org/springframework/data/repository/core/support/DefaultCrudMethods.java

@@ -21,6 +21,7 @@ import static org.springframework.util.ReflectionUtils.*;
 
 import java.io.Serializable;
 import java.lang.reflect.Method;
+import java.util.Optional;
 
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
@@ -48,10 +49,10 @@ public class DefaultCrudMethods implements CrudMethods {
 	private static final String FIND_ALL = "findAll";
 	private static final String DELETE = "delete";
 
-	private final Method findAllMethod;
-	private final Method findOneMethod;
-	private final Method saveMethod;
-	private final Method deleteMethod;
+	private final Optional<Method> findAllMethod;
+	private final Optional<Method> findOneMethod;
+	private final Optional<Method> saveMethod;
+	private final Optional<Method> deleteMethod;
 
 	/**
 	 * Creates a new {@link DefaultCrudMethods} using the given {@link RepositoryMetadata}.
@@ -78,7 +79,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @param metadata must not be {@literal null}.
 	 * @return the most suitable method or {@literal null} if no method could be found.
 	 */
-	private Method selectMostSuitableSaveMethod(RepositoryMetadata metadata) {
+	private Optional<Method> selectMostSuitableSaveMethod(RepositoryMetadata metadata) {
 
 		for (Class<?> type : asList(metadata.getDomainType(), Object.class)) {
 
@@ -89,7 +90,7 @@ public class DefaultCrudMethods implements CrudMethods {
 			}
 		}
 
-		return null;
+		return Optional.empty();
 	}
 
 	/**
@@ -104,7 +105,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @param metadata must not be {@literal null}.
 	 * @return the most suitable method or {@literal null} if no method could be found.
 	 */
-	private Method selectMostSuitableDeleteMethod(RepositoryMetadata metadata) {
+	private Optional<Method> selectMostSuitableDeleteMethod(RepositoryMetadata metadata) {
 
 		for (Class<?> type : asList(metadata.getDomainType(), metadata.getIdType(), Serializable.class, Iterable.class)) {
 
@@ -115,7 +116,7 @@ public class DefaultCrudMethods implements CrudMethods {
 			}
 		}
 
-		return null;
+		return Optional.empty();
 	}
 
 	/**
@@ -129,7 +130,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @param metadata must not be {@literal null}.
 	 * @return the most suitable method or {@literal null} if no method could be found.
 	 */
-	private Method selectMostSuitableFindAllMethod(RepositoryMetadata metadata) {
+	private Optional<Method> selectMostSuitableFindAllMethod(RepositoryMetadata metadata) {
 
 		for (Class<?> type : asList(Pageable.class, Sort.class)) {
 
@@ -147,7 +148,7 @@ public class DefaultCrudMethods implements CrudMethods {
 			return getMostSpecificMethod(findMethod(CrudRepository.class, FIND_ALL), metadata.getRepositoryInterface());
 		}
 
-		return null;
+		return Optional.empty();
 	}
 
 	/**
@@ -160,7 +161,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @param metadata must not be {@literal null}.
 	 * @return the most suitable method or {@literal null} if no method could be found.
 	 */
-	private Method selectMostSuitableFindOneMethod(RepositoryMetadata metadata) {
+	private Optional<Method> selectMostSuitableFindOneMethod(RepositoryMetadata metadata) {
 
 		for (Class<?> type : asList(metadata.getIdType(), Serializable.class)) {
 
@@ -171,7 +172,7 @@ public class DefaultCrudMethods implements CrudMethods {
 			}
 		}
 
-		return null;
+		return Optional.empty();
 	}
 
 	/**
@@ -183,16 +184,12 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @see ClassUtils#getMostSpecificMethod(Method, Class)
 	 * @return
 	 */
-	private static Method getMostSpecificMethod(Method method, Class<?> type) {
+	private static Optional<Method> getMostSpecificMethod(Method method, Class<?> type) {
 
-		Method result = ClassUtils.getMostSpecificMethod(method, type);
-
-		if (result == null) {
-			return null;
-		}
-
-		ReflectionUtils.makeAccessible(result);
-		return result;
+		return Optional.ofNullable(ClassUtils.getMostSpecificMethod(method, type)).map(it -> {
+			ReflectionUtils.makeAccessible(it);
+			return it;
+		});
 	}
 
 	/* 
@@ -200,7 +197,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @see org.springframework.data.repository.core.support.CrudMethods#getSaveMethod()
 	 */
 	@Override
-	public Method getSaveMethod() {
+	public Optional<Method> getSaveMethod() {
 		return saveMethod;
 	}
 
@@ -210,7 +207,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 */
 	@Override
 	public boolean hasSaveMethod() {
-		return saveMethod != null;
+		return saveMethod.isPresent();
 	}
 
 	/* 
@@ -218,7 +215,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @see org.springframework.data.repository.core.support.CrudMethods#getFindAllMethod()
 	 */
 	@Override
-	public Method getFindAllMethod() {
+	public Optional<Method> getFindAllMethod() {
 		return findAllMethod;
 	}
 
