owfeatureconstructor: Always use Values for TimeVariables

Author: ales-erjavec

Orange/widgets/data/owfeatureconstructor.py

@@ -1213,6 +1213,8 @@ def extract_column(self, table: Table, var: Variable):
             idx = data.astype(int)
             idx[~np.isfinite(data)] = len(values) - 1
             return values[idx].tolist()
+        elif var.is_time:  # time always needs Values due to str(val) formatting
+            return Value._as_values(var, data.tolist())  # pylint: disable=protected-access
         elif not self.use_values:
             return data.tolist()
         else:

Orange/widgets/data/tests/test_owfeatureconstructor.py

@@ -305,6 +305,12 @@ def test_missing_variable(self):
         self.assertTrue(np.all(np.isnan(r)))
         self.assertTrue(np.isnan(f(data2[0])))
 
+    def test_time_str(self):
+        data = Table.from_numpy(Domain([TimeVariable("T", have_date=True)]), [[0], [0]])
+        f = FeatureFunc("str(T)", [("T", data.domain[0])])
+        c = f(data)
+        self.assertEqual(c, ["1970-01-01", "1970-01-01"])
+
     def test_invalid_expression_variable(self):
         iris = Table("iris")
         f = FeatureFunc("1 / petal_length",