title: Tensorflow : FixedLenFeature Number of bytes values != expected
body: <p>I try to load examples from a tfrecords file. I have a reader function like :</p>
  
  <pre><code>def read_record(filename_queue):
      reader = tf.TFRecordReader()
  
      key, record_string  = reader.read(filename_queue)
  
  
      features = {
      "feature": tf.FixedLenFeature([], dtype=tf.string),
      }
  
  
      ex_dict = tf.parse_single_example(record_string, features)
  
      ex_feature = tf.decode_raw(ex_dict["feature"], tf.float32)
  
      return ex_feature
  </code></pre>
  
  <p>I've just followed <a href="https://github.com/tensorflow/tensorflow/blob/master/tensorflow/examples/how_tos/reading_data/fully_connected_reader.py" rel="nofollow noreferrer">https://github.com/tensorflow/tensorflow/blob/master/tensorflow/examples/how_tos/reading_data/fully_connected_reader.py</a></p>
  
  <p>But then </p>
  
  <pre><code>example_features = read_record(filename_queue)
  values = sess.run({"features":example_features})
  </code></pre>
  
  <p>stops with the following error :</p>
  
  <blockquote>
    <p>InvalidArgumentError: Name: , Key: feature, Index: 0.  Number of bytes values != expected.  Values size: 4096 but output shape: []
    Caused by op u'ParseSingleExample/ParseExample/ParseExample'</p>
  </blockquote>
  
  <p>What is wrong (I know I can mention the actual size but I don't want this) ?</p>