Merge pull request #38 from JoshKCarroll/wildcard-fix

Fix wildcard on empty array bug

kazaam.go

@@ -215,7 +215,9 @@ func (k *Kazaam) TransformInPlace(data []byte) ([]byte, error) {
 				buffer.Write(transformedDataList[i])
 				buffer.WriteByte(',')
 			}
-			buffer.Write(transformedDataList[len(transformedDataList)-1])
+			if len(transformedDataList) > 0 {
+				buffer.Write(transformedDataList[len(transformedDataList)-1])
+			}
 			buffer.WriteByte(']')
 			data, err = jsonparser.Set(data, buffer.Bytes(), strings.Split(*specObj.Over, ".")...)
 			if err != nil {

transform/shift_test.go

@@ -33,6 +33,22 @@ func TestShiftWithWildcard(t *testing.T) {
 	}
 }
 
+func TestShiftWithWildcardEmptySlice(t *testing.T) {
+	spec := `{"outputArray": "docs[*].data.key"}`
+	jsonIn := `{"docs": []}`
+	jsonOut := `{"outputArray":[]}`
+
+	cfg := getConfig(spec, false)
+	kazaamOut, _ := getTransformTestWrapper(Shift, cfg, jsonIn)
+
+	if kazaamOut != jsonOut {
+		t.Error("Transformed data does not match expectation.")
+		t.Log("Expected:   ", jsonOut)
+		t.Log("Actual:     ", kazaamOut)
+		t.FailNow()
+	}
+}
+
 func TestShiftWithMissingKey(t *testing.T) {
 	spec := `{"Rating": "rating.primary.missing_value","example.old": "rating.example"}`
 	jsonOut := `{"Rating":null,"example":{"old":{"value":3}}}`

transform/util.go

@@ -88,7 +88,9 @@ func getJSONRaw(data []byte, path string, pathRequired bool) ([]byte, error) {
 					buffer.Write(results[i])
 					buffer.WriteByte(',')
 				}
-				buffer.Write(results[len(results)-1])
+				if len(results) > 0 {
+					buffer.Write(results[len(results)-1])
+				}
 				buffer.WriteByte(']')
 				return buffer.Bytes(), nil
 			}