Switch `Meta.allowDiskUse` from `boolean` to `String`.

Closes: #4667
Original pull request: #5035

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOptions.java

@@ -23,6 +23,7 @@ import org.jspecify.annotations.Nullable;
 import org.springframework.data.mongodb.core.ReadConcernAware;
 import org.springframework.data.mongodb.core.ReadPreferenceAware;
 import org.springframework.data.mongodb.core.query.Collation;
+import org.springframework.data.mongodb.core.query.DiskUse;
 import org.springframework.data.mongodb.util.BsonUtils;
 import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
@@ -60,7 +61,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	private static final String MAX_TIME = "maxTimeMS";
 	private static final String HINT = "hint";
 
-	private final Optional<Boolean> allowDiskUse;
+	private final DiskUse diskUse;
 	private final boolean explain;
 	private final Optional<Document> cursor;
 	private final Optional<Collation> collation;
@@ -85,6 +86,15 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 		this(allowDiskUse, explain, cursor, null);
 	}
 
+	public AggregationOptions(DiskUse diskUse, boolean explain, @Nullable Document cursor) {
+		this(diskUse, explain, cursor, null);
+	}
+
+	public AggregationOptions(DiskUse allowDiskUse, boolean explain, @Nullable Document cursor,
+		@Nullable Collation collation) {
+		this(allowDiskUse, explain, cursor, collation, null);
+	}
+
 	/**
 	 * Creates a new {@link AggregationOptions}.
 	 *
@@ -97,7 +107,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	 */
 	public AggregationOptions(boolean allowDiskUse, boolean explain, @Nullable Document cursor,
 			@Nullable Collation collation) {
-		this(allowDiskUse, explain, cursor, collation, null, null);
+		this(DiskUse.of(allowDiskUse), explain, cursor, collation, null, null);
 	}
 
 	/**
@@ -113,13 +123,18 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	 */
 	public AggregationOptions(boolean allowDiskUse, boolean explain, @Nullable Document cursor,
 			@Nullable Collation collation, @Nullable String comment) {
+		this(allowDiskUse ? DiskUse.ALLOW : DiskUse.DENY, explain, cursor, collation, comment, null);
+	}
+
+	public AggregationOptions(DiskUse allowDiskUse, boolean explain, @Nullable Document cursor,
+		@Nullable Collation collation, @Nullable String comment) {
 		this(allowDiskUse, explain, cursor, collation, comment, null);
 	}
 
 	/**
 	 * Creates a new {@link AggregationOptions}.
 	 *
-	 * @param allowDiskUse whether to off-load intensive sort-operations to disk.
+	 * @param diskUse whether to off-load intensive sort-operations to disk.
 	 * @param explain whether to get the execution plan for the aggregation instead of the actual results.
 	 * @param cursor can be {@literal null}, used to pass additional options (such as {@code batchSize}) to the
 	 *          aggregation.
@@ -128,10 +143,10 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	 * @param hint can be {@literal null}, used to provide an index that would be forcibly used by query optimizer.
 	 * @since 3.1
 	 */
-	private AggregationOptions(@Nullable Boolean allowDiskUse, boolean explain, @Nullable Document cursor,
+	private AggregationOptions(DiskUse diskUse, boolean explain, @Nullable Document cursor,
 			@Nullable Collation collation, @Nullable String comment, @Nullable Object hint) {
 
-		this.allowDiskUse = Optional.ofNullable(allowDiskUse);
+		this.diskUse = diskUse;
 		this.explain = explain;
 		this.cursor = Optional.ofNullable(cursor);
 		this.collation = Optional.ofNullable(collation);
@@ -172,7 +187,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 		String comment = document.getString(COMMENT);
 		Document hint = document.get(HINT, Document.class);
 
-		AggregationOptions options = new AggregationOptions(allowDiskUse, explain, cursor, collation, comment, hint);
+		AggregationOptions options = new AggregationOptions(DiskUse.of(allowDiskUse) , explain, cursor, collation, comment, hint);
 		if (document.containsKey(MAX_TIME)) {
 			options.maxTime = Duration.ofMillis(document.getLong(MAX_TIME));
 		}
@@ -196,7 +211,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	 * @return {@literal true} if enabled; {@literal false} otherwise (or if not set).
 	 */
 	public boolean isAllowDiskUse() {
-		return allowDiskUse.orElse(false);
+		return diskUse.equals(DiskUse.ALLOW);
 	}
 
