tseaver · Oct 30, 2018 · Oct 19, 2018 · Oct 21, 2018 · Oct 26, 2018 · Oct 26, 2018
diff --git a/bigquery/google/cloud/bigquery/magics.py b/bigquery/google/cloud/bigquery/magics.py
@@ -21,7 +21,7 @@
     .. code-block:: python
 
         %%bigquery [<destination_var>] [--project <project>] [--use_legacy_sql]
-                   [--verbose]
+                   [--verbose] [--params <params>]
         <query>
 
     Parameters:
@@ -39,6 +39,20 @@
         amount of time for the query to complete will not be cleared after the
         query is finished. By default, this information will be displayed but
         will be cleared after the query is finished.
+    * ``--params <params>`` (optional, line argument):
+        If present, the argument following the ``--params`` flag must be
+        either:
+
+        * :class:`str` - A JSON string representation of a dictionary in the
+          format ``{"param_name": "param_value"}`` (ex. ``{"num": 17}``). Use
+          of the parameter in the query should be indicated with
+          ``@param_name``. See ``In[5]`` in the Examples section below.
+
+        * :class:`dict` reference - A reference to a ``dict`` in the format
+          ``{"param_name": "param_value"}``, where the value types must be JSON
+          serializable. The variable reference is indicated by a ``$`` before
+          the variable name (ex. ``$my_dict_var``). See ``In[6]`` and ``In[7]``
+          in the Examples section below.
     * ``<query>`` (required, cell argument):
         SQL query to run.
 
@@ -54,7 +68,7 @@
         the bigquery IPython extension (see ``In[1]``) and setting up
         Application Default Credentials.
 
-    .. code-block:: python
+    .. code-block:: none
 
         In [1]: %load_ext google.cloud.bigquery
 
@@ -96,10 +110,26 @@
            ...: 1    Patricia  1568495
            ...: 2   Elizabeth  1519946
 
+        In [5]: %%bigquery df --params {"num": 17}
+           ...: SELECT @num AS num
+
+        Out[5]:     num
+           ...: -------
+           ...: 0    17
+
+        In [6]: params = {"num": 17}
+
+        In [7]: %%bigquery df --params $params
+           ...: SELECT @num AS num
+
+        Out[7]:     num
+           ...: -------
+           ...: 0    17
 """
 
 from __future__ import print_function
 
+import ast
 import time
 from concurrent import futures
 
@@ -112,6 +142,7 @@
 
 import google.auth
 from google.cloud import bigquery
+from google.cloud.bigquery.dbapi import _helpers
 
 
 class Context(object):
@@ -249,6 +280,16 @@ def _run_query(client, query, job_config=None):
           'amount of time for the query to finish. By default, this '
           'information will be displayed as the query runs, but will be '
           'cleared after the query is finished.'))
+@magic_arguments.argument(
+    '--params',
+    nargs='+',
+    default=None,
+    help=('Parameters to format the query string. If present, the --params '
+          'flag should be followed by a string representation of a dictionary '
+          'in the format {\'param_name\': \'param_value\'} (ex. {"num": 17}), '
+          'or a reference to a dictionary in the same format. The dictionary '
+          'reference can be made by including a \'$\' before the variable '
+          'name (ex. $my_dict_var).'))
 def _cell_magic(line, query):
     """Underlying function for bigquery cell magic
 
@@ -265,9 +306,20 @@ def _cell_magic(line, query):
     """
     args = magic_arguments.parse_argstring(_cell_magic, line)
 
+    params = []
+    if args.params is not None:
+        try:
+            params = _helpers.to_query_parameters(
+                ast.literal_eval(''.join(args.params)))
+        except Exception:
+            raise SyntaxError(
+                '--params is not a correctly formatted JSON string or a JSON '
+                'serializable dictionary')
+
     project = args.project or context.project
     client = bigquery.Client(project=project, credentials=context.credentials)
     job_config = bigquery.job.QueryJobConfig()
+    job_config.query_parameters = params
     job_config.use_legacy_sql = args.use_legacy_sql
     query_job = _run_query(client, query, job_config)
 

