tf.data.Dataset expands dim in model.fit if batch_input_shape is (None,)

[tyagi619]

I created tf.data.Dataset object with shape ({‘users’:(None,), ‘movies’:(None,)}, (None,)). If I iterate over the dataset object outside model.fit, I see that the shape is same as specified above. But inside model.fit, the input shape changes to {‘users’:(None,1), ‘movies’:(None,1)]. I am using model sub-classing.