Add support for Wildcard Index.

Add WildcardIndexed annotation and the programatic WildcardIndex.

Closes #3225
Original pull request: #3671.

Author: christophstrobl

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

@@ -115,6 +115,10 @@ private static Converter<IndexDefinition, IndexOptions> getIndexDefinitionIndexO
 				ops = ops.collation(fromDocument(indexOptions.get("collation", Document.class)));
 			}
 
+			if(indexOptions.containsKey("wildcardProjection")) {
+				ops.wildcardProjection(indexOptions.get("wildcardProjection", Document.class));
+			}
+
 			return ops;
 		};
 	}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/IndexField.java

@@ -29,7 +29,7 @@
 public final class IndexField {
 
 	enum Type {
-		GEO, TEXT, DEFAULT, HASH;
+		GEO, TEXT, DEFAULT, HASH, WILDCARD;
 	}
 
 	private final String key;
@@ -48,7 +48,7 @@ private IndexField(String key, @Nullable Direction direction, @Nullable Type typ
 		if (Type.GEO.equals(type) || Type.TEXT.equals(type)) {
 			Assert.isNull(direction, "Geo/Text indexes must not have a direction!");
 		} else {
-			if (!Type.HASH.equals(type)) {
+			if (!(Type.HASH.equals(type) || Type.WILDCARD.equals(type))) {
 				Assert.notNull(direction, "Default indexes require a direction");
 			}
 		}
@@ -77,6 +77,17 @@ static IndexField hashed(String key) {
 		return new IndexField(key, null, Type.HASH);
 	}
 
+	/**
+	 * Creates a {@literal wildcard} {@link IndexField} for the given key.
+	 *
+	 * @param key must not be {@literal null} or empty.
+	 * @return new instance of {@link IndexField}.
+	 * @since 3.3
+	 */
+	static IndexField wildcard(String key) {
+		return new IndexField(key, null, Type.WILDCARD);
+	}
+
 	/**
 	 * Creates a geo {@link IndexField} for the given key.
 	 *
@@ -142,6 +153,16 @@ public boolean isHashed() {
 		return Type.HASH.equals(type);
 	}
 
+	/**
+	 * Returns whether the {@link IndexField} is contains a {@literal wildcard} expression.
+	 *
+	 * @return {@literal true} if {@link IndexField} contains a wildcard {@literal $**}.
+	 * @since 3.3
+	 */
+	public boolean isWildcard() {
+		return Type.WILDCARD.equals(type);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see java.lang.Object#equals(java.lang.Object)

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/IndexInfo.java

@@ -55,6 +55,7 @@ public class IndexInfo {
 	private @Nullable Duration expireAfter;
 	private @Nullable String partialFilterExpression;
 	private @Nullable Document collation;
+	private @Nullable Document wildcardProjection;
 
 	public IndexInfo(List<IndexField> indexFields, String name, boolean unique, boolean sparse, String language) {
 
@@ -99,6 +100,8 @@ public static IndexInfo indexInfoOf(Document sourceDocument) {
 
 				if (ObjectUtils.nullSafeEquals("hashed", value)) {
 					indexFields.add(IndexField.hashed(key));
+				} else if (key.contains("$**")) {
+					indexFields.add(IndexField.wildcard(key));
 				} else {
 
 					Double keyValue = new Double(value.toString());
@@ -131,6 +134,10 @@ public static IndexInfo indexInfoOf(Document sourceDocument) {
 			info.expireAfter = Duration.ofSeconds(NumberUtils.convertNumberToTargetClass(expireAfterSeconds, Long.class));
 		}
 
+		if (sourceDocument.containsKey("wildcardProjection")) {
+			info.wildcardProjection = sourceDocument.get("wildcardProjection", Document.class);
+		}
+
 		return info;
 	}
 
@@ -216,6 +223,16 @@ public Optional<Document> getCollation() {
 		return Optional.ofNullable(collation);
 	}
 
+	/**
+	 * Get {@literal wildcardProjection} information.
+	 *
+	 * @return {@link Optional#empty() empty} if not set.
+	 * @since 3.3
+	 */
+	public Optional<Document> getWildcardProjection() {
+		return Optional.ofNullable(wildcardProjection);
+	}
+
 	/**
 	 * Get the duration after which documents within the index expire.
 	 *
@@ -234,6 +251,14 @@ public boolean isHashed() {
 		return getIndexFields().stream().anyMatch(IndexField::isHashed);
 	}
 
