Switch from boolean to String for allowDiskUse flag.

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>5.0.0-SNAPSHOT</version>
+	<version>5.0.x-GH-4667-SNAPSHOT</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data MongoDB</name>

spring-data-mongodb-distribution/pom.xml

@@ -15,7 +15,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>5.0.0-SNAPSHOT</version>
+		<version>5.0.x-GH-4667-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb/pom.xml

@@ -13,7 +13,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>5.0.0-SNAPSHOT</version>
+		<version>5.0.x-GH-4667-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

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

@@ -23,6 +23,7 @@
 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 AggregationOptions(boolean allowDiskUse, boolean explain, @Nullable Docum
 		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 AggregationOptions(boolean allowDiskUse, boolean explain, @Nullable Docum
 	 */
 	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 AggregationOptions(boolean allowDiskUse, boolean explain, @Nullable Docum
 	 */
 	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 AggregationOptions(boolean allowDiskUse, boolean explain, @Nullable Docum
 	 * @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 static AggregationOptions fromDocument(Document document) {
 		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 static Builder builder() {
 	 * @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 boolean isAllowDiskUse() {
 	 * @since 4.2.5
 	 */
 	public boolean isAllowDiskUseSet() {
-		return allowDiskUse.isPresent();
+		return !diskUse.equals(DiskUse.DEFAULT);
 	}
 
 	/**
@@ -427,7 +442,7 @@ static Document createCursor(int cursorBatchSize) {
 	 */
 	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 static class Builder {
 		 */
 		@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 Builder noMapping() {
 		@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 +1,41 @@
+/*
+ * 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;
+
+/**
+ * @author Christoph Strobl
+ */
+public enum DiskUse {
+
+	DEFAULT, ALLOW, DENY;
+
+	public static DiskUse of(@Nullable Boolean value) {
+		return value != null ? (value ? ALLOW : DENY) : DEFAULT;
+	}
+
+	public static DiskUse of(String value) {
+		if (!StringUtils.hasText(value)) {
+			return DEFAULT;
+		}
+		if (value.toLowerCase().equalsIgnoreCase("true")) {
+			return ALLOW;
+		}
+		return valueOf(value.toUpperCase());
+	}
+}

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

@@ -51,7 +51,7 @@ private enum MetaKey {
 	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 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 Set<CursorOption> getFlags() {
 	 */
 	@Nullable
 	public Boolean getAllowDiskUse() {
-		return allowDiskUse;
+		return diskUse.equals(DiskUse.DEFAULT) ? null : diskUse.equals(DiskUse.ALLOW);
 	}
 
 	/**
@@ -244,14 +244,18 @@ public Boolean getAllowDiskUse() {
 	 * @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 Query comment(String comment) {
 	 */
 	@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

@@ -74,6 +74,6 @@
 	 * @since 3.0
 	 * @see Aggregation
 	 */
-	boolean allowDiskUse() default false;
+	String allowDiskUse() default "";
 
 }

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

@@ -27,6 +27,7 @@
 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 org.springframework.data.mongodb.core.query.Meta getQueryMetaAttributes()
 			}
 		}
 
-		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/query/StringBasedAggregationUnitTests.java

@@ -349,7 +349,7 @@ private Class<?> targetTypeOf(AggregationInvocation invocation) {
 
 	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();