RESOLVED - issue BATCH-1361: PassThroughFieldExtractor does not handle Maps

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/transform/PassThroughFieldExtractor.java

@@ -16,6 +16,7 @@
 package org.springframework.batch.item.file.transform;
 
 import java.util.Collection;
+import java.util.Map;
 
 /**
  * {@link FieldExtractor} that just returns the original item. If the item is an
@@ -28,6 +29,20 @@ import java.util.Collection;
 public class PassThroughFieldExtractor<T> implements FieldExtractor<T> {
 
 	/**
+	 * Get an array of fields as close as possible to the input. The result
+	 * depends on the type of the input:
+	 * <ul>
+	 * <li>A {@link FieldSet} or array will be returned as is</li>
+	 * <li>For a Collection the <code>toArray()</code> method will be used</li>
+	 * <li>For a Map the <code>values()</code> will be returned as an array</li>
+	 * <li>Otherwise it is wrapped in a single element array.</li>
+	 * </ul>
+	 * Note that no attempt is made to sort the values, so passing in an
+	 * unordered collection or map is probably a bad idea. Spring often gives
+	 * you an ordered Map (e.g. if extracting data from a generic query using
+	 * JDBC), so check the documentation for whatever is being used to generate
+	 * the input.
+	 * 
 	 * @param item the object to convert
 	 * @return an array of objects as close as possible to the original item
 	 */
@@ -41,6 +56,10 @@ public class PassThroughFieldExtractor<T> implements FieldExtractor<T> {
 			return ((Collection<?>) item).toArray();
 		}
 
+		if (item instanceof Map<?, ?>) {
+			return ((Map<?, ?>) item).values().toArray();
+		}
+
 		if (item instanceof FieldSet) {
 			return ((FieldSet) item).getValues();
 		}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/transform/PassThroughFieldExtractorTests.java

@@ -18,7 +18,9 @@ package org.springframework.batch.item.file.transform;
 import static junit.framework.Assert.assertTrue;
 
 import java.util.Arrays;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.Test;
 
@@ -55,4 +57,17 @@ public class PassThroughFieldExtractorTests {
 		Object[] result = extractor.extract(Arrays.asList("a", "b", null, "d"));
 		assertTrue(Arrays.equals(new Object[] { "a", "b", null, "d" }, result));
 	}
+
+	@Test
+	public void testExtractMap() {
+		PassThroughFieldExtractor<Map<String, String>> extractor = new PassThroughFieldExtractor<Map<String, String>>();
+		Map<String, String> map = new LinkedHashMap<String, String>();
+		map.put("A", "a");
+		map.put("B", "b");
+		map.put("C", null);
+		map.put("D", "d");
+		Object[] result = extractor.extract(map);
+		assertTrue(Arrays.equals(new Object[] { "a", "b", null, "d" }, result));
+	}
+
 }