Polishing.

Reformat code. Tweak javadoc. Reject wildcard projection usage on properties with a MappingException. Omit wildcard projections when declared on document types that are used as subdocument.

See #3225
Original pull request: #3671.

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

@@ -115,7 +115,7 @@ private static Converter<IndexDefinition, IndexOptions> getIndexDefinitionIndexO
 				ops = ops.collation(fromDocument(indexOptions.get("collation", Document.class)));
 			}
 
-			if(indexOptions.containsKey("wildcardProjection")) {
+			if (indexOptions.containsKey("wildcardProjection")) {
 				ops.wildcardProjection(indexOptions.get("wildcardProjection", Document.class));
 			}
 

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

@@ -29,7 +29,17 @@
 public final class IndexField {
 
 	enum Type {
-		GEO, TEXT, DEFAULT, HASH, WILDCARD;
+		GEO, TEXT, DEFAULT,
+
+		/**
+		 * @since 2.2
+		 */
+		HASH,
+
+		/**
+		 * @since 3.3
+		 */
+		WILDCARD;
 	}
 
 	private final String key;
@@ -78,7 +88,8 @@ static IndexField hashed(String key) {
 	}
 
 	/**
-	 * Creates a {@literal wildcard} {@link IndexField} for the given key.
+	 * Creates a {@literal wildcard} {@link IndexField} for the given key. The {@code key} must follow the
+	 * {@code fieldName.$**} notation.
 	 *
 	 * @param key must not be {@literal null} or empty.
 	 * @return new instance of {@link IndexField}.

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

@@ -100,7 +100,7 @@ public static IndexInfo indexInfoOf(Document sourceDocument) {
 
 				if (ObjectUtils.nullSafeEquals("hashed", value)) {
 					indexFields.add(IndexField.hashed(key));
-				} else if (key.contains("$**")) {
+				} else if (key.endsWith("$**")) {
 					indexFields.add(IndexField.wildcard(key));
 				} else {
 

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

@@ -119,6 +119,8 @@ public List<IndexDefinitionHolder> resolveIndexForEntity(MongoPersistentEntity<?
 		Assert.notNull(document, () -> String
 				.format("Entity %s is not a collection root. Make sure to annotate it with @Document!", root.getName()));
 
+		verifyWildcardIndexedProjection(root);
+
 		List<IndexDefinitionHolder> indexInformation = new ArrayList<>();
 		String collection = root.getCollection();
 		indexInformation.addAll(potentiallyCreateCompoundIndexDefinitions("", collection, root));
@@ -133,6 +135,24 @@ public List<IndexDefinitionHolder> resolveIndexForEntity(MongoPersistentEntity<?
 		return indexInformation;
 	}
 
+	private void verifyWildcardIndexedProjection(MongoPersistentEntity<?> entity) {
+
+		entity.doWithAll(it -> {
+
+			if (it.isAnnotationPresent(WildcardIndexed.class)) {
+
+				WildcardIndexed indexed = it.getRequiredAnnotation(WildcardIndexed.class);
+
+				if (!ObjectUtils.isEmpty(indexed.wildcardProjection())) {
+
+					throw new MappingException(String.format(
+							"WildcardIndexed.wildcardProjection cannot be used on nested paths. Offending property: %s.%s",
+							entity.getName(), it.getName()));
+				}
+			}
+		});
+	}
+
 	private void potentiallyAddIndexForProperty(MongoPersistentEntity<?> root, MongoPersistentProperty persistentProperty,
 			List<IndexDefinitionHolder> indexes, CycleGuard guard) {
 
@@ -257,7 +277,7 @@ private List<IndexDefinitionHolder> potentiallyCreateCompoundIndexDefinitions(St
 	private List<IndexDefinitionHolder> potentiallyCreateWildcardIndexDefinitions(String dotPath, String collection,
 			MongoPersistentEntity<?> entity) {
 
-		if (entity.findAnnotation(WildcardIndexed.class) == null) {
+		if (!entity.isAnnotationPresent(WildcardIndexed.class)) {
 			return Collections.emptyList();
 		}
 
@@ -429,7 +449,7 @@ protected IndexDefinitionHolder createWildcardIndexDefinition(String dotPath, St
 
 		WildcardIndex indexDefinition = new WildcardIndex(dotPath);
 
-		if (StringUtils.hasText(index.wildcardProjection())) {
+		if (StringUtils.hasText(index.wildcardProjection()) && ObjectUtils.isEmpty(dotPath)) {
 			indexDefinition.wildcardProjection(evaluateWildcardProjection(index.wildcardProjection(), entity));
 		}
 

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

@@ -51,7 +51,7 @@
 public class WildcardIndex extends Index {
 
 	private @Nullable String fieldName;
-	private Map<String, Object> wildcardProjection = new LinkedHashMap<>();
+	private final Map<String, Object> wildcardProjection = new LinkedHashMap<>();
 
 	/**
 	 * Create a new instance of {@link WildcardIndex} using {@code $**}.
@@ -97,7 +97,7 @@ public WildcardIndex named(String name) {
 	/**
 	 * Unique option is not supported.
 	 *
-	 * @throws UnsupportedOperationException
+	 * @throws UnsupportedOperationException not supported for wildcard indexes.
 	 */
 	@Override
 	public Index unique() {
@@ -107,7 +107,7 @@ public Index unique() {
 	/**
 	 * ttl option is not supported.
 	 *
-	 * @throws UnsupportedOperationException
+	 * @throws UnsupportedOperationException not supported for wildcard indexes.
 	 */
 	@Override
 	public Index expire(long seconds) {
@@ -117,7 +117,7 @@ public Index expire(long seconds) {
 	/**
 	 * ttl option is not supported.
 	 *
-	 * @throws UnsupportedOperationException
+	 * @throws UnsupportedOperationException not supported for wildcard indexes.
 	 */
 	@Override
 	public Index expire(long value, TimeUnit timeUnit) {
@@ -127,7 +127,7 @@ public Index expire(long value, TimeUnit timeUnit) {
 	/**
 	 * ttl option is not supported.
 	 *
-	 * @throws UnsupportedOperationException
+	 * @throws UnsupportedOperationException not supported for wildcard indexes.
 	 */
 	@Override
 	public Index expire(Duration duration) {

