Improve error message for indexed property

Author: harawata

src/main/java/org/apache/ibatis/reflection/wrapper/BaseWrapper.java

@@ -43,6 +43,10 @@ protected Object resolveCollection(PropertyTokenizer prop, Object object) {
   }
 
   protected Object getCollectionValue(PropertyTokenizer prop, Object collection) {
+    if (collection == null) {
+      throw new ReflectionException("Cannot get the value '" + prop.getIndexedName() + "' because the property '"
+          + prop.getName() + "' is null.");
+    }
     if (collection instanceof Map) {
       return ((Map) collection).get(prop.getIndex());
     }
@@ -68,8 +72,8 @@ protected Object getCollectionValue(PropertyTokenizer prop, Object collection) {
     } else if (collection instanceof short[]) {
       return ((short[]) collection)[i];
     } else {
-      throw new ReflectionException(
-          "The '" + prop.getName() + "' property of " + collection + " is not a List or Array.");
+      throw new ReflectionException("Cannot get the value '" + prop.getIndexedName() + "' because the property '"
+          + prop.getName() + "' is not Map, List or Array.");
     }
   }
 

src/test/java/org/apache/ibatis/reflection/wrapper/BeanWrapperTest.java

@@ -59,8 +59,7 @@ void assertBasicOperations() {
       metaObj.getValue("bean2List[0]");
       fail();
     } catch (ReflectionException e) {
-      // TODO: more accurate message
-      assertEquals("The 'bean2List' property of null is not a List or Array.", e.getMessage());
+      assertEquals("Cannot get the value 'bean2List[0]' because the property 'bean2List' is null.", e.getMessage());
     }
     assertTrue(metaObj.hasSetter("bean2List[0]"));
 
@@ -77,6 +76,13 @@ void assertBasicOperations() {
 
     metaObj.setValue("attrVal", "value");
     assertEquals("value", bean.getAttrVal());
+    try {
+      metaObj.getValue("attrVal[0]");
+      fail();
+    } catch (ReflectionException e) {
+      assertEquals("Cannot get the value 'attrVal[0]' because the property 'attrVal' is not Map, List or Array.",
+          e.getMessage());
+    }
 
     metaObj.setValue("bean2List[1].name", "new name 1");
     assertEquals("new name 1", bean.getBean2List().get(1).getName());
@@ -144,7 +150,6 @@ void assertBasicOperations() {
     } catch (UnsupportedOperationException e) {
       // pass
     }
-
   }
 
   static class Bean1 {