DATACMNS-1551 - SortHandlerMethodArgumentResolver now drops dot-only property segments.

If plain dots were submitted as elements in a Sort expression to be parsed by SortHandlerMethodArgumentResolver, those dots would be considered a property of the sort expression, which is of course wrong. We now drop property candidates solely consisting of dots and whitespace.

src/main/java/org/springframework/data/web/SortHandlerMethodArgumentResolver.java

@@ -213,16 +213,25 @@ public class SortHandlerMethodArgumentResolver implements SortArgumentResolver {
 				continue;
 			}
 
-			String[] elements = part.split(delimiter);
-			Direction direction = elements.length == 0 ? null : Direction.fromStringOrNull(elements[elements.length - 1]);
+			List<String> elements = new ArrayList<String>();
 
-			for (int i = 0; i < elements.length; i++) {
+			for (String candidate : part.split(delimiter)) {
+				if (StringUtils.hasText(candidate.replace(".", ""))) {
+					elements.add(candidate);
+				}
+			}
+
+			int numberOfElements = elements.size();
+			Direction direction = numberOfElements == 0 ? null
+					: Direction.fromStringOrNull(elements.get(numberOfElements - 1));
+
+			for (int i = 0; i < numberOfElements; i++) {
 
-				if (i == elements.length - 1 && direction != null) {
+				if (i == numberOfElements - 1 && direction != null) {
 					continue;
 				}
 
-				String property = elements[i];
+				String property = elements.get(i);
 
 				if (!StringUtils.hasText(property)) {
 					continue;

src/test/java/org/springframework/data/web/SortHandlerMethodArgumentResolverUnitTests.java

@@ -19,6 +19,8 @@ import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 import static org.springframework.data.domain.Sort.Direction.*;
 
+import java.util.Arrays;
+
 import javax.servlet.http.HttpServletRequest;
 
 import org.junit.BeforeClass;
@@ -183,6 +185,18 @@ public class SortHandlerMethodArgumentResolverUnitTests extends SortDefaultUnitT
 		assertThat(resolveSort(request, getParameterOfMethod("containeredDefault")), is(new Sort("foo", "bar")));
 	}
 
+	@Test // DATACMNS-1551
+	public void resolvesDotOnlyInputToDefault() throws Exception {
+
+		for (String source : Arrays.asList(".", ".,ASC")) {
+
+			MockHttpServletRequest request = new MockHttpServletRequest();
+			request.addParameter("sort", source);
+
+			assertThat(resolveSort(request, PARAMETER), is(nullValue()));
+		}
+	}
+
 	private static Sort resolveSort(HttpServletRequest request, MethodParameter parameter) throws Exception {
 
 		SortHandlerMethodArgumentResolver resolver = new SortHandlerMethodArgumentResolver();