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

@@ -38,7 +38,7 @@
  *
  * db.product.createIndex({ "$**" : 1 } , {})
  * </pre>
- * 
+ *
  * {@literal wildcardProjection} can be used to specify keys to in-/exclude in the index.
  *
  * <pre class="code">
@@ -65,7 +65,7 @@
  * <pre class="code">
  * &#64;Document
  * public class User {
- * 
+ *
  *     private &#64;Id String id;
  *
  *     &#64;WildcardIndexed
@@ -89,9 +89,9 @@
 	 * 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
+	 * provided name will be prefixed with the path leading to the entity.
+	 *
+	 * @return empty by default.
 	 */
 	String name() default "";
 
@@ -115,8 +115,8 @@
 	/**
 	 * 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.
-	 * 
+	 * <strong>NOTE: </strong>Can only be applied on root level documents.
+	 *
 	 * @return empty by default.
 	 */
 	String wildcardProjection() default "";

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

@@ -32,10 +32,12 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.Suite;
 import org.junit.runners.Suite.SuiteClasses;
+
 import org.springframework.core.annotation.AliasFor;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.geo.Point;
+import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mongodb.core.DocumentTestUtils;
 import org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.IndexDefinitionHolder;
 import org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolverUnitTests.CompoundIndexResolutionTests;
@@ -1333,6 +1335,20 @@ public void resolvesWildcardOnRoot() {
 			assertThat(indices).hasSize(1);
 			assertThat(indices.get(0)).satisfies(it -> {
 				assertThat(it.getIndexKeys()).containsEntry("$**", 1);
+				assertThat(it.getIndexOptions()).isEmpty();
+			});
+		}
+
+		@Test // GH-3225
+		public void resolvesWildcardWithProjectionOnRoot() {
+
+			List<IndexDefinitionHolder> indices = prepareMappingContextAndResolveIndexForType(
+					WithWildCardIndexHavingProjectionOnEntity.class);
+			assertThat(indices).hasSize(1);
+			assertThat(indices.get(0)).satisfies(it -> {
+				assertThat(it.getIndexKeys()).containsEntry("$**", 1);
+				assertThat(it.getIndexOptions()).containsEntry("wildcardProjection",
+						org.bson.Document.parse("{'_id' : 1, 'value' : 0}"));
 			});
 		}
 
@@ -1365,6 +1381,15 @@ public void resolvesWildcardTypeOfNestedProperty() {
 			assertThat(indices).hasSize(1);
 			assertThat(indices.get(0)).satisfies(it -> {
 				assertThat(it.getIndexKeys()).containsEntry("value.$**", 1);
+				assertThat(it.getIndexOptions()).hasSize(1).containsKey("name");
+			});
+		}
+
+		@Test // GH-3225
+		public void rejectsWildcardProjectionOnNestedPaths() {
+
+			assertThatExceptionOfType(MappingException.class).isThrownBy(() -> {
+				prepareMappingContextAndResolveIndexForType(WildcardIndexedProjectionOnNestedPath.class);
 			});
 		}
 
@@ -1647,10 +1672,16 @@ class WithWildCardIndexOnProperty {
 
 		}
 
+		@Document
+		class WildcardIndexedProjectionOnNestedPath {
+
+			@WildcardIndexed(wildcardProjection = "{}") String foo;
+		}
+
 		@Document
 		class WithWildCardOnEntityOfNested {
 
-			WithWildCardIndexOnEntity value;
+			WithWildCardIndexHavingProjectionOnEntity value;
 
 		}
 

src/main/asciidoc/new-features.adoc

@@ -6,6 +6,7 @@
 
 * Extended support for <<mapping-usage.document-references, referencing>> entities.
 * Include/exclude `null` properties on write to `Document` through `@Field(write=…)`.
+* Support for <<mapping-usage-indexes.wildcard-index>>.
 
 [[new-features.3.2]]
 == What's New in Spring Data MongoDB 3.2

src/main/asciidoc/reference/mapping.adoc

@@ -782,9 +782,9 @@ db.user.createIndex({ "userMetadata.$**" : 1 }, {})
 ----
 ====
 
-The `@WildcardIndex` annotation allows a declarative index setup an can be added on either a type or property.
+The `@WildcardIndex` annotation allows a declarative index setup that can used either with a document 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
+If placed on a type that is a root level domain entity (one annotated with `@Document`) , the index resolver will create a
 wildcard index for it.
 
 .Wildcard index on domain type
@@ -794,7 +794,7 @@ wildcard index for it.
 @Document
 @WildcardIndexed
 public class Product {
-    ...
+	// …
 }
 ----
 [source,javascript]
@@ -828,7 +828,8 @@ db.user.createIndex(
 ====
 
 Wildcard indexes can also be expressed by adding the annotation directly to the field.
-Please note that `wildcardProjection` is not allowed on nested paths.
+Please note that `wildcardProjection` is not allowed on nested paths such as properties.
+Projections on types annotated with `@WildcardIndexed` are omitted during index creation.
 
 .Wildcard index on property
 ====