Improve error message if store module doesn't support a well-known fragment interface

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-commons</artifactId>
-	<version>2.5.0-SNAPSHOT</version>
+	<version>2.5.0-GH-2341-SNAPSHOT</version>
 
 	<name>Spring Data Core</name>
 
@@ -339,7 +339,7 @@
 			<version>0.1.4</version>
 			<scope>test</scope>
 		</dependency>
-		
+
 		<dependency>
 			<groupId>org.jmolecules.integrations</groupId>
 			<artifactId>jmolecules-spring</artifactId>

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

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.repository.core;
+
+import org.springframework.dao.InvalidDataAccessApiUsageException;
+
+/**
+ * Exception thrown in the context of repository creation.
+ *
+ * @author Mark Paluch
+ * @since 2.5
+ */
+@SuppressWarnings("serial")
+public class RepositoryCreationException extends InvalidDataAccessApiUsageException {
+
+	private final Class<?> repositoryInterface;
+
+	/**
+	 * Constructor for RepositoryCreationException.
+	 *
+	 * @param msg the detail message.
+	 * @param repositoryInterface the repository interface.
+	 */
+	public RepositoryCreationException(String msg, Class<?> repositoryInterface) {
+		super(msg);
+		this.repositoryInterface = repositoryInterface;
+	}
+
+	/**
+	 * Constructor for RepositoryException.
+	 *
+	 * @param msg the detail message.
+	 * @param cause the root cause from the data access API in use.
+	 * @param repositoryInterface the repository interface.
+	 */
+	public RepositoryCreationException(String msg, Throwable cause, Class<?> repositoryInterface) {
+		super(msg, cause);
+		this.repositoryInterface = repositoryInterface;
+	}
+
+	public Class<?> getRepositoryInterface() {
+		return repositoryInterface;
+	}
+}

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

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.repository.core.support;
+
+import org.springframework.data.repository.core.RepositoryCreationException;
+
+/**
+ * Exception thrown during repository creation or repository method invocation when invoking a repository method on a
+ * fragment without an implementation.
+ *
+ * @author Mark Paluch
+ * @since 2.5
+ */
+@SuppressWarnings("serial")
+public class FragmentNotImplementedException extends RepositoryCreationException {
+
+	private final RepositoryFragment<?> fragment;
+
+	/**
+	 * Constructor for FragmentNotImplementedException.
+	 *
+	 * @param msg the detail message.
+	 * @param repositoryInterface the repository interface.
+	 * @param fragment the offending repository fragment.
+	 */
+	public FragmentNotImplementedException(String msg, Class<?> repositoryInterface, RepositoryFragment<?> fragment) {
+		super(msg, repositoryInterface);
+		this.fragment = fragment;
+	}
+
+	public RepositoryFragment<?> getFragment() {
+		return fragment;
+	}
+}

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.repository.core.support;
+
+import org.springframework.data.repository.core.RepositoryCreationException;
+
+/**
+ * Exception thrown during repository creation when a the repository has custom methods that are not backed by a
+ * fragment or if no fragment could be found for a repository method invocation.
+ *
+ * @author Mark Paluch
+ * @since 2.5
+ */
+@SuppressWarnings("serial")
+public class IncompleteRepositoryCompositionException extends RepositoryCreationException {
+
+	/**
+	 * Constructor for IncompleteRepositoryCompositionException.
+	 *
+	 * @param msg the detail message.
+	 * @param repositoryInterface the repository interface.
+	 */
+	public IncompleteRepositoryCompositionException(String msg, Class<?> repositoryInterface) {
+		super(msg, repositoryInterface);
+	}
+}

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

@@ -29,6 +29,7 @@
 import org.springframework.data.repository.core.RepositoryInformation;
 import org.springframework.data.repository.core.support.RepositoryInvocationMulticaster.DefaultRepositoryInvocationMulticaster;
 import org.springframework.data.repository.core.support.RepositoryInvocationMulticaster.NoOpRepositoryInvocationMulticaster;
+import org.springframework.data.repository.query.QueryCreationException;
 import org.springframework.data.repository.query.QueryLookupStrategy;
 import org.springframework.data.repository.query.QueryMethod;
 import org.springframework.data.repository.query.RepositoryQuery;
@@ -97,7 +98,13 @@ private Map<Method, RepositoryQuery> mapMethodsToQuery(RepositoryInformation rep
 
 	private Pair<Method, RepositoryQuery> lookupQuery(Method method, RepositoryInformation information,
 			QueryLookupStrategy strategy, ProjectionFactory projectionFactory) {
-		return Pair.of(method, strategy.resolveQuery(method, information, projectionFactory, namedQueries));
+		try {
+			return Pair.of(method, strategy.resolveQuery(method, information, projectionFactory, namedQueries));
+		} catch (QueryCreationException e) {
+			throw e;
+		} catch (RuntimeException e) {
+			throw QueryCreationException.create(e.getMessage(), e, information.getRepositoryInterface(), method);
+		}
 	}
 