diff --git a/bigquery/tests/unit/test_magics.py b/bigquery/tests/unit/test_magics.py
@@ -186,7 +186,7 @@ def test_bigquery_magic_with_result_saved_to_variable():
 
     sql = 'SELECT 17 AS num'
     result = pandas.DataFrame([17], columns=['num'])
-    assert 'myvariable' not in ip.user_ns
+    assert 'df' not in ip.user_ns
 
     run_query_patch = mock.patch(
         'google.cloud.bigquery.magics._run_query', autospec=True)
@@ -259,3 +259,82 @@ def test_bigquery_magic_with_project():
         assert client_used.project == 'specific-project'
         # context project should not change
         assert magics.context.project == 'general-project'
+
+
+@pytest.mark.usefixtures('ipython_interactive')
+@pytest.mark.skipif(pandas is None, reason='Requires `pandas`')
+def test_bigquery_magic_with_string_params():
+    ip = IPython.get_ipython()
+    ip.extension_manager.load_extension('google.cloud.bigquery')
+    magics.context.credentials = mock.create_autospec(
+        google.auth.credentials.Credentials, instance=True)
+
+    sql = 'SELECT @num AS num'
+    result = pandas.DataFrame([17], columns=['num'])
+    assert 'params_string_df' not in ip.user_ns
+
+    run_query_patch = mock.patch(
+        'google.cloud.bigquery.magics._run_query', autospec=True)
+    query_job_mock = mock.create_autospec(
+        google.cloud.bigquery.job.QueryJob, instance=True)
+    query_job_mock.to_dataframe.return_value = result
+    with run_query_patch as run_query_mock:
+        run_query_mock.return_value = query_job_mock
+
+        ip.run_cell_magic(
+            'bigquery', 'params_string_df --params {"num":17}', sql)
+        run_query_mock.assert_called_once_with(
+            mock.ANY, sql.format(num=17), mock.ANY)
+
+    assert 'params_string_df' in ip.user_ns  # verify that the variable exists
+    df = ip.user_ns['params_string_df']
+    assert len(df) == len(result)            # verify row count
+    assert list(df) == list(result)          # verify column names
+
+
+@pytest.mark.usefixtures('ipython_interactive')
+@pytest.mark.skipif(pandas is None, reason='Requires `pandas`')
+def test_bigquery_magic_with_dict_params():
+    ip = IPython.get_ipython()
+    ip.extension_manager.load_extension('google.cloud.bigquery')
+    magics.context.credentials = mock.create_autospec(
+        google.auth.credentials.Credentials, instance=True)
+
+    sql = 'SELECT @num AS num'
+    result = pandas.DataFrame([17], columns=['num'])
+    assert 'params_dict_df' not in ip.user_ns
+
+    run_query_patch = mock.patch(
+        'google.cloud.bigquery.magics._run_query', autospec=True)
+    query_job_mock = mock.create_autospec(
+        google.cloud.bigquery.job.QueryJob, instance=True)
+    query_job_mock.to_dataframe.return_value = result
+    with run_query_patch as run_query_mock:
+        run_query_mock.return_value = query_job_mock
+
+        params = {"num": 17}
+        # Insert dictionary into user namespace so that it can be expanded
+        ip.user_ns['params'] = params
+        ip.run_cell_magic('bigquery', 'params_dict_df --params $params', sql)
+        run_query_mock.assert_called_once_with(
+            mock.ANY, sql.format(num=17), mock.ANY)
+
+    assert 'params_dict_df' in ip.user_ns  # verify that the variable exists
+    df = ip.user_ns['params_dict_df']
+    assert len(df) == len(result)          # verify row count
+    assert list(df) == list(result)        # verify column names
+
+
+@pytest.mark.usefixtures('ipython_interactive')
+@pytest.mark.skipif(pandas is None, reason='Requires `pandas`')
+def test_bigquery_magic_with_improperly_formatted_params():
+    ip = IPython.get_ipython()
+    ip.extension_manager.load_extension('google.cloud.bigquery')
+    magics.context.credentials = mock.create_autospec(
+        google.auth.credentials.Credentials, instance=True)
+
+    sql = 'SELECT @num AS num'
+
+    with pytest.raises(SyntaxError):
+        ip.run_cell_magic(
+            'bigquery', '--params {17}', sql)