+	/**
+	 * @return {@literal true} if a wildcard index field is present.
+	 * @since 3.3
+	 */
+	public boolean isWildcard() {
+		return getIndexFields().stream().anyMatch(IndexField::isWildcard);
+	}
+
 	@Override
 	public String toString() {
 
@@ -303,4 +328,5 @@ public boolean equals(Object obj) {
 		}
 		return true;
 	}
+
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/MongoPersistentEntityIndexResolver.java

@@ -46,6 +46,7 @@
 import org.springframework.data.mongodb.core.mapping.Document;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.data.mongodb.core.query.Collation;
 import org.springframework.data.mongodb.util.BsonUtils;
 import org.springframework.data.mongodb.util.DotPath;
 import org.springframework.data.spel.EvaluationContextProvider;
@@ -121,6 +122,7 @@ public List<IndexDefinitionHolder> resolveIndexForEntity(MongoPersistentEntity<?
 		List<IndexDefinitionHolder> indexInformation = new ArrayList<>();
 		String collection = root.getCollection();
 		indexInformation.addAll(potentiallyCreateCompoundIndexDefinitions("", collection, root));
+		indexInformation.addAll(potentiallyCreateWildcardIndexDefinitions("", collection, root));
 		indexInformation.addAll(potentiallyCreateTextIndexDefinition(root, collection));
 
 		root.doWithProperties((PropertyHandler<MongoPersistentProperty>) property -> this
@@ -162,17 +164,18 @@ private void potentiallyAddIndexForProperty(MongoPersistentEntity<?> root, Mongo
 	 * @return List of {@link IndexDefinitionHolder} representing indexes for given type and its referenced property
 	 *         types. Will never be {@code null}.
 	 */
-	private List<IndexDefinitionHolder> resolveIndexForClass( TypeInformation<?> type,  String dotPath,
-			 Path path,  String collection,  CycleGuard guard) {
+	private List<IndexDefinitionHolder> resolveIndexForClass(TypeInformation<?> type, String dotPath, Path path,
+			String collection, CycleGuard guard) {
 
 		return resolveIndexForEntity(mappingContext.getRequiredPersistentEntity(type), dotPath, path, collection, guard);
 	}
 
-	private List<IndexDefinitionHolder> resolveIndexForEntity(MongoPersistentEntity<?> entity,  String dotPath,
-			 Path path,  String collection,  CycleGuard guard) {
+	private List<IndexDefinitionHolder> resolveIndexForEntity(MongoPersistentEntity<?> entity, String dotPath, Path path,
+			String collection, CycleGuard guard) {
 
 		List<IndexDefinitionHolder> indexInformation = new ArrayList<>();
 		indexInformation.addAll(potentiallyCreateCompoundIndexDefinitions(dotPath, collection, entity));
+		indexInformation.addAll(potentiallyCreateWildcardIndexDefinitions(dotPath, collection, entity));
 
 		entity.doWithProperties((PropertyHandler<MongoPersistentProperty>) property -> this
 				.guardAndPotentiallyAddIndexForProperty(property, dotPath, path, collection, indexInformation, guard));
@@ -196,15 +199,15 @@ private void guardAndPotentiallyAddIndexForProperty(MongoPersistentProperty pers
 
 		if (persistentProperty.isEntity()) {
 			try {
-				indexes.addAll(resolveIndexForEntity(mappingContext.getPersistentEntity(persistentProperty), propertyDotPath.toString(),
-						propertyPath, collection, guard));
+				indexes.addAll(resolveIndexForEntity(mappingContext.getPersistentEntity(persistentProperty),
+						propertyDotPath.toString(), propertyPath, collection, guard));
 			} catch (CyclicPropertyReferenceException e) {
 				LOGGER.info(e.getMessage());
 			}
 		}
 