 	@SuppressWarnings({ "rawtypes", "unchecked" })

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

@@ -316,8 +316,12 @@ Method getMethod(Method method) {
 	public void validateImplementation() {
 
 		fragments.stream().forEach(it -> it.getImplementation() //
-				.orElseThrow(() -> new IllegalStateException(String.format("Fragment %s has no implementation.",
-						ClassUtils.getQualifiedName(it.getSignatureContributor())))));
+				.orElseThrow(() -> {
+					Class<?> repositoryInterface = metadata != null ? metadata.getRepositoryInterface() : Object.class;
+					return new FragmentNotImplementedException(String.format("Fragment %s used in %s has no implementation.",
+							ClassUtils.getQualifiedName(it.getSignatureContributor()),
+							ClassUtils.getQualifiedName(repositoryInterface)), repositoryInterface, it);
+				}));
 	}
 
 	/*

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

@@ -19,6 +19,7 @@
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -28,6 +29,7 @@
 import org.aopalliance.intercept.MethodInvocation;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.aop.framework.ProxyFactory;
 import org.springframework.aop.interceptor.ExposeInvocationInterceptor;
 import org.springframework.beans.BeanUtils;
@@ -57,12 +59,12 @@
 import org.springframework.data.repository.query.QueryMethod;
 import org.springframework.data.repository.query.QueryMethodEvaluationContextProvider;
 import org.springframework.data.repository.query.RepositoryQuery;
-import org.springframework.data.repository.util.ClassUtils;
 import org.springframework.data.repository.util.QueryExecutionConverters;
 import org.springframework.data.util.ReflectionUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.transaction.interceptor.TransactionalProxy;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.ConcurrentReferenceHashMap.ReferenceType;
 import org.springframework.util.ObjectUtils;
@@ -312,15 +314,16 @@ public <T> T getRepository(Class<T> repositoryInterface, RepositoryFragments fra
 
 		repositoryCompositionStep.end();
 
-		validate(information, composition);
-
 		StartupStep repositoryTargetStep = onEvent(applicationStartup, "spring.data.repository.target",
 				repositoryInterface);
 		Object target = getTargetRepository(information);
 
 		repositoryTargetStep.tag("target", target.getClass().getName());
 		repositoryTargetStep.end();
 
+		RepositoryComposition compositionToUse = composition.append(RepositoryFragment.implemented(target));
+		validate(information, compositionToUse);
+
 		// Create proxy
 		StartupStep repositoryProxyStep = onEvent(applicationStartup, "spring.data.repository.proxy", repositoryInterface);
 		ProxyFactory result = new ProxyFactory();
@@ -357,7 +360,6 @@ public <T> T getRepository(Class<T> repositoryInterface, RepositoryFragments fra
 		result.addAdvice(new QueryExecutorMethodInterceptor(information, projectionFactory, queryLookupStrategy,
 				namedQueries, queryPostProcessors, methodInvocationListeners));
 
-		RepositoryComposition compositionToUse = composition.append(RepositoryFragment.implemented(target));
 		result.addAdvice(
 				new ImplementationMethodExecutionInterceptor(information, compositionToUse, methodInvocationListeners));
 
@@ -502,17 +504,7 @@ protected Optional<QueryLookupStrategy> getQueryLookupStrategy(@Nullable Key key
 	 */
 	private void validate(RepositoryInformation repositoryInformation, RepositoryComposition composition) {
 
