Merge pull request #32 from sykesd/31-delegated-properties-can-cause-NPE

Reproduction test case and fix

src/org/dt/japper/MapperCodeGenerator.java

@@ -6,6 +6,7 @@
 import java.sql.SQLException;
 import java.sql.Timestamp;
 import java.sql.Types;
+import java.util.Arrays;
 import java.util.Comparator;
 import java.util.Map;
 import java.util.TreeMap;
@@ -161,7 +162,7 @@ private static <T> String buildMapMethodBody(Class<T> resultType, ResultSetMetaD
 
     for (int i = 1; i <= metaData.getColumnCount(); i++) {
       PropertyDescriptor[] path = matcher.match(metaData.getColumnLabel(i), metaData.getTableName(i), metaData.getColumnName(i));
-      if (path != null) {
+      if (path != null && isWriteablePath(path)) {
         tempCounter = buildPropertySetter(setterSource, graphGuardMap, i, metaData, path, tempCounter);
       }
     }
@@ -171,7 +172,15 @@ private static <T> String buildMapMethodBody(Class<T> resultType, ResultSetMetaD
 
     return source.toString();
   }
-
+
+  private static boolean isWriteablePath(PropertyDescriptor[] path) {
+    return Arrays.stream(path)
+            .filter(pd -> pd.getWriteMethod() == null)
+            .findFirst()
+            .map(pd -> false)
+            .orElse(true)
+            ;
+  }
 
   private static class GraphGuardComparator implements Comparator<String> {
     @Override
@@ -247,7 +256,6 @@ else if (!ps.isNullable() && !ps.isNeedsConversion()) {
     return tempCounter;
   }
 
-
   private static String getNullValue(PropertySetter ps) {
     if (ps.writeType.isPrimitive()) {
       if (ps.writeType.equals(boolean.class)) return "false";

test-src/org/dt/japper/SimpleMapTest.java

@@ -9,6 +9,7 @@
 import java.util.List;
 import java.util.Set;
 
+import org.dt.japper.testmodel.DelegatedPartModel;
 import org.dt.japper.testmodel.PartModel;
 import org.dt.japper.testmodel.PartPriceModel;
 import org.junit.BeforeClass;
@@ -239,4 +240,30 @@ public void mapPrices() throws Exception {
 
     conn.close();
   }
+
+  private static final String SQL_DELEGATED_PARTS =
+          "   SELECT part.*, part.partno delegated_id "
+        + "     FROM part"
+        + " ORDER BY partno"
+          ;
+
+  /**
+   * Test case to reproduce the bug outlined here: https://github.com/sykesd/japper/issues/31
+   * We keep this test to guard against regressions.
+   *
+   * @throws Exception
+   */
+  @Test
+  public void mapDelegatedParts() throws Exception {
+    Connection conn = testData.connect();
+
+    List<DelegatedPartModel> parts = Japper.query(conn, DelegatedPartModel.class, SQL_DELEGATED_PARTS);
+    assertEquals(3, parts.size());
+
+    DelegatedPartModel part = parts.get(0);
+    assertEquals("123456", part.getPartno());
+
+    conn.close();
+  }
+
 }

test-src/org/dt/japper/testmodel/DelegatedPartModel.java

@@ -0,0 +1,50 @@
+package org.dt.japper.testmodel;
+
+import java.math.BigDecimal;
+import java.util.Map;
+
+public class DelegatedPartModel {
+    private String delegatedId;
+
+    private PartModel part = new PartModel();
+
+    public String getDelegatedId() {
+        return delegatedId;
+    }
+
+    public void setDelegatedId(String delegatedId) {
+        this.delegatedId = delegatedId;
+    }
+
+    public String getPartno() {
+        return part.getPartno();
+    }
+
+    public void setPartno(String partno) {
+        part.setPartno(partno);
+    }
+
+    public String getDescription() {
+        return part.getDescription();
+    }
+
+    public void setDescription(String description) {
+        part.setDescription(description);
+    }
+
+    // NOTE: We deliberately leave off the partType property to ensure
+    // that an incomplete delegation does not cause an NPE
+    // See https://github.com/sykesd/japper/issues/31
+
+    public Map<String, BigDecimal> getFlexFields() {
+        return part.getFlexFields();
+    }
+
+    public void setFlexFields(Map<String, BigDecimal> flexFields) {
+        part.setFlexFields(flexFields);
+    }
+
+    public PartModel getPart() {
+        return part;
+    }
+}