@@ -228,7 +225,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 */
 	@Override
 	public boolean hasFindAllMethod() {
-		return findAllMethod != null;
+		return findAllMethod.isPresent();
 	}
 
 	/* 
@@ -236,7 +233,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @see org.springframework.data.repository.core.support.CrudMethods#getFindOneMethod()
 	 */
 	@Override
-	public Method getFindOneMethod() {
+	public Optional<Method> getFindOneMethod() {
 		return findOneMethod;
 	}
 
@@ -246,7 +243,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 */
 	@Override
 	public boolean hasFindOneMethod() {
-		return findOneMethod != null;
+		return findOneMethod.isPresent();
 	}
 
 	/* 
@@ -255,7 +252,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 */
 	@Override
 	public boolean hasDelete() {
-		return this.deleteMethod != null;
+		return this.deleteMethod.isPresent();
 	}
 
 	/* 
@@ -263,7 +260,7 @@ public class DefaultCrudMethods implements CrudMethods {
 	 * @see org.springframework.data.repository.core.support.CrudMethods#getDeleteMethod()
 	 */
 	@Override
-	public Method getDeleteMethod() {
+	public Optional<Method> getDeleteMethod() {
 		return this.deleteMethod;
 	}
 }

src/main/java/org/springframework/data/repository/support/CrudRepositoryInvoker.java

@@ -17,6 +17,7 @@ package org.springframework.data.repository.support;
 
 import java.io.Serializable;
 import java.lang.reflect.Method;
+import java.util.Optional;
 
 import org.springframework.core.convert.ConversionService;
 import org.springframework.data.domain.Pageable;
@@ -114,7 +115,7 @@ class CrudRepositoryInvoker extends ReflectionRepositoryInvoker {
 		}
 	}
 
-	private boolean isRedeclaredMethod(Method method) {
-		return !method.getDeclaringClass().equals(CrudRepository.class);
+	protected boolean isRedeclaredMethod(Optional<Method> method) {
+		return method.map(it -> !it.getDeclaringClass().equals(CrudRepository.class)).orElse(false);
 	}
 }

src/main/java/org/springframework/data/repository/support/ReflectionRepositoryInvoker.java

@@ -113,10 +113,12 @@ class ReflectionRepositoryInvoker implements RepositoryInvoker {
 	 * @see org.springframework.data.rest.core.invoke.RepositoryInvoker#invokeSave(java.lang.Object)
 	 */
 	@Override
+	@SuppressWarnings("unchecked")
 	public <T> T invokeSave(T object) {
 
-		Assert.state(hasSaveMethod(), "Repository doesn't have a save-method declared!");
-		return invoke(methods.getSaveMethod(), object);
+		return methods.getSaveMethod()//
+				.map(it -> (T) invoke(it, object))//
+				.orElseThrow(() -> new IllegalStateException("Repository doesn't have a save-method declared!"));
 	}
 
 	/* 
@@ -133,10 +135,12 @@ class ReflectionRepositoryInvoker implements RepositoryInvoker {
 	 * @see org.springframework.data.rest.core.invoke.RepositoryInvoker#invokeFindOne(java.io.Serializable)
 	 */
 	@Override
+	@SuppressWarnings("unchecked")
 	public <T> T invokeFindOne(Serializable id) {
 
-		Assert.state(hasFindOneMethod(), "Repository doesn't have a find-one-method declared!");
-		return invoke(methods.getFindOneMethod(), convertId(id));
+		return methods.getFindOneMethod()//
+				.map(it -> (T) invoke(it, convertId(id)))//
+				.orElseThrow(() -> new IllegalStateException("Repository doesn't have a find-one-method declared!"));
 	}
 
 	/* 
@@ -156,9 +160,9 @@ class ReflectionRepositoryInvoker implements RepositoryInvoker {
 	public void invokeDelete(Serializable id) {
 
 		Assert.notNull(id, "Identifier must not be null!");
-		Assert.state(hasDeleteMethod(), "Repository doesn't have a delete-method declared!");
 
-		Method method = methods.getDeleteMethod();
+		Method method = methods.getDeleteMethod()
+				.orElseThrow(() -> new IllegalStateException("Repository doesn't have a delete-method declared!"));
 		Class<?> parameterType = method.getParameterTypes()[0];
 		List<Class<? extends Serializable>> idTypes = Arrays.asList(idType, Serializable.class);
 