-		List<IndexDefinitionHolder> indexDefinitions = createIndexDefinitionHolderForProperty(propertyDotPath.toString(), collection,
-				persistentProperty);
+		List<IndexDefinitionHolder> indexDefinitions = createIndexDefinitionHolderForProperty(propertyDotPath.toString(),
+				collection, persistentProperty);
 
 		if (!indexDefinitions.isEmpty()) {
 			indexes.addAll(indexDefinitions);
@@ -232,6 +235,11 @@ private List<IndexDefinitionHolder> createIndexDefinitionHolderForProperty(Strin
 		if (persistentProperty.isAnnotationPresent(HashIndexed.class)) {
 			indices.add(createHashedIndexDefinition(dotPath, collection, persistentProperty));
 		}
+		if (persistentProperty.isAnnotationPresent(WildcardIndexed.class)) {
+			indices.add(createWildcardIndexDefinition(dotPath, collection,
+					persistentProperty.getRequiredAnnotation(WildcardIndexed.class),
+					mappingContext.getPersistentEntity(persistentProperty)));
+		}
 
 		return indices;
 	}
@@ -246,6 +254,18 @@ private List<IndexDefinitionHolder> potentiallyCreateCompoundIndexDefinitions(St
 		return createCompoundIndexDefinitions(dotPath, collection, entity);
 	}
 
+	private List<IndexDefinitionHolder> potentiallyCreateWildcardIndexDefinitions(String dotPath, String collection,
+			MongoPersistentEntity<?> entity) {
+
+		if (entity.findAnnotation(WildcardIndexed.class) == null) {
+			return Collections.emptyList();
+		}
+
+		return Collections.singletonList(new IndexDefinitionHolder(dotPath,
+				createWildcardIndexDefinition(dotPath, collection, entity.getRequiredAnnotation(WildcardIndexed.class), entity),
+				collection));
+	}
+
 	private Collection<? extends IndexDefinitionHolder> potentiallyCreateTextIndexDefinition(
 			MongoPersistentEntity<?> root, String collection) {
 
@@ -292,9 +312,8 @@ private Collection<? extends IndexDefinitionHolder> potentiallyCreateTextIndexDe
 
 	}
 
-	private void appendTextIndexInformation(DotPath dotPath, Path path,
-			TextIndexDefinitionBuilder indexDefinitionBuilder, MongoPersistentEntity<?> entity,
-			TextIndexIncludeOptions includeOptions, CycleGuard guard) {
+	private void appendTextIndexInformation(DotPath dotPath, Path path, TextIndexDefinitionBuilder indexDefinitionBuilder,
+			MongoPersistentEntity<?> entity, TextIndexIncludeOptions includeOptions, CycleGuard guard) {
 
 		entity.doWithProperties(new PropertyHandler<MongoPersistentProperty>() {
 
@@ -311,8 +330,7 @@ public void doWithPersistentProperty(MongoPersistentProperty persistentProperty)
 
 				if (includeOptions.isForce() || indexed != null || persistentProperty.isEntity()) {
 
-					DotPath propertyDotPath = dotPath
-							.append(persistentProperty.getFieldName());
+					DotPath propertyDotPath = dotPath.append(persistentProperty.getFieldName());
 
 					Path propertyPath = path.append(persistentProperty);
 
@@ -406,6 +424,32 @@ protected IndexDefinitionHolder createCompoundIndexDefinition(String dotPath, St
 		return new IndexDefinitionHolder(dotPath, indexDefinition, collection);
 	}
 
+	protected IndexDefinitionHolder createWildcardIndexDefinition(String dotPath, String collection,
+			WildcardIndexed index, @Nullable MongoPersistentEntity<?> entity) {
+
+		WildcardIndex indexDefinition = new WildcardIndex(dotPath);
+
+		if (StringUtils.hasText(index.wildcardProjection())) {
+			indexDefinition.wildcardProjection(evaluateWildcardProjection(index.wildcardProjection(), entity));
+		}
+
+		if (!index.useGeneratedName()) {
+			indexDefinition.named(pathAwareIndexName(index.name(), dotPath, entity, null));
+		}
+
+		if (StringUtils.hasText(index.partialFilter())) {
+			indexDefinition.partial(evaluatePartialFilter(index.partialFilter(), entity));
+		}
+
+		if (StringUtils.hasText(index.collation())) {
+			indexDefinition.collation(evaluateCollation(index.collation(), entity));
+		} else if (entity != null && entity.hasCollation()) {
+			indexDefinition.collation(entity.getCollation());
+		}
+
+		return new IndexDefinitionHolder(dotPath, indexDefinition, collection);
+	}
+
 	private org.bson.Document resolveCompoundIndexKeyFromStringDefinition(String dotPath, String keyDefinitionString,
 			PersistentEntity<?, ?> entity) {
 
