Introduce explicit index field matching methods.

Closes #5187

Signed-off-by: dragonfsky <dragonfsky@gmail.com>

Author: DragonFSKY

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

@@ -24,6 +24,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 import org.bson.Document;
@@ -41,6 +42,7 @@
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author dragonfsky
  */
 public class IndexInfo {
 
@@ -182,16 +184,75 @@ public List<IndexField> getIndexFields() {
 	}
 
 	/**
-	 * Returns whether the index is covering exactly the fields given independently of the order.
+	 * Returns whether the index contains all fields given independently of their position.
 	 *
 	 * @param keys must not be {@literal null}.
 	 * @return
+	 * @since 5.1
 	 */
+	public boolean containsAllFields(Collection<String> keys) {
+
+		Assert.notNull(keys, "Collection of keys must not be null");
+
+		return getIndexFieldKeys().containsAll(keys);
+	}
+
+	/**
+	 * Returns whether the index contains all fields given independently of their position.
+	 *
+	 * @param keys must not be {@literal null}.
+	 * @return
+	 * @deprecated since 5.1. Use {@link #containsAllFields(Collection)}, {@link #isIndexForFieldsExactly(Collection)}, or
+	 *             {@link #coversFields(Collection)} to express the intended index field matching semantics.
+	 */
+	@Deprecated(since = "5.1")
 	public boolean isIndexForFields(Collection<String> keys) {
+		return containsAllFields(keys);
+	}
+
+	/**
+	 * Returns whether the index matches exactly the fields given independently of the order.
+	 *
+	 * @param keys must not be {@literal null}.
+	 * @return
+	 * @since 5.1
+	 */
+	public boolean isIndexForFieldsExactly(Collection<String> keys) {
 
 		Assert.notNull(keys, "Collection of keys must not be null");
 
-		return this.indexFields.stream().map(IndexField::getKey).collect(Collectors.toSet()).containsAll(keys);
+		Set<String> indexFieldKeys = getIndexFieldKeys();
+		Set<String> keysToCheck = keys.stream().collect(Collectors.toSet());
+
+		return indexFieldKeys.size() == keysToCheck.size() && indexFieldKeys.containsAll(keysToCheck);
+	}
+
+	/**
+	 * Returns whether the index can efficiently support a query using the given fields according to MongoDB compound
+	 * index prefix rules.
+	 *
+	 * @param keys must not be {@literal null}.
+	 * @return
+	 * @since 5.1
+	 */
+	public boolean coversFields(Collection<String> keys) {
+
+		Assert.notNull(keys, "Collection of keys must not be null");
+
+		Set<String> keysToCheck = keys.stream().collect(Collectors.toSet());
+
+		if (keysToCheck.size() > indexFields.size()) {
+			return false;
+		}
+
+		Set<String> indexFieldPrefix = indexFields.stream().limit(keysToCheck.size()).map(IndexField::getKey)
+				.collect(Collectors.toSet());
+
+		return indexFieldPrefix.containsAll(keysToCheck);
+	}
+
+	private Set<String> getIndexFieldKeys() {
+		return this.indexFields.stream().map(IndexField::getKey).collect(Collectors.toSet());
 	}
 
 	public String getName() {

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

@@ -30,6 +30,7 @@
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Stefan Tirea
+ * @author dragonfsky
  */
 class IndexInfoUnitTests {
 
@@ -50,14 +51,52 @@ class IndexInfoUnitTests {
 			   }
 			""";
 
-	@Test
-	void isIndexForFieldsCorrectly() {
+	@Test // GH-5187
+	@SuppressWarnings("deprecation")
+	void isIndexForFieldsRetainsContainsAllBehavior() {
 
 		IndexField fooField = IndexField.create("foo", Direction.ASC);
 		IndexField barField = IndexField.create("bar", Direction.DESC);
 
 		IndexInfo info = new IndexInfo(Arrays.asList(fooField, barField), "myIndex", false, false, "");
 		assertThat(info.isIndexForFields(Arrays.asList("foo", "bar"))).isTrue();
+		assertThat(info.isIndexForFields(Arrays.asList("foo"))).isTrue();
+	}
+
+	@Test // GH-5187
+	void containsAllFieldsReturnsTrueForFieldSubset() {
+
+		IndexInfo info = new IndexInfo(Arrays.asList(IndexField.create("foo", Direction.ASC),
+				IndexField.create("bar", Direction.DESC)), "myIndex", false, false, "");
+
+		assertThat(info.containsAllFields(Arrays.asList("foo"))).isTrue();
+		assertThat(info.containsAllFields(Arrays.asList("bar", "foo"))).isTrue();
+		assertThat(info.containsAllFields(Arrays.asList("foo", "baz"))).isFalse();
+	}
+
+	@Test // GH-5187
+	void isIndexForFieldsExactlyRequiresSameFields() {
+
+		IndexInfo info = new IndexInfo(Arrays.asList(IndexField.create("foo", Direction.ASC),
+				IndexField.create("bar", Direction.DESC)), "myIndex", false, false, "");
+
+		assertThat(info.isIndexForFieldsExactly(Arrays.asList("foo", "bar"))).isTrue();
+		assertThat(info.isIndexForFieldsExactly(Arrays.asList("bar", "foo"))).isTrue();
+		assertThat(info.isIndexForFieldsExactly(Arrays.asList("foo"))).isFalse();
+		assertThat(info.isIndexForFieldsExactly(Arrays.asList("foo", "bar", "baz"))).isFalse();
+	}
+
+	@Test // GH-5187
+	void coversFieldsOnlyMatchesIndexPrefixes() {
+
+		IndexInfo info = new IndexInfo(Arrays.asList(IndexField.create("foo", Direction.ASC),
+				IndexField.create("bar", Direction.DESC), IndexField.create("baz", Direction.ASC)), "myIndex", false,
+				false, "");
+
+		assertThat(info.coversFields(Arrays.asList("foo"))).isTrue();
+		assertThat(info.coversFields(Arrays.asList("bar", "foo"))).isTrue();
+		assertThat(info.coversFields(Arrays.asList("bar"))).isFalse();
+		assertThat(info.coversFields(Arrays.asList("foo", "baz"))).isFalse();
 	}
 
 	@Test // DATAMONGO-2170

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

@@ -41,6 +41,7 @@
  * Integration test for index creation for query methods.
  *
  * @author Oliver Gierke
+ * @author dragonfsky
  */
 @RunWith(SpringRunner.class)
 @ContextConfiguration
@@ -84,7 +85,7 @@ public void testname() {
 	private static void assertHasIndexForField(List<IndexInfo> indexInfo, String... fields) {
 
 		for (IndexInfo info : indexInfo) {
-			if (info.isIndexForFields(Arrays.asList(fields))) {
+			if (info.containsAllFields(Arrays.asList(fields))) {
 				return;
 			}
 		}