Merge pull request #1598 from ostephens/no-field-null

No field null

main/src/com/google/refine/grel/ast/FieldAccessorExpr.java

@@ -63,17 +63,17 @@ public class FieldAccessorExpr implements Evaluable {
         if (ExpressionUtils.isError(o)) {
             return o; // bubble the error up
         } else if (o == null) {
-            return new EvalError("Cannot retrieve field from null");
+            return null;
         } else if (o instanceof HasFields) {
             return ((HasFields) o).getField(_fieldName, bindings);
         } else if (o instanceof JSONObject) {
             try {
                 return ((JSONObject) o).get(_fieldName);
             } catch (JSONException e) {
-                return new EvalError("Object does not have any field, including " + _fieldName);
+                return null;
             }
         } else {
-            return new EvalError("Object does not have any field, including " + _fieldName);
+            return null;
         }
     }
 

main/tests/server/src/com/google/refine/tests/grel/GrelTests.java

@@ -99,7 +99,7 @@ public class GrelTests extends RefineTest {
     public void testEvalError() {
         String tests[] = {
 //                "1=1", // TODO: Throws NullPointerException
-                "a.value",
+                "value.datePart()",
                 };
         for (String test : tests) {
             try {
@@ -166,6 +166,26 @@ public class GrelTests extends RefineTest {
             parseEval(bindings, test);
         }
     }
+
+    @Test
+    public void testGetJsonFieldExists() throws ParsingException {
+        String test[] = { "\"[{\\\"one\\\": \\\"1\\\"}]\".parseJson()[0].one", "1" };
+        parseEval(bindings, test);
+    }
+
+    @Test
+    public void testGetJsonFieldAbsent() throws ParsingException {
+        String test =  "\"[{\\\"one\\\": \\\"1\\\"}]\".parseJson()[0].two";
+        Evaluable eval = MetaParser.parse("grel:" + test);
+        Assert.assertNull(eval.evaluate(bindings));
+    }
+
+    @Test
+    public void testGetFieldFromNull() throws ParsingException {
+        String test =  "null.value";
+        Evaluable eval = MetaParser.parse("grel:" + test);
+        Assert.assertNull(eval.evaluate(bindings));
+    }
     
     // to demonstrate bug fixing for #1204
     @Test
@@ -182,11 +202,11 @@ public class GrelTests extends RefineTest {
     }
     
     private void parseEval(Properties bindings, String[] test)
-            throws ParsingException {
+    throws ParsingException {
         Evaluable eval = MetaParser.parse("grel:" + test[0]);
         Object result = eval.evaluate(bindings);
         Assert.assertEquals(result.toString(), test[1], 
-                "Wrong result for expression: "+test[0]);
+                            "Wrong result for expression: "+test[0]);
     }
 
 }