Python 尝试导出tf.estimator.DNNClassifier模型时出错。我怎样才能保存这个？

我已将我的估计器创建为：

estimator = tf.estimator.DNNClassifier(
   hidden_units=[500, 100],
   feature_columns=[embedded_text_feature_column],
   n_classes=2,
   optimizer=tf.train.AdagradOptimizer(learning_rate=0.003))

并以以下方式运行培训：

estimator.train(input_fn=train_input_fn, steps = 2)

在这两个步骤之后，我想保存我的模型/估计器。我尝试了以下方法：

# NOT SURE IF THE FOLLOWING FUNCTION IS CORRECT
def serving_input_receiver_fn():
  """Build the serving inputs."""
  # The outer dimension (None) allows us to batch up inputs for
  # efficiency. However, it also means that if we want a prediction
  # for a single instance, we'll need to wrap it in an outer list.

  inputs = {"x": tf.placeholder(shape=[None, 4], dtype=tf.float32)}
  return tf.estimator.export.ServingInputReceiver(inputs, inputs)

export_dir = classifier.export_savedmodel(
  export_dir_base="/home/suhail/tensorflow-stubs/",
  serving_input_receiver_fn=serving_input_receiver_fn)

但这会抛出一个错误，即：

如果功能字典中没有功能句子

。我训练了这个模特

我做错了什么