@@ -510,6 +554,33 @@ private PartialIndexFilter evaluatePartialFilter(String filterExpression, Persis
 		return PartialIndexFilter.of(BsonUtils.parse(filterExpression, null));
 	}
 
+	private org.bson.Document evaluateWildcardProjection(String projectionExpression, PersistentEntity<?, ?> entity) {
+
+		Object result = evaluate(projectionExpression, getEvaluationContextForProperty(entity));
+
+		if (result instanceof org.bson.Document) {
+			return (org.bson.Document) result;
+		}
+
+		return BsonUtils.parse(projectionExpression, null);
+	}
+
+	private Collation evaluateCollation(String collationExpression, PersistentEntity<?, ?> entity) {
+
+		Object result = evaluate(collationExpression, getEvaluationContextForProperty(entity));
+		if (result instanceof org.bson.Document) {
+			return Collation.from((org.bson.Document) result);
+		}
+		if (result instanceof Collation) {
+			return (Collation) result;
+		}
+		if (result instanceof String) {
+			return Collation.parse(result.toString());
+		}
+		throw new IllegalStateException("Cannot parse collation " + result);
+
+	}
+
 	/**
 	 * Creates {@link HashedIndex} wrapped in {@link IndexDefinitionHolder} out of {@link HashIndexed} for a given
 	 * {@link MongoPersistentProperty}.
@@ -657,8 +728,8 @@ private void resolveAndAddIndexesForAssociation(Association<MongoPersistentPrope
 							propertyDotPath));
 		}
 
-		List<IndexDefinitionHolder> indexDefinitions = createIndexDefinitionHolderForProperty(propertyDotPath.toString(), collection,
-				property);
+		List<IndexDefinitionHolder> indexDefinitions = createIndexDefinitionHolderForProperty(propertyDotPath.toString(),
+				collection, property);
 
 		if (!indexDefinitions.isEmpty()) {
 			indexes.addAll(indexDefinitions);
@@ -998,6 +1069,11 @@ public org.bson.Document getIndexKeys() {
 		public org.bson.Document getIndexOptions() {
 			return indexDefinition.getIndexOptions();
 		}
+
+		@Override
+		public String toString() {
+			return "IndexDefinitionHolder{" + "indexKeys=" + getIndexKeys() + '}';
+		}
 	}
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/WildcardIndex.java

