Error on non existent field

This attempts to duplicate the datastore API: this error is non fatal, and
processing will continue. It is up to the caller to decide what to do.

wmi.go

@@ -121,7 +121,7 @@ func (e *ErrFieldMismatch) Error() string {
 var timeType = reflect.TypeOf(time.Time{})
 
 // loadEntity loads a SWbemObject into a struct pointer.
-func loadEntity(dst interface{}, src *ole.IDispatch) error {
+func loadEntity(dst interface{}, src *ole.IDispatch) (errFieldMismatch error) {
 	v := reflect.ValueOf(dst).Elem()
 	for i := 0; i < v.NumField(); i++ {
 		f := v.Field(i)
@@ -135,6 +135,11 @@ func loadEntity(dst interface{}, src *ole.IDispatch) error {
 		}
 		prop, err := oleutil.GetProperty(src, n)
 		if err != nil {
+			errFieldMismatch = &ErrFieldMismatch{
+				StructType: f.Type(),
+				FieldName:  n,
+				Reason:     "no such struct field",
+			}
 			continue
 		}
 		switch val := prop.Value(); reflect.ValueOf(val).Kind() {
@@ -195,7 +200,7 @@ func loadEntity(dst interface{}, src *ole.IDispatch) error {
 			}
 		}
 	}
-	return nil
+	return errFieldMismatch
 }
 
 type multiArgType int

wmi_test.go

@@ -9,3 +9,16 @@ func TestQuery(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestFieldMismatch(t *testing.T) {
+	type s struct {
+		Name        string
+		HandleCount uint32
+		Blah        uint32
+	}
+	var dst[]s
+	err := Query("SELECT Name, HandleCount FROM Win32_Process", &dst)
+	if err == nil || err.Error() != `wmi: cannot load field "Blah" into a "uint32": no such struct field` {
+		t.Error("Expected err field mismatch")
+	}
+}