DATACMNS-1007 - Added IsEmpty and IsNotEmpty keywords to query parser.

The query derivation mechanism now detects IsEmpty and NotIsEmpty as keywords and exposes them in the PartTree.

Original pull request: #203.

Author: BigMichi1

src/main/asciidoc/repository-query-keywords-reference.adoc

@@ -22,6 +22,8 @@ The following table lists the keywords generally supported by the Spring Data re
 |`GREATER_THAN_EQUALS`|`GreaterThanEqual`, `IsGreaterThanEqual`
 |`IN`|`In`, `IsIn`
 |`IS`|`Is`, `Equals`, (or no keyword)
+|`IS_EMPTY`|`IsEmpty`, `Empty`
+|`IS_NOT_EMPTY`|`IsNotEmpty`, `NotEmpty`
 |`IS_NOT_NULL`|`NotNull`, `IsNotNull`
 |`IS_NULL`|`Null`, `IsNull`
 |`LESS_THAN`|`LessThan`, `IsLessThan`

src/main/java/org/springframework/data/repository/query/parser/Part.java

@@ -34,6 +34,7 @@
  * 
  * @author Oliver Gierke
  * @author Martin Baumgartner
+ * @author Michael Cramer
  */
 public class Part {
 
@@ -188,13 +189,15 @@ public static enum Type {
 				"IsNotContaining", "NotContaining", "NotContains"), CONTAINING("IsContaining", "Containing", "Contains"), NOT_IN(
 				"IsNotIn", "NotIn"), IN("IsIn", "In"), NEAR("IsNear", "Near"), WITHIN("IsWithin", "Within"), REGEX(
 				"MatchesRegex", "Matches", "Regex"), EXISTS(0, "Exists"), TRUE(0, "IsTrue", "True"), FALSE(0, "IsFalse",
-				"False"), NEGATING_SIMPLE_PROPERTY("IsNot", "Not"), SIMPLE_PROPERTY("Is", "Equals");
+				"False"), NEGATING_SIMPLE_PROPERTY("IsNot", "Not"), SIMPLE_PROPERTY("Is", "Equals"), IS_NOT_EMPTY(0, "IsNotEmpty",
+				"NotEmpty"), IS_EMPTY(0, "IsEmpty", "Empty");
 
 		// Need to list them again explicitly as the order is important
 		// (esp. for IS_NULL, IS_NOT_NULL)
 		private static final List<Part.Type> ALL = Arrays.asList(IS_NOT_NULL, IS_NULL, BETWEEN, LESS_THAN, LESS_THAN_EQUAL,
-				GREATER_THAN, GREATER_THAN_EQUAL, BEFORE, AFTER, NOT_LIKE, LIKE, STARTING_WITH, ENDING_WITH, NOT_CONTAINING,
-				CONTAINING, NOT_IN, IN, NEAR, WITHIN, REGEX, EXISTS, TRUE, FALSE, NEGATING_SIMPLE_PROPERTY, SIMPLE_PROPERTY);
+				GREATER_THAN, GREATER_THAN_EQUAL, BEFORE, AFTER, NOT_LIKE, LIKE, STARTING_WITH, ENDING_WITH, IS_NOT_EMPTY,
+				IS_EMPTY, NOT_CONTAINING, CONTAINING, NOT_IN, IN, NEAR, WITHIN, REGEX, EXISTS, TRUE, FALSE,
+				NEGATING_SIMPLE_PROPERTY, SIMPLE_PROPERTY);
 
 		public static final Collection<String> ALL_KEYWORDS;
 

src/test/java/org/springframework/data/repository/query/parser/PartTreeUnitTests.java

@@ -45,6 +45,7 @@
  * @author Martin Baumgartner
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Michael Cramer
  */
 public class PartTreeUnitTests {
 
@@ -221,6 +222,16 @@ public void returnsAllPartsOfType() {
 		assertThat(parts, is(hasSize(1)));
 	}
 
+	@Test // DATACMNS-1007
+	public void parsesEmptyKeywordCorrectly() {
+		assertType(asList("friendsIsEmpty", "friendsEmpty"), IS_EMPTY, "friends", 0, false);
+	}
+
+	@Test // DATACMNS-1007
+	public void parsesNotEmptyKeywordCorrectly() {
+		assertType(asList("friendsIsNotEmpty", "friendsNotEmpty"), IS_NOT_EMPTY, "friends", 0, false);
+	}
+
 	@Test // DATACMNS-94
 	public void parsesExistsKeywordCorrectly() {
 		assertType(asList("lastnameExists"), EXISTS, "lastname", 0, false);
@@ -651,6 +662,7 @@ class User {
 		double[] location;
 		boolean active;
 		Date birthday;
+		List<User> friends;
 	}
 
 	class Organization {