@@ -260,9 +264,8 @@ class ReflectionRepositoryInvoker implements RepositoryInvoker {
 
 	protected Iterable<Object> invokePagedFindAllReflectively(Pageable pageable) {
 
-		Assert.state(hasFindAllMethod(), "Repository doesn't have a find-all-method declared!");
-
-		Method method = methods.getFindAllMethod();
+		Method method = methods.getFindAllMethod()
+				.orElseThrow(() -> new IllegalStateException("Repository doesn't have a find-all-method declared!"));
 		Class<?>[] types = method.getParameterTypes();
 
 		if (types.length == 0) {
@@ -278,9 +281,8 @@ class ReflectionRepositoryInvoker implements RepositoryInvoker {
 
 	protected Iterable<Object> invokeSortedFindAllReflectively(Sort sort) {
 
-		Assert.state(hasFindAllMethod(), "Repository doesn't have a find-all-method declared!");
-
-		Method method = methods.getFindAllMethod();
+		Method method = methods.getFindAllMethod()
+				.orElseThrow(() -> new IllegalStateException("Repository doesn't have a find-all-method declared!"));
 		Class<?>[] types = method.getParameterTypes();
 
 		if (types.length == 0) {

src/test/java/org/springframework/data/repository/core/support/DefaultCrudMethodsUnitTests.java

@@ -19,6 +19,7 @@ import static org.assertj.core.api.Assertions.*;
 
 import java.io.Serializable;
 import java.lang.reflect.Method;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 
@@ -92,7 +93,7 @@ public class DefaultCrudMethodsUnitTests {
 	public void doesNotDetectInvalidlyDeclaredMethods() throws Exception {
 
 		Class<RepositoryWithInvalidPagingFindAll> type = RepositoryWithInvalidPagingFindAll.class;
-		assertFindAllMethodOn(type, null);
+		assertFindAllMethodOn(type, Optional.empty());
 	}
 
 	@Test // DATACMNS-393
@@ -132,10 +133,14 @@ public class DefaultCrudMethodsUnitTests {
 
 		CrudMethods methods = getMethodsFor(RepositoryWithAllCrudMethodOverloaded.class);
 
-		assertThat(methods.getSaveMethod().isAccessible()).isTrue();
-		assertThat(methods.getDeleteMethod().isAccessible()).isTrue();
-		assertThat(methods.getFindAllMethod().isAccessible()).isTrue();
-		assertThat(methods.getFindOneMethod().isAccessible()).isTrue();
+		Arrays
+				.asList(methods.getSaveMethod(), methods.getDeleteMethod(), methods.getFindAllMethod(),
+						methods.getFindOneMethod())//
+				.forEach(method -> {
+					assertThat(method).hasValueSatisfying(it -> {
+						assertThat(it.isAccessible()).isTrue();
+					});
+				});
 	}
 
 	private static CrudMethods getMethodsFor(Class<?> repositoryInterface) {
@@ -148,10 +153,14 @@ public class DefaultCrudMethodsUnitTests {
 	}
 
 	private static void assertFindAllMethodOn(Class<?> type, Method method) {
+		assertFindAllMethodOn(type, Optional.ofNullable(method));
+	}
+
+	private static void assertFindAllMethodOn(Class<?> type, Optional<Method> method) {
 
 		CrudMethods methods = getMethodsFor(type);
 
-		assertThat(methods.hasFindAllMethod()).isEqualTo(method != null);
+		assertThat(methods.hasFindAllMethod()).isEqualTo(method.isPresent());
 		assertThat(methods.getFindAllMethod()).isEqualTo(method);
 	}
 
@@ -160,7 +169,7 @@ public class DefaultCrudMethodsUnitTests {
 		CrudMethods methods = getMethodsFor(type);
 
 		assertThat(methods.hasFindOneMethod()).isEqualTo(method != null);
-		assertThat(methods.getFindOneMethod()).isEqualTo(method);
+		assertThat(methods.getFindOneMethod()).hasValue(method);
 	}
 
 	private static void assertDeleteMethodOn(Class<?> type, Method method) {
@@ -168,7 +177,7 @@ public class DefaultCrudMethodsUnitTests {
 		CrudMethods methods = getMethodsFor(type);
 
 		assertThat(methods.hasDelete()).isEqualTo(method != null);
-		assertThat(methods.getDeleteMethod()).isEqualTo(method);
+		assertThat(methods.getDeleteMethod()).hasValue(method);
 	}
 
 	private static void assertSaveMethodOn(Class<?> type, Method method) {
@@ -176,7 +185,7 @@ public class DefaultCrudMethodsUnitTests {
 		CrudMethods methods = getMethodsFor(type);
 
 		assertThat(methods.hasSaveMethod()).isEqualTo(method != null);
-		assertThat(methods.getSaveMethod()).isEqualTo(method);
+		assertThat(methods.getSaveMethod()).hasValue(method);
 	}
 
 	private static void assertSaveMethodPresent(Class<?> type, boolean present) {
@@ -184,7 +193,7 @@ public class DefaultCrudMethodsUnitTests {
 		CrudMethods methods = getMethodsFor(type);
 
 		assertThat(methods.hasSaveMethod()).isEqualTo(present);
-		assertThat(methods.getSaveMethod()).matches(method -> present ? method != null : method == null);
+		assertThat(methods.getSaveMethod().isPresent()).isEqualTo(present);
 	}
 
 	interface Domain {}