Define utils.py

- Utility functions to assist with connecting to a LabKey instance.
- create_server_context, build_url, and handle_response

Author: labkey-nicka

labkey/utils.py

@@ -0,0 +1,115 @@
+#
+# Copyright (c) 2015 LabKey Corporation
+#
+# 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.