 	/**
@@ -206,7 +221,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	 * @since 4.2.5
 	 */
 	public boolean isAllowDiskUseSet() {
-		return allowDiskUse.isPresent();
+		return !diskUse.equals(DiskUse.DEFAULT);
 	}
 
 	/**
@@ -427,7 +442,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 	 */
 	public static class Builder {
 
-		private @Nullable Boolean allowDiskUse;
+		private @Nullable DiskUse diskUse = DiskUse.DEFAULT;
 		private boolean explain;
 		private @Nullable Document cursor;
 		private @Nullable Collation collation;
@@ -447,8 +462,19 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 		 */
 		@Contract("_ -> this")
 		public Builder allowDiskUse(boolean allowDiskUse) {
+			return diskUse(DiskUse.of(allowDiskUse));
+		}
+
+		/**
+		 * Defines whether to off-load intensive sort-operations to disk.
+		 *
+		 * @param diskUse use {@literal true} to allow disk use during the aggregation.
+		 * @return this.
+		 */
+		@Contract("_ -> this")
+		public Builder diskUse(DiskUse diskUse) {
 
-			this.allowDiskUse = allowDiskUse;
+			this.diskUse = diskUse;
 			return this;
 		}
 
@@ -655,7 +681,7 @@ public class AggregationOptions implements ReadConcernAware, ReadPreferenceAware
 		@Contract("-> new")
 		public AggregationOptions build() {
 
-			AggregationOptions options = new AggregationOptions(allowDiskUse, explain, cursor, collation, comment, hint);
+			AggregationOptions options = new AggregationOptions(diskUse, explain, cursor, collation, comment, hint);
 			if (maxTime != null) {
 				options.maxTime = maxTime;
 			}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/DiskUse.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2025-present 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.mongodb.core.query;
+
+import org.jspecify.annotations.Nullable;
+import org.springframework.util.StringUtils;
+
+/**
+ * Disk use indicates if the MongoDB server is allowed to write temporary files to disk during query/aggregation
+ * execution. MongoDB 6.0 server (and later) default for {@literal allowDiskUseByDefault} is {@literal true} on server
+ * side.
+ *
+ * @author Christoph Strobl
+ * @since 5.0
+ */
+public enum DiskUse {
+
+	/**
+	 * Go with the server default value and do not specify any override.
+	 */
+	DEFAULT,
+
+	/**
+	 * Override server default value and explicitly allow disk writes.
+	 */
+	ALLOW,
+
+	/**
+	 * Override server default value and explicitly deny disk writes.
+	 */
+	DENY;
+
+	/**
+	 * Obtain the {@link DiskUse} corresponding to the given Boolean flag. {@literal null} is considered {@link #DEFAULT},
+	 * {@literal true} as {@link #ALLOW}, {@literal false} as {@link #DENY}.
+	 *
+	 * @param value can be {@literal null}.
+	 * @return the {@link DiskUse} corresponding to the given value.
+	 */
+	public static DiskUse of(@Nullable Boolean value) {
+		return value != null ? (value ? ALLOW : DENY) : DEFAULT;
+	}
+
+	/**
+	 * Obtain the {@link DiskUse} referred to by the given value. Considers {@literal null} or empty Strings as
+	 * {@link #DEFAULT}, {@literal true} as {@link #ALLOW}, {@literal false} as {@link #DENY} and delegates other values
+	 * to {@link #valueOf(String)}.
+	 *
+	 * @param value can be {@literal null}.
+	 * @return the {@link DiskUse} corresponding to the given value.
+	 * @throws IllegalArgumentException if not matching {@link DiskUse} found.
+	 */
+	public static DiskUse of(@Nullable String value) {
+
+		if (!StringUtils.hasText(value)) {
+			return DEFAULT;
+		}
+
+		return switch (value) {
+			case "true" -> ALLOW;
+			case "false" -> DENY;
+			default -> valueOf(value.toUpperCase());
+		};
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Meta.java