@@ -0,0 +1,198 @@
+/*
+ * 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.mongodb.core.index;
+
+import java.time.Duration;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import org.bson.Document;
+import org.springframework.lang.Nullable;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
+
+/**
+ * {@link WildcardIndex} is a specific {@link Index} that can be used to include all fields into an index based on the
+ * {@code $**" : 1} pattern on a root object (the one typically carrying the
+ * {@link org.springframework.data.mongodb.core.mapping.Document} annotation). On those it is possible to use
+ * {@link #wildcardProjectionInclude(String...)} and {@link #wildcardProjectionExclude(String...)} to define specific
+ * paths for in-/exclusion.
+ * <p />
+ * It can also be used to define an index on a specific field path and its subfields, e.g.
+ * {@code "path.to.field.$**" : 1}. <br />
+ * Note that {@literal wildcardProjections} are not allowed in this case.
+ * <p />
+ * <strong>LIMITATIONS</strong><br />
+ * <ul>
+ * <li>{@link #unique() Unique} and {@link #expire(long) ttl} options are not supported.</li>
+ * <li>Keys used for sharding must not be included</li>
+ * <li>Cannot be used to generate any type of geo index.</li>
+ * </ul>
+ *
+ * @author Christoph Strobl
+ * @see <a href= "https://docs.mongodb.com/manual/core/index-wildcard/">MongoDB Reference Documentation: Wildcard
+ *      Indexes/</a>
+ * @since 3.3
+ */
+public class WildcardIndex extends Index {
+
+	private @Nullable String fieldName;
+	private Map<String, Object> wildcardProjection = new LinkedHashMap<>();
+
+	/**
+	 * Create a new instance of {@link WildcardIndex} using {@code $**}.
+	 */
+	public WildcardIndex() {}
+
+	/**
+	 * Create a new instance of {@link WildcardIndex} for the given {@literal path}. If no {@literal path} is provided the
+	 * index will be considered a root one using {@code $**}. <br />
+	 * <strong>NOTE</strong> {@link #wildcardProjectionInclude(String...)}, {@link #wildcardProjectionExclude(String...)}
+	 * can only be used for top level index definitions having an {@literal empty} or {@literal null} path.
+	 *
+	 * @param path can be {@literal null}. If {@literal null} all fields will be indexed.
+	 */
+	public WildcardIndex(@Nullable String path) {
+		this.fieldName = path;
+	}
+
+	/**
+	 * Include the {@code _id} field in {@literal wildcardProjection}.
+	 *
+	 * @return this.
+	 */
+	public WildcardIndex includeId() {
+
+		wildcardProjection.put("_id", 1);
+		return this;
+	}
+
+	/**
+	 * Set the index name to use.
+	 *
+	 * @param name
+	 * @return this.
+	 */
+	@Override
+	public WildcardIndex named(String name) {
+
+		super.named(name);
+		return this;
+	}
+
+	/**
+	 * Unique option is not supported.
+	 *
+	 * @throws UnsupportedOperationException
+	 */
+	@Override
+	public Index unique() {
+		throw new UnsupportedOperationException("Wildcard Index does not support 'unique'.");
+	}
+
+	/**
+	 * ttl option is not supported.
+	 *
+	 * @throws UnsupportedOperationException
+	 */
+	@Override
+	public Index expire(long seconds) {
+		throw new UnsupportedOperationException("Wildcard Index does not support 'ttl'.");
+	}
+
+	/**
+	 * ttl option is not supported.
+	 *
+	 * @throws UnsupportedOperationException
+	 */
+	@Override
+	public Index expire(long value, TimeUnit timeUnit) {
+		throw new UnsupportedOperationException("Wildcard Index does not support 'ttl'.");
+	}
+
+	/**
+	 * ttl option is not supported.
+	 *
+	 * @throws UnsupportedOperationException
+	 */
+	@Override
+	public Index expire(Duration duration) {
+		throw new UnsupportedOperationException("Wildcard Index does not support 'ttl'.");
+	}
+
+	/**
+	 * Add fields to be included from indexing via {@code wildcardProjection}. <br />
+	 * This option is only allowed on {@link WildcardIndex#WildcardIndex() top level} wildcard indexes.
+	 *
+	 * @param paths must not be {@literal null}.
+	 * @return this.
+	 */
+	public WildcardIndex wildcardProjectionInclude(String... paths) {
+
+		for (String path : paths) {
+			wildcardProjection.put(path, 1);
+		}
+		return this;
+	}
+
+	/**
+	 * Add fields to be excluded from indexing via {@code wildcardProjection}. <br />
+	 * This option is only allowed on {@link WildcardIndex#WildcardIndex() top level} wildcard indexes.
+	 *
+	 * @param paths must not be {@literal null}.
+	 * @return this.
+	 */
+	public WildcardIndex wildcardProjectionExclude(String... paths) {
+
+		for (String path : paths) {
+			wildcardProjection.put(path, 0);
+		}
+		return this;
+	}
+
+	/**
+	 * Set the fields to be in-/excluded from indexing via {@code wildcardProjection}. <br />
+	 * This option is only allowed on {@link WildcardIndex#WildcardIndex() top level} wildcard indexes.
+	 *
+	 * @param includeExclude must not be {@literal null}.
+	 * @return this.
+	 */
+	public WildcardIndex wildcardProjection(Map<String, Object> includeExclude) {
+
+		wildcardProjection.putAll(includeExclude);
+		return this;
+	}
+
+	private String getTargetFieldName() {
+		return StringUtils.hasText(fieldName) ? (fieldName + ".$**") : "$**";
+	}
+
+	@Override
+	public Document getIndexKeys() {
+		return new Document(getTargetFieldName(), 1);
+	}
+
+	@Override
+	public Document getIndexOptions() {
+
+		Document options = new Document(super.getIndexOptions());
+		if (!CollectionUtils.isEmpty(wildcardProjection)) {
+			options.put("wildcardProjection", new Document(wildcardProjection));
+		}
+		return options;
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/index/WildcardIndexed.java

