ParquetDataset return a error shape .

[zhaozheng09]

error log:

Traceback (most recent call last):
  File "train.py", line 832, in <module>
    main()
  File "train.py", line 544, in main
    iterator = tf.data.Iterator.from_structure(train_dataset.output_types,
AttributeError: 'PrefetchDataset' object has no attribute 'output_types'

modify :/root/DeepRec/modelzoo/dlrm

diff --git a/modelzoo/dlrm/train.py b/modelzoo/dlrm/train.py
index 1cd0e7915e..5fbc5ee4f2 100644
--- a/modelzoo/dlrm/train.py
+++ b/modelzoo/dlrm/train.py
@@ -24,6 +24,7 @@ from tensorflow.python.client import timeline
 import json

 from tensorflow.python.ops import partitioned_variables
+from tensorflow.python.data.experimental.ops import parquet_dataset_ops

 # Set to INFO for tracking training, default is WARN. ERROR for least messages
 tf.logging.set_verbosity(tf.logging.INFO)
@@ -300,6 +301,22 @@ def build_model_input(filename, batch_size, num_epochs):
         features = all_columns
         return features, labels

+    def parse_parquet(value):
+        cont_defaults = [[0.0] for i in range(1, 14)]
+        cate_defaults = [[' '] for i in range(1, 27)]
+        label_defaults = [[0]]
+        column_headers = TRAIN_DATA_COLUMNS
+        record_defaults = label_defaults + cont_defaults + cate_defaults
+        columns = value
+        vs = []
+        for k,v in columns.items():
+            vs.append(v)
+        all_columns = collections.OrderedDict(zip(column_headers, vs))
+        labels = all_columns.pop(LABEL_COLUMN[0])
+        features = all_columns
+        return features, labels
+
+
     '''Work Queue Feature'''
     if args.workqueue and not args.tf:
         from tensorflow.python.ops.work_queue import WorkQueue
@@ -311,12 +328,8 @@ def build_model_input(filename, batch_size, num_epochs):

[JackMoriarty]

ParquetDataset usage examples have been added to DeepRec modelzoo, please refer to PR#684.