@@ -51,7 +51,7 @@ public class Meta {
 	private Map<String, Object> values = Collections.emptyMap();
 	private Set<CursorOption> flags = Collections.emptySet();
 	private @Nullable Integer cursorBatchSize;
-	private @Nullable Boolean allowDiskUse;
+	private DiskUse diskUse = DiskUse.DEFAULT;
 
 	public Meta() {}
 
@@ -66,7 +66,7 @@ public class Meta {
 		this.values = new LinkedHashMap<>(source.values);
 		this.flags = new LinkedHashSet<>(source.flags);
 		this.cursorBatchSize = source.cursorBatchSize;
-		this.allowDiskUse = source.allowDiskUse;
+		this.diskUse = source.diskUse;
 	}
 
 	/**
@@ -230,7 +230,7 @@ public class Meta {
 	 */
 	@Nullable
 	public Boolean getAllowDiskUse() {
-		return allowDiskUse;
+		return diskUse.equals(DiskUse.DEFAULT) ? null : diskUse.equals(DiskUse.ALLOW);
 	}
 
 	/**
@@ -244,14 +244,18 @@ public class Meta {
 	 * @since 3.0
 	 */
 	public void setAllowDiskUse(@Nullable Boolean allowDiskUse) {
-		this.allowDiskUse = allowDiskUse;
+		setDiskUse(DiskUse.of(allowDiskUse));
+	}
+
+	public void setDiskUse(DiskUse diskUse) {
+		this.diskUse = diskUse;
 	}
 
 	/**
 	 * @return
 	 */
 	public boolean hasValues() {
-		return !this.values.isEmpty() || !this.flags.isEmpty() || this.cursorBatchSize != null || this.allowDiskUse != null;
+		return !this.values.isEmpty() || !this.flags.isEmpty() || this.cursorBatchSize != null || !this.diskUse.equals(DiskUse.DEFAULT);
 	}
 
 	/**

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

@@ -582,8 +582,13 @@ public class Query implements ReadConcernAware, ReadPreferenceAware {
 	 */
 	@Contract("_ -> this")
 	public Query allowDiskUse(boolean allowDiskUse) {
+		return diskUse(DiskUse.of(allowDiskUse));
+	}
+
+	@Contract("_ -> this")
+	public Query diskUse(DiskUse diskUse) {
 
-		meta.setAllowDiskUse(allowDiskUse);
+		meta.setDiskUse(diskUse);
 		return this;
 	}
 

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

@@ -69,11 +69,17 @@ public @interface Meta {
 
 	/**
 	 * When set to {@literal true}, aggregation stages can write data to disk.
+	 * Valid arguments are:
+	 * <dl>
+	 *     <dt>""</dt><dd>DiskUse#DEFAULT</dd>
+	 *     <dt>true|allow</dt><dd>DiskUse#ALLOW</dd>
+	 *     <dt>false|deny</dt><dd>DiskUse#DENY</dd>
+	 * </dl>
 	 *
 	 * @return {@literal false} by default.
 	 * @since 3.0
-	 * @see Aggregation
+	 * @see org.springframework.data.mongodb.core.query.DiskUse
 	 */
-	boolean allowDiskUse() default false;
+	String allowDiskUse() default "";
 
 }

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

@@ -26,6 +26,7 @@ import org.springframework.data.mongodb.core.ExecutableFindOperation.FindWithQue
 import org.springframework.data.mongodb.core.MongoOperations;
 import org.springframework.data.mongodb.core.annotation.Collation;
 import org.springframework.data.mongodb.core.query.BasicQuery;
+import org.springframework.data.mongodb.core.query.DiskUse;
 import org.springframework.data.mongodb.repository.Hint;
 import org.springframework.data.mongodb.repository.Meta;
 import org.springframework.data.mongodb.repository.query.MongoQueryExecution.PagedExecution;
@@ -292,6 +293,12 @@ class QueryBlocks {
 				if (StringUtils.hasText(comment)) {
 					builder.addStatement("$L.comment($S)", queryVariableName, comment);
 				}
+
+				String allowDiskUse = metaAnnotation.getString("allowDiskUse");
+				if (StringUtils.hasText(allowDiskUse)) {
+					DiskUse diskUse = DiskUse.of(allowDiskUse);
+					builder.addStatement("$L.diskUse($T.$L)", queryVariableName, DiskUse.class, diskUse.name());
+				}
 			}
 