@@ -0,0 +1,130 @@
+/*
+ * 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.mongodb.core.index;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation for an entity or property that should be used as key for a
+ * <a href="https://docs.mongodb.com/manual/core/index-wildcard/">Wildcard Index</a>. <br />
+ * If placed on a {@link ElementType#TYPE type} that is a root level domain entity (one having an
+ * {@link org.springframework.data.mongodb.core.mapping.Document} annotation) will advise the index creator to create a
+ * wildcard index for it.
+ *
+ * <pre class="code">
+ *
+ * &#64;Document
+ * &#64;WildcardIndexed
+ * public class Product {
+ *     ...
+ * }
+ *
+ * db.product.createIndex({ "$**" : 1 } , {})
+ * </pre>
+ * 
+ * {@literal wildcardProjection} can be used to specify keys to in-/exclude in the index.
+ *
+ * <pre class="code">
+ *
+ * &#64;Document
+ * &#64;WildcardIndexed(wildcardProjection = "{ 'userMetadata.age' : 0 }")
+ * public class User {
+ *     private &#64;Id String id;
+ *     private UserMetadata userMetadata;
+ * }
+ *
+ *
+ * db.user.createIndex(
+ *   { "$**" : 1 },
+ *   { "wildcardProjection" :
+ *     { "userMetadata.age" : 0 }
+ *   }
+ * )
+ * </pre>
+ *
+ * Wildcard indexes can also be expressed by adding the annotation directly to the field. Please note that
+ * {@literal wildcardProjection} is not allowed on nested paths.
+ *
+ * <pre class="code">
+ * &#64;Document
+ * public class User {
+ * 
+ *     private &#64;Id String id;
+ *
+ *     &#64;WildcardIndexed
+ *     private UserMetadata userMetadata;
+ * }
+ *
+ *
+ * db.user.createIndex({ "userMetadata.$**" : 1 }, {})
+ * </pre>
+ *
+ * @author Christoph Strobl
+ * @since 3.3
+ */
+@Documented
+@Target({ ElementType.TYPE, ElementType.FIELD })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface WildcardIndexed {
+
+	/**
+	 * Index name either as plain value or as {@link org.springframework.expression.spel.standard.SpelExpression template
+	 * expression}. <br />
+	 * <br />
+	 * The name will only be applied as is when defined on root level. For usage on nested or embedded structures the
+	 * provided name will be prefixed with the path leading to the entity. <br />
+	 * 
+	 * @return
+	 */
+	String name() default "";
+
+	/**
+	 * If set to {@literal true} then MongoDB will ignore the given index name and instead generate a new name. Defaults
+	 * to {@literal false}.
+	 *
+	 * @return {@literal false} by default.
+	 */
+	boolean useGeneratedName() default false;
+
+	/**
+	 * Only index the documents in a collection that meet a specified {@link IndexFilter filter expression}. <br />
+	 *
+	 * @return empty by default.
+	 * @see <a href=
+	 *      "https://docs.mongodb.com/manual/core/index-partial/">https://docs.mongodb.com/manual/core/index-partial/</a>
+	 */
+	String partialFilter() default "";
+
+	/**
+	 * Explicitly specify sub fields to be in-/excluded as a {@link org.bson.Document#parse(String) prasable} String.
+	 * <br />
+	 * <strong>NOTE: </strong>Can only be done on root level documents.
+	 * 
+	 * @return empty by default.
+	 */
+	String wildcardProjection() default "";
+
+	/**
+	 * Defines the collation to apply.
+	 *
+	 * @return an empty {@link String} by default.
+	 */
+	String collation() default "";
+}

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/index/IndexInfoUnitTests.java

