!3912 fix numpyslice bug

Merge pull request !3912 from luoyang/son_r0.6

mindspore/ccsrc/minddata/dataset/core/tensor.cc

@@ -268,6 +268,10 @@ Status Tensor::CreateTensor(std::shared_ptr<Tensor> *ptr, py::array arr) {
   std::shared_ptr<MemoryPool> global_pool = GlobalContext::Instance()->mem_pool();
   (*ptr)->data_allocator_ = std::make_unique<Allocator<unsigned char>>(global_pool);
   int64_t byte_size = (*ptr)->SizeInBytes();
+  if (byte_size == 0) {
+    return Status::OK();
+  }
+
   RETURN_IF_NOT_OK((*ptr)->AllocateBuffer(byte_size));
 
   unsigned char *data = static_cast<unsigned char *>(arr.request().ptr);

tests/ut/python/dataset/test_dataset_numpy_slices.py

@@ -82,6 +82,16 @@ def test_numpy_slices_dict_1():
         assert data[0] == res[i][0]
         assert data[1] == res[i][1]
 
+def test_numpy_slices_dict_2():
+    logger.info("Test Dictionary empty data.")
+
+    np_data = {"a": [[]], "b": [[4]]}
+    ds = de.NumpySlicesDataset(np_data, shuffle=False)
+    res = [[], [4]]
+
+    for _, data in enumerate(ds):
+        np.testing.assert_array_almost_equal(data[0], np.array(res[0]))
+        np.testing.assert_array_almost_equal(data[1], np.array(res[1]))
 
 def test_numpy_slices_tuple_1():
     logger.info("Test slicing a list of tuple.")