Detect ReadPreference for annotated aggregations and inherited find methods.

This commit reduces the API surface of the ReadPreference annotation leaving fine grained control such as Tags to the Template API.
Next to supporting read preference for annotated queries we now also make sure to apply read preferences for annotated aggregation methods as well as predefined finder methods running queries.

See: #2971
Original Pull Request: #4503

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/Aggregation.java

@@ -44,6 +44,7 @@
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Documented
 @QueryAnnotation
+@ReadPreference
 public @interface Aggregation {
 
 	/**
@@ -127,4 +128,21 @@
 	 */
 	@AliasFor(annotation = Collation.class, attribute = "value")
 	String collation() default "";
+
+	/**
+	 * The mode of the read preference to use. <br />
+	 * {@code @Aggregation(pipeline = { ... }, readPreference = "secondary")} can be used as shortcut for:
+	 *
+	 * <pre class="code">
+	 * &#64;@Aggregation(pipeline = { ... })
+	 * &#64;ReadPreference("secondary")
+	 * List&lt;PersonAggregate&gt; groupByLastnameAnd(String property);
+	 * </pre>
+	 *
+	 * @return the index name.
+	 * @since 4.2
+	 * @see ReadPreference#value()
+	 */
+	@AliasFor(annotation = ReadPreference.class, attribute = "value")
+	String readPreference() default "";
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/Query.java

@@ -157,7 +157,7 @@
 	 * <pre class="code">
 	 * &#64;Query(...)
 	 * &#64;ReadPreference("secondary")
-	 * List&lt;User&gt; findAllByLastname(String collation);
+	 * List&lt;User&gt; findAllByLastname(String lastname);
 	 * </pre>
 	 *
 	 * @return the index name.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/ReadPreference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2023 the original author or authors.
+ * Copyright 2023 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.
@@ -25,6 +25,7 @@
  * Annotation to declare read preference for repository and query.
  *
  * @author Jorge Rodríguez
+ * @author Christoph Strobl
  * @since 4.2
  */
 @Retention(RetentionPolicy.RUNTIME)
@@ -38,16 +39,5 @@
 	 */
 	String value() default "";
 
-	/**
-	 * Set read preference tags
-	 * @return read preference tags
-	 */
-	ReadPreferenceTag[] tags() default {};
-
-	/**
-	 * Set read preference maxStalenessSeconds
-	 * @return read preference maxStalenessSeconds
-	 */
-	long maxStalenessSeconds() default -1;
 }
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/ReadPreferenceTag.java

@@ -159,8 +159,8 @@ private Query applyAnnotatedReadPreferenceIfPresent(Query query) {
 		if (!method.hasAnnotatedReadPreference()) {
 			return query;
 		}
-		
-		return query.withReadPreference(method.getAnnotatedReadPreference());
+
+		return query.withReadPreference(com.mongodb.ReadPreference.valueOf(method.getAnnotatedReadPreference()));
 	}
 
 	private MongoQueryExecution getExecution(ConvertingParameterAccessor accessor, FindWithQuery<?> operation) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AbstractMongoQuery.java

@@ -164,7 +164,6 @@ protected Publisher<Object> doExecute(ReactiveMongoQueryMethod method, ResultPro
 			query = applyHintIfPresent(query);
 			query = applyAnnotatedReadPreferenceIfPresent(query);
 
-
 			FindWithQuery<?> find = typeToRead == null //
 					? findOperationWithProjection //
 					: findOperationWithProjection.as(typeToRead);
@@ -303,7 +302,7 @@ private Query applyAnnotatedReadPreferenceIfPresent(Query query) {
 			return query;
 		}
 
-		return query.withReadPreference(method.getAnnotatedReadPreference());
+		return query.withReadPreference(com.mongodb.ReadPreference.valueOf(method.getAnnotatedReadPreference()));
 	}
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AbstractReactiveMongoQuery.java

@@ -37,6 +37,8 @@
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 
+import com.mongodb.ReadPreference;
+
 /**
  * Internal utility class to help avoid duplicate code required in both the reactive and the sync {@link Aggregation}
  * support offered by repositories.
@@ -117,6 +119,22 @@ static AggregationOptions.Builder applyHint(AggregationOptions.Builder builder,
 		return builder.hint(queryMethod.getAnnotatedHint());
 	}
 
+	/**
+	 * If present apply the preference from the {@link org.springframework.data.mongodb.repository.ReadPreference} annotation.
+	 *
+	 * @param builder must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 4.2
+	 */
+	static AggregationOptions.Builder applyReadPreference(AggregationOptions.Builder builder, MongoQueryMethod queryMethod) {
+
+		if (!queryMethod.hasAnnotatedReadPreference()) {
+			return builder;
+		}
+
+		return builder.readPreference(ReadPreference.valueOf(queryMethod.getAnnotatedReadPreference()));
+	}
+
 	/**
 	 * Append {@code $sort} aggregation stage if {@link ConvertingParameterAccessor#getSort()} is present.
 	 *