@@ -36,6 +36,7 @@ public class IndexInfoUnitTests {
 	static final String INDEX_WITH_PARTIAL_FILTER = "{ \"v\" : 2, \"key\" : { \"k3y\" : 1 }, \"name\" : \"partial-filter-index\", \"ns\" : \"db.collection\", \"partialFilterExpression\" : { \"quantity\" : { \"$gte\" : 10 } } }";
 	static final String INDEX_WITH_EXPIRATION_TIME = "{ \"v\" : 2, \"key\" : { \"lastModifiedDate\" : 1 },\"name\" : \"expire-after-last-modified\", \"ns\" : \"db.collectio\", \"expireAfterSeconds\" : 3600 }";
 	static final String HASHED_INDEX = "{ \"v\" : 2, \"key\" : { \"score\" : \"hashed\" }, \"name\" : \"score_hashed\", \"ns\" : \"db.collection\" }";
+	static final String WILDCARD_INDEX = "{ \"v\" : 2, \"key\" : { \"$**\" : 1 }, \"name\" : \"$**_1\", \"wildcardProjection\" : { \"fieldA\" : 0, \"fieldB.fieldC\" : 0 } }";
 
 	@Test
 	public void isIndexForFieldsCorrectly() {
@@ -79,6 +80,16 @@ public void hashedIndexIsMarkedAsSuch() {
 		assertThat(getIndexInfo(HASHED_INDEX).isHashed()).isTrue();
 	}
 
+	@Test // GH-3225
+	public void identifiesWildcardIndexCorrectly() {
+		assertThat(getIndexInfo(WILDCARD_INDEX).isWildcard()).isTrue();
+	}
+
+	@Test // GH-3225
+	public void readsWildcardIndexProjectionCorrectly() {
+		assertThat(getIndexInfo(WILDCARD_INDEX).getWildcardProjection()).contains(new Document("fieldA", 0).append("fieldB.fieldC", 0));
+	}
+
 	private static IndexInfo getIndexInfo(String documentJson) {
 		return IndexInfo.indexInfoOf(Document.parse(documentJson));
 	}

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/index/MongoPersistentEntityIndexResolverUnitTests.java

@@ -15,8 +15,9 @@
  */
 package org.springframework.data.mongodb.core.index;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.*;
-import static org.springframework.data.mongodb.test.util.Assertions.*;
+import static org.springframework.data.mongodb.test.util.Assertions.assertThatExceptionOfType;
 
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
@@ -25,6 +26,7 @@
 import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -1323,6 +1325,49 @@ public void errorsOnIndexOnEmbedded() {
 
 		}
 
+		@Test // GH-3225
+		public void resolvesWildcardOnRoot() {
+
+			List<IndexDefinitionHolder> indices = prepareMappingContextAndResolveIndexForType(
+					WithWildCardIndexOnEntity.class);
+			assertThat(indices).hasSize(1);
+			assertThat(indices.get(0)).satisfies(it -> {
+				assertThat(it.getIndexKeys()).containsEntry("$**", 1);
+			});
+		}
+
+		@Test // GH-3225
+		public void resolvesWildcardOnProperty() {
+
+			List<IndexDefinitionHolder> indices = prepareMappingContextAndResolveIndexForType(
+					WithWildCardIndexOnProperty.class);
+			assertThat(indices).hasSize(3);
+			assertThat(indices.get(0)).satisfies(it -> {
+				assertThat(it.getIndexKeys()).containsEntry("value.$**", 1);
+			});
+			assertThat(indices.get(1)).satisfies(it -> {
+				assertThat(it.getIndexKeys()).containsEntry("the_field.$**", 1);
+			});
+			assertThat(indices.get(2)).satisfies(it -> {
+				assertThat(it.getIndexKeys()).containsEntry("withOptions.$**", 1);
+				assertThat(it.getIndexOptions()).containsEntry("name",
+						"withOptions.idx")
+				.containsEntry("collation", new org.bson.Document("locale", "en_US"))
+				.containsEntry("partialFilterExpression", new org.bson.Document("$eq", 1));
+			});
+		}
+
+		@Test // GH-3225
+		public void resolvesWildcardTypeOfNestedProperty() {
+
+			List<IndexDefinitionHolder> indices = prepareMappingContextAndResolveIndexForType(
+					WithWildCardOnEntityOfNested.class);
+			assertThat(indices).hasSize(1);
+			assertThat(indices.get(0)).satisfies(it -> {
+				assertThat(it.getIndexKeys()).containsEntry("value.$**", 1);
+			});
+		}
+
 		@Document
 		class MixedIndexRoot {
 
