md fix per_batch_map issue

mindspore/dataset/engine/validators.py

@@ -501,15 +501,15 @@ def check_batch(method):
             for k, v in param_dict.get('pad_info').items():
                 check_pad_info(k, v)
 
+        if (per_batch_map is None) != (input_columns is None):
+            # These two parameters appear together.
+            raise ValueError("per_batch_map and input_columns need to be passed in together.")
+
         if input_columns is not None:
             check_columns(input_columns, "input_columns")
             if len(input_columns) != (len(ins.signature(per_batch_map).parameters) - 1):
                 raise ValueError("the signature of per_batch_map should match with input columns")
 
-        if (per_batch_map is None) != (input_columns is None):
-            # These two parameters appear together.
-            raise ValueError("per_batch_map and input_columns need to be passed in together.")
-
         if output_columns is not None:
             raise ValueError("output_columns is currently not implemented.")
 

tests/ut/python/dataset/test_batch.py

@@ -466,6 +466,16 @@ def test_batch_exception_13():
         logger.info("Got an exception in DE: {}".format(str(e)))
         assert "column_order is currently not implemented." in str(e)
 
+def test_batch_exception_14():
+    batch_size = 2
+    input_columns = ["num"]
+    data1 = ds.TFRecordDataset(DATA_DIR)
+    try:
+        _ = data1.batch(batch_size=batch_size, input_columns=input_columns)
+    except ValueError as e:
+        assert "per_batch_map and input_columns need to be passed in together." in str(e)
+
+
 if __name__ == '__main__':
     test_batch_01()
     test_batch_02()
@@ -491,4 +501,5 @@ if __name__ == '__main__':
     test_batch_exception_11()
     test_batch_exception_12()
     test_batch_exception_13()
+    test_batch_exception_14()
     logger.info('\n')