-		if (repositoryInformation.hasCustomMethod()) {
-
-			if (composition.isEmpty()) {
-
-				throw new IllegalArgumentException(
-						String.format("You have custom methods in %s but have not provided a custom implementation!",
-								repositoryInformation.getRepositoryInterface()));
-			}
-
-			composition.validateImplementation();
-		}
+		RepositoryValidator.validate(composition, getClass(), repositoryInformation);
 
 		validate(repositoryInformation);
 	}
@@ -606,7 +598,7 @@ public Object invoke(@SuppressWarnings("null") MethodInvocation invocation) thro
 			try {
 				return composition.invoke(invocationMulticaster, method, arguments);
 			} catch (Exception e) {
-				ClassUtils.unwrapReflectionException(e);
+				org.springframework.util.ReflectionUtils.handleReflectionException(e);
 			}
 
 			throw new IllegalStateException("Should not occur!");
@@ -715,4 +707,94 @@ public String toString() {
 					+ this.getRepositoryInterfaceName() + ", compositionHash=" + this.getCompositionHash() + ")";
 		}
 	}
+
+	/**
+	 * Validator utility to catch common mismatches with a proper error message instead of letting the query mechanism
+	 * attempt implementing a query method and fail with a less specific message.
+	 */
+	static class RepositoryValidator {
+
+		static Map<Class<?>, String> WELL_KNOWN_EXECUTORS = new HashMap<>();
+
+		static {
+
+			org.springframework.data.repository.util.ClassUtils.ifPresent(
+					"org.springframework.data.querydsl.QuerydslPredicateExecutor", RepositoryValidator.class.getClassLoader(),
+					it -> {
+						WELL_KNOWN_EXECUTORS.put(it, "Querydsl");
+					});
+
+			org.springframework.data.repository.util.ClassUtils.ifPresent(
+					"org.springframework.data.querydsl.ReactiveQuerydslPredicateExecutor",
+					RepositoryValidator.class.getClassLoader(), it -> {
+						WELL_KNOWN_EXECUTORS.put(it, "Reactive Querydsl");
+					});
+
+			org.springframework.data.repository.util.ClassUtils.ifPresent(
+					"org.springframework.data.repository.query.QueryByExampleExecutor",
+					RepositoryValidator.class.getClassLoader(), it -> {
+						WELL_KNOWN_EXECUTORS.put(it, "Query by Example");
+					});
+
+			org.springframework.data.repository.util.ClassUtils.ifPresent(
+					"org.springframework.data.repository.query.ReactiveQueryByExampleExecutor",
+					RepositoryValidator.class.getClassLoader(), it -> {
+						WELL_KNOWN_EXECUTORS.put(it, "Reactive Query by Example");
+					});
+		}
+
+		/**
+		 * Validate the {@link RepositoryComposition} for custom implementations and well-known executors.
+		 *
+		 * @param composition
+		 * @param source
+		 * @param repositoryInformation
+		 */
+		public static void validate(RepositoryComposition composition, Class<?> source,
+				RepositoryInformation repositoryInformation) {
+
+			Class<?> repositoryInterface = repositoryInformation.getRepositoryInterface();
+			if (repositoryInformation.hasCustomMethod()) {
+
+				if (composition.isEmpty()) {
+
+					throw new IncompleteRepositoryCompositionException(
+							String.format("You have custom methods in %s but have not provided a custom implementation!",
+									org.springframework.util.ClassUtils.getQualifiedName(repositoryInterface)),
+							repositoryInterface);
+				}
+
+				composition.validateImplementation();
+			}
+
+			for (Map.Entry<Class<?>, String> entry : WELL_KNOWN_EXECUTORS.entrySet()) {
+
+				Class<?> executorInterface = entry.getKey();
+				if (!executorInterface.isAssignableFrom(repositoryInterface)) {
+					continue;
+				}
+
+				if (!containsFragmentImplementation(composition, executorInterface)) {
+					throw new UnsupportedFragmentException(
+							String.format("Repository %s implements %s but %s does not support %s!",
+									ClassUtils.getQualifiedName(repositoryInterface), ClassUtils.getQualifiedName(executorInterface),
+									ClassUtils.getShortName(source), entry.getValue()),
+							repositoryInterface, executorInterface);
+				}
+			}
+		}
+
+		private static boolean containsFragmentImplementation(RepositoryComposition composition,
+				Class<?> executorInterface) {
+
+			for (RepositoryFragment<?> fragment : composition.getFragments()) {
+
+				if (fragment.getImplementation().filter(executorInterface::isInstance).isPresent()) {
+					return true;
+				}
+			}
+
+			return false;
+		}
+	}
 }