DATAMONGO-1608 - Polishing.

Throw an IllegalArgumentException when trying to create a query using 'null' as an argument for queries resulting in a $regex query operator.

Original Pull Request: #439

Author: christophstrobl

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

@@ -298,9 +298,7 @@ private Criteria createLikeRegexCriteriaOrThrow(Part part, MongoPersistentProper
 					criteria = criteria.not();
 				}
 
-				Object next = parameters.next();
-
-				return addAppropriateLikeRegexTo(criteria, part, next != null ? next.toString() : "");
+				return addAppropriateLikeRegexTo(criteria, part, parameters.next());
 
 			case NEVER:
 				// intentional no-op
@@ -328,7 +326,7 @@ private Criteria createContainingCriteria(Part part, MongoPersistentProperty pro
 			return criteria.in(nextAsArray(parameters));
 		}
 
-		return addAppropriateLikeRegexTo(criteria, part, parameters.next().toString());
+		return addAppropriateLikeRegexTo(criteria, part, parameters.next());
 	}
 
 	/**
@@ -339,9 +337,15 @@ private Criteria createContainingCriteria(Part part, MongoPersistentProperty pro
 	 * @param value
 	 * @return the criteria extended with the regex.
 	 */
-	private Criteria addAppropriateLikeRegexTo(Criteria criteria, Part part, String value) {
+	private Criteria addAppropriateLikeRegexTo(Criteria criteria, Part part, Object value) {
+
+		if (value == null) {
+
+			throw new IllegalArgumentException(String.format(
+					"Argument for creating $regex pattern for property '%s' must not be null!", part.getProperty().getSegment()));
+		}
 
-		return criteria.regex(toLikeRegex(value, part), toRegexOptions(part));
+		return criteria.regex(toLikeRegex(value.toString(), part), toRegexOptions(part));
 	}
 
 	/**

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

@@ -30,7 +30,9 @@
 import org.hamcrest.Matchers;
 import org.junit.Before;
 import org.junit.Ignore;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.dao.DuplicateKeyException;
@@ -72,6 +74,8 @@
 @RunWith(SpringJUnit4ClassRunner.class)
 public abstract class AbstractPersonRepositoryIntegrationTests {
 
+	public @Rule ExpectedException expectedException = ExpectedException.none();
+
 	@Autowired protected PersonRepository repository;
 
 	@Autowired MongoOperations operations;
@@ -171,6 +175,18 @@ public void findsPersonsByFirstnameLike() throws Exception {
 		assertThat(result, hasItem(boyd));
 	}
 
+	/**
+	 * @see DATAMONGO-1608
+	 */
+	@Test
+	public void findByFirstnameLikeWithNull() {
+
+		expectedException.expect(IllegalArgumentException.class);
+		expectedException.expectMessage("property 'firstname'");
+
+		repository.findByFirstnameLike(null);
+	}
+
 	@Test
 	public void findsPagedPersons() throws Exception {
 
@@ -720,9 +736,10 @@ public void executesGeoPageQueryForWithPageRequestForJustOneElementEmptyPage() {
 	@Test
 	public void findByFirstNameIgnoreCaseWithNull() {
 
-		List<Person> result = repository.findByFirstnameIgnoreCase(null);
+		expectedException.expect(IllegalArgumentException.class);
+		expectedException.expectMessage("property 'firstname'");
 
-		assertThat(result.size(), is(0));
+		repository.findByFirstnameIgnoreCase(null);
 	}
 
 	/**