@@ -1533,7 +1578,7 @@ class InvalidIndexOnUnwrapped {
 
 			@Indexed //
 			@Unwrapped.Nullable //
-					UnwrappableType unwrappableType;
+			UnwrappableType unwrappableType;
 
 		}
 
@@ -1573,6 +1618,42 @@ class WithHashedIndex {
 			@HashIndexed String value;
 		}
 
+		@Document
+		@WildcardIndexed
+		class WithWildCardIndexOnEntity {
+
+			String value;
+		}
+
+		@Document
+		@WildcardIndexed(wildcardProjection = "{'_id' : 1, 'value' : 0}")
+		class WithWildCardIndexHavingProjectionOnEntity {
+
+			String value;
+		}
+
+		@Document
+		class WithWildCardIndexOnProperty {
+
+			@WildcardIndexed //
+			Map<String, String> value;
+
+			@WildcardIndexed //
+			@Field("the_field") //
+			Map<String, String> renamedField;
+
+			@WildcardIndexed(name = "idx", partialFilter = "{ '$eq' : 1 }", collation = "en_US") //
+			Map<String, String> withOptions;
+
+		}
+
+		@Document
+		class WithWildCardOnEntityOfNested {
+
+			WithWildCardIndexOnEntity value;
+
+		}
+
 		@Document
 		class WithHashedIndexAndIndex {
 

src/main/asciidoc/reference/mapping.adoc

@@ -760,6 +760,94 @@ mongoOperations.indexOpsFor(Jedi.class)
 ----
 ====
 
+[[mapping-usage-indexes.wildcard-index]]
+=== Wildcard Indexes
+
+A `WildcardIndex` is an index that can be used to include all fields or specific ones based a given (wildcard) pattern.
+For details, refer to the https://docs.mongodb.com/manual/core/index-wildcard/[MongoDB Documentation].
+
+The index can be set up programmatically using `WildcardIndex` via `IndexOperations`.
+
+.Programmatic WildcardIndex setup
+====
+[source,java]
+----
+mongoOperations
+    .indexOps(User.class)
+    .ensureIndex(new WildcardIndex("userMetadata"));
+----
+[source,javascript]
+----
+db.user.createIndex({ "userMetadata.$**" : 1 }, {})
+----
+====
+
+The `@WildcardIndex` annotation allows a declarative index setup an can be added on either a type or property.
+
+If placed on a type that is a root level domain entity (one having an `@Document` annotation) will advise the index creator to create a
+wildcard index for it.
+
+.Wildcard index on domain type
+====
+[source,java]
+----
+@Document
+@WildcardIndexed
+public class Product {
+    ...
+}
+----
+[source,javascript]
+----
+db.product.createIndex({ "$**" : 1 },{})
+----
+====
+
+The `wildcardProjection` can be used to specify keys to in-/exclude in the index.
+
+.Wildcard index with `wildcardProjection`
+====
+[source,java]
+----
+@Document
+@WildcardIndexed(wildcardProjection = "{ 'userMetadata.age' : 0 }")
+public class User {
+    private @Id String id;
+    private UserMetadata userMetadata;
+}
+----
+[source,javascript]
+----
+db.user.createIndex(
+  { "$**" : 1 },
+  { "wildcardProjection" :
+    { "userMetadata.age" : 0 }
+  }
+)
+----
+====
+
+Wildcard indexes can also be expressed by adding the annotation directly to the field.
+Please note that `wildcardProjection` is not allowed on nested paths.
+
+.Wildcard index on property
+====
+[source,java]
+----
+@Document
+public class User {
+    private @Id String id;
+
+    @WildcardIndexed
+    private UserMetadata userMetadata;
+}
+----
+[source,javascript]
+----
+db.user.createIndex({ "userMetadata.$**" : 1 }, {})
+----
+====
+
 [[mapping-usage-indexes.text-index]]
 === Text Indexes