Patching BigQuery connector in 0.7.0 release and upgrading release to 0.7.1 (#556)

* adding README document describing how to use BigQuery connector (#467)

* adding README document describing how to use BigQuery connector

* Fixing BigQuery connector package definition, and updating README.md accordingly

* More changes for BigQuery connector (#490)

* Fixing Dockerfile

* Returning dataset in a form of Dictionary from BigQuery connector

* Adding NULL fields support to BigQuery connector

* python style tweak

* more style tweaks

* Style tweaks, comming from google account

* Properly setting row_restriction in createReadSessionRequest and updating sample accordingly (#529)

* updating version 0.7.0 -> 0.7.1

* locking TF version to 1.14

* linter fix

Author: vlasenkoalexey

configure.sh

@@ -18,7 +18,7 @@ rm -f .bazelrc
 if python -c "import tensorflow as tf" &> /dev/null; then
     echo 'using installed tensorflow'
 else
-    pip install tensorflow
+    pip install --upgrade tensorflow==1.14.0
 fi
 python -m pip install grpcio-tools
 python config_helper.py

dev/Dockerfile

@@ -44,6 +44,7 @@ RUN /bin/bash -c "source activate tfio-dev && python -m pip install \
     pyarrow==${ARROW_VERSION} \
     pandas \
     fastavro \
+    gast==0.2.2 \
     ${PIP_ADD_PACKAGES} \
     "
 

setup.py

@@ -95,7 +95,7 @@ def has_ext_modules(self):
 """
 
 package = 'tensorflow>=1.14.0,<1.15.0'
-version = '0.7.0'
+version = '0.7.1'
 project = 'tensorflow-io'
 if '--package-version' in sys.argv:
   print(package)

tensorflow_io/bigquery/BUILD

@@ -9,6 +9,20 @@ load(
     "tf_io_copts",
 )
 
+py_library(
+    name = "bigquery",
+    srcs = [
+        "__init__.py",
+        "python/__init__.py",
+        "python/ops/__init__.py",
+        "python/ops/bigquery_api.py",
+    ],
+    data = [
+        ":python/ops/_bigquery.so",
+    ],
+    srcs_version = "PY2AND3",
+)
+
 KERNEL_FILES = [
     "kernels/bigquery_kernels.cc",
     "kernels/bigquery_dataset_op.cc",

tensorflow_io/bigquery/README.md

@@ -0,0 +1,89 @@
+# Google BigQuery
+
+[BigQuery](https://cloud.google.com/bigquery/) is a serverless, highly-scalable,
+and cost-effective cloud data warehouse with an in-memory BI Engine and machine
+learning built in.
+
+BigQuery connector relies on [BigQuery Storage API](https://cloud.google.com/bigquery/docs/reference/storage/).
+that provides fast access to BigQuery managed storage by using an rpc-based
+protocol.
+
+## Prerequisites
+
+In order to use BigQuery connector, you need to make sure that Google Cloud SDK
+is propertly configured and that you have BigQuery Storage API enabled.
+Depending on environment you are using some prerequisites might be already met.
+
+1. [Select or create a GCP project.](https://pantheon.corp.google.com/projectselector2/home/dashboard)
+2. [Install and initialize the Cloud SDK.](https://cloud.google.com/sdk/docs/)
+3. [Setup Authentication.](https://cloud.google.com/docs/authentication/#service_accounts)
+If you choose to use [service account](https://cloud.google.com/docs/authentication/production)
+authentication, please make sure that GOOGLE_APPLICATION_CREDENTIALS
+environment variable is initialized with a path pointing to JSON file that
+contains your service account key.
+4. [Enable BigQuery Storage API.](https://cloud.google.com/bigquery/docs/reference/storage/#enabling_the_api)
+
+## Sample Use
+
+BigQuery connector mostly follows [BigQuery Storage API flow](https://cloud.google.com/bigquery/docs/reference/storage/#basic_api_flow),
+but hides complexity associated with decoding serialized data rows into Tensors.
+
+1. Create a `BigQueryClient` client.
+2. Use the `BigQueryClient` to create `BigQueryReadSession` object corresponding
+    to a read session. A read session divides the contents of a BigQuery table
+    into one or more streams, which can then be used to read data from the
+    table.
+3. Call parallel_read_rows on `BigQueryReadSession` object to read from multiple
+    BigQuery streams in parallel.
+
+The following example illustrates how to read particular columns from public
+BigQuery dataset.
+
+```python
+from tensorflow.python.framework import ops
+from tensorflow.python.framework import dtypes
+from tensorflow_io.bigquery import BigQueryClient
+from tensorflow_io.bigquery import BigQueryReadSession
+
+GCP_PROJECT_ID = '<FILL_ME_IN>'
+DATASET_GCP_PROJECT_ID = "bigquery-public-data"
+DATASET_ID = "samples"
+TABLE_ID = "wikipedia"
+
+def main():
+  ops.enable_eager_execution()
+  client = BigQueryClient()
+  read_session = client.read_session(
+      "projects/" + GCP_PROJECT_ID,
+      DATASET_GCP_PROJECT_ID, TABLE_ID, DATASET_ID,
+      ["title",
+       "id",
+       "num_characters",
+       "language",
+       "timestamp",
+       "wp_namespace",
+       "contributor_username"],
+      [dtypes.string,
+       dtypes.int64,
+       dtypes.int64,
+       dtypes.string,
+       dtypes.int64,
+       dtypes.int64,
+       dtypes.string],
+      requested_streams=2,
+      row_restriction="num_characters > 1000")
+  dataset = read_session.parallel_read_rows()
+
+  row_index = 0
+  for row in dataset.prefetch(10):
+    print("row %d: %s" % (row_index, row))
+    row_index += 1
+
+if __name__ == '__main__':
+  app.run(main)
+
+```
+
+Please refer to BigQuery connector Python docstrings and to
+[Enable BigQuery Storage API](https://cloud.google.com/bigquery/docs/reference/storage/rpc/)
+documentation for more details about each parameter.

tensorflow_io/bigquery/kernels/bigquery_kernels.cc

@@ -146,6 +146,8 @@ class BigQueryReadSessionOp : public OpKernel {
     *createReadSessionRequest.mutable_read_options()
          ->mutable_selected_fields() = {selected_fields_.begin(),
                                         selected_fields_.end()};
+    createReadSessionRequest.mutable_read_options()->set_row_restriction(
+        row_restriction_);                                        
     createReadSessionRequest.set_requested_streams(requested_streams_);
     createReadSessionRequest.set_format(apiv1beta1::DataFormat::AVRO);
     VLOG(3) << "createReadSessionRequest: "

tensorflow_io/bigquery/kernels/bigquery_lib.h

@@ -184,6 +184,9 @@ class BigQueryReaderDatasetIterator : public DatasetIterator<Dataset> {
         case avro::AVRO_ENUM:
           dtype = DT_STRING;
           break;
+        case avro::AVRO_NULL:
+          dtype = output_types[i];
+          break;
         default:
           return errors::InvalidArgument("unsupported data type: ",
                                          field.type());
@@ -250,6 +253,8 @@ class BigQueryReaderDatasetIterator : public DatasetIterator<Dataset> {
           ((*out_tensors)[i]).scalar<string>()() =
               field.value<avro::GenericEnum>().symbol();
           break;
+        case avro::AVRO_NULL:  // Fallthrough;
+          break;
         default:
           return errors::InvalidArgument("unsupported data type: ",
                                          field.type());

tensorflow_io/bigquery/python/__init__.py

@@ -0,0 +1,20 @@
+# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""This module contains the Python API for the Cloud BigQuery integration."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function