 			MergedAnnotation<Collation> collationAnnotation = context.getAnnotation(Collation.class);

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

@@ -27,6 +27,7 @@ import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mongodb.core.annotation.Collation;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.data.mongodb.core.query.DiskUse;
 import org.springframework.data.mongodb.core.query.UpdateDefinition;
 import org.springframework.data.mongodb.repository.Aggregation;
 import org.springframework.data.mongodb.repository.Hint;
@@ -272,8 +273,9 @@ public class MongoQueryMethod extends QueryMethod {
 			}
 		}
 
-		if (meta.allowDiskUse()) {
-			metaAttributes.setAllowDiskUse(meta.allowDiskUse());
+		DiskUse diskUse = DiskUse.of(meta.allowDiskUse());
+		if (!diskUse.equals(DiskUse.DEFAULT)) {
+			metaAttributes.setAllowDiskUse(diskUse.equals(DiskUse.ALLOW));
 		}
 
 		return metaAttributes;

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/aot/MongoRepositoryContributorUnitTests.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.data.mongodb.repository.aot;
 
-import static org.mockito.Mockito.*;
-import static org.springframework.data.mongodb.test.util.Assertions.*;
+import static org.mockito.Mockito.mock;
+import static org.springframework.data.mongodb.test.util.Assertions.assertThat;
 
 import example.aot.User;
 import example.aot.UserRepository;
@@ -25,7 +25,6 @@ import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 
 import org.junit.jupiter.api.Test;
-
 import org.springframework.aot.generate.GeneratedFiles;
 import org.springframework.aot.test.generate.TestGenerationContext;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -42,8 +41,8 @@ import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
  * Unit tests for the {@link UserRepository} fragment sources via {@link MongoRepositoryContributor}.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  */
-
 @SpringJUnitConfig(classes = MongoRepositoryContributorUnitTests.MongoRepositoryContributorConfiguration.class)
 class MongoRepositoryContributorUnitTests {
 
@@ -63,7 +62,7 @@ class MongoRepositoryContributorUnitTests {
 
 	@Autowired TestGenerationContext generationContext;
 
-	@Test // GH-4970
+	@Test // GH-4970, GH-4667
 	void shouldConsiderMetaAnnotation() throws IOException {
 
 		InputStreamSource aotFragment = generationContext.getGeneratedFiles().getGeneratedFile(GeneratedFiles.Kind.SOURCE,
@@ -74,6 +73,7 @@ class MongoRepositoryContributorUnitTests {
 		assertThat(content).contains("filterQuery.maxTimeMsec(555)");
 		assertThat(content).contains("filterQuery.cursorBatchSize(1234)");
 		assertThat(content).contains("filterQuery.comment(\"foo\")");
+		assertThat(content).contains("filterQuery.diskUse(DiskUse.DENY)");
 	}
 
 	interface MetaUserRepository extends CrudRepository<User, String> {
@@ -81,7 +81,7 @@ class MongoRepositoryContributorUnitTests {
 		@Meta
 		User findAllByLastname(String lastname);
 
-		@Meta(cursorBatchSize = 1234, comment = "foo", maxExecutionTimeMs = 555)
+		@Meta(cursorBatchSize = 1234, comment = "foo", maxExecutionTimeMs = 555, allowDiskUse = "false")
 		User findWithMetaAllByLastname(String lastname);
 	}
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/StringBasedAggregationUnitTests.java

@@ -349,7 +349,7 @@ public class StringBasedAggregationUnitTests {
 
 	private interface SampleRepository extends Repository<Person, Long> {
 
-		@Meta(cursorBatchSize = 42, comment = "expensive-aggregation", allowDiskUse = true, maxExecutionTimeMs = 100)
+		@Meta(cursorBatchSize = 42, comment = "expensive-aggregation", allowDiskUse = "true", maxExecutionTimeMs = 100)
 		@Aggregation({ RAW_GROUP_BY_LASTNAME_STRING, RAW_SORT_STRING })
 		PersonAggregate plainStringAggregation();