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AggregationUtils.java

@@ -22,11 +22,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.concurrent.TimeUnit;
-import java.util.stream.Collectors;
 
-import com.mongodb.Tag;
-import com.mongodb.TagSet;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.data.geo.GeoPage;
 import org.springframework.data.geo.GeoResult;
@@ -322,7 +318,7 @@ public String getAnnotatedSort() {
 
 
 	/**
-	 * Check if the query method is decorated with an non empty {@link Query#collation()}.
+	 * Check if the query method is decorated with an non empty {@link ReadPreference}.
 	 *
 	 * @return true if method annotated with {@link Query} or {@link Aggregation} having a non-empty collation attribute.
 	 * @since 4.2
@@ -334,44 +330,27 @@ public boolean hasAnnotatedReadPreference() {
 	/**
 	 * Get the {@link com.mongodb.ReadPreference} extracted from the {@link ReadPreference} annotation.
 	 *
-	 * @return the {@link ReadPreference()}.
+	 * @return the name of the {@link ReadPreference()}.
 	 * @throws IllegalStateException if method not annotated with {@link Query}. Make sure to check
 	 *                               {@link #hasAnnotatedQuery()} first.
 	 * @since 4.2
 	 */
-	public com.mongodb.ReadPreference getAnnotatedReadPreference() {
+	public String getAnnotatedReadPreference() {
 
-		return doFindReadPreferenceAnnotation().map(annotationReadPreference -> {
-
-			com.mongodb.ReadPreference readPreference = com.mongodb.ReadPreference.valueOf(annotationReadPreference.value());
-
-			if (annotationReadPreference.tags().length > 0) {
-				List<Tag> tags = Arrays.stream(annotationReadPreference.tags())
-						.map(tag -> new Tag(tag.name(), tag.value()))
-						.collect(Collectors.toList());
-				readPreference = readPreference.withTagSet(new TagSet(tags));
-			}
-			
-			if (annotationReadPreference.maxStalenessSeconds() > 0) {
-				readPreference = readPreference.withMaxStalenessMS(annotationReadPreference.maxStalenessSeconds(), TimeUnit.SECONDS);
-			}
-			
-			return readPreference;
-		}).orElseThrow(() -> new IllegalStateException(
+		return doFindReadPreferenceAnnotation().map(ReadPreference::value).orElseThrow(() -> new IllegalStateException(
 						"Expected to find @ReadPreference annotation but did not; Make sure to check hasAnnotatedReadPreference() before."));
 	}
 
 	/**
-	 * Get {@link com.mongodb.ReadPreference} from query. First check if the method is annotated. If not, check if the class is annotated.
+	 * Get {@link com.mongodb.ReadPreference#getName() name} from query. First check if the method is annotated. If not, check if the class is annotated.
 	 * So if the method and the class are annotated with @ReadPreference, the method annotation takes precedence.
-	 * @return the {@link com.mongodb.ReadPreference}
+	 * @return the {@link ReadPreference}
 	 * @since 4.2
 	 */
 	private Optional<ReadPreference> doFindReadPreferenceAnnotation() {
 		return doFindAnnotation(ReadPreference.class).or(() -> doFindAnnotationInClass(ReadPreference.class));
 	}
 
-
 	/**
 	 * Check if the query method is decorated with an non empty {@link Query#collation()} or or
 	 * {@link Aggregation#collation()}.
@@ -458,7 +437,6 @@ Optional<Update> lookupUpdateAnnotation() {
 
 	@SuppressWarnings("unchecked")
 	private <A extends Annotation> Optional<A> doFindAnnotation(Class<A> annotationType) {
-		
 
 		return (Optional<A>) this.annotationCache.computeIfAbsent(annotationType,
 				it -> Optional.ofNullable(AnnotatedElementUtils.findMergedAnnotation(method, it)));

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/MongoQueryMethod.java

@@ -132,6 +132,7 @@ private AggregationOptions computeOptions(MongoQueryMethod method, ConvertingPar
 				expressionParser, evaluationContextProvider);
 		AggregationUtils.applyMeta(builder, method);
 		AggregationUtils.applyHint(builder, method);
+		AggregationUtils.applyReadPreference(builder, method);
 
 		TypeInformation<?> returnType = method.getReturnType();
 		if (returnType.getComponentType() != null) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/ReactiveStringBasedAggregation.java

@@ -181,6 +181,7 @@ private AggregationOptions computeOptions(MongoQueryMethod method, ConvertingPar
 				expressionParser, evaluationContextProvider);
 		AggregationUtils.applyMeta(builder, method);
 		AggregationUtils.applyHint(builder, method);
+		AggregationUtils.applyReadPreference(builder, method);
 
 		if (ReflectionUtils.isVoid(method.getReturnType().getType()) && pipeline.isOutOrMerge()) {
 			builder.skipOutput();