!5227 dataset_return_single_value

Merge pull request !5227 from lijiaqi/dataset_return_single_value

mindspore/train/model.py

@@ -37,6 +37,16 @@ from .dataset_helper import DatasetHelper
 from . import amp
 
 
+def _transfer_tensor_to_tuple(inputs):
+    """
+    If the input is a tensor, convert it to a tuple. If not, the output is unchanged.
+    """
+    if isinstance(inputs, Tensor):
+        return (inputs,)
+
+    return inputs
+
+
 class Model:
     """
     High-Level API for Training or Testing.
@@ -476,6 +486,7 @@ class Model:
 
             for next_element in dataset_helper:
                 len_element = len(next_element)
+                next_element = _transfer_tensor_to_tuple(next_element)
                 if self._loss_fn and len_element != 2:
                     raise ValueError("when loss_fn is not None, train_dataset should"
                                      "return two elements, but got {}".format(len_element))
@@ -630,6 +641,7 @@ class Model:
         for next_element in dataset_helper:
             cb_params.cur_step_num += 1
             list_callback.step_begin(run_context)
+            next_element = _transfer_tensor_to_tuple(next_element)
             outputs = self._eval_network(*next_element)
             cb_params.net_outputs = outputs
             list_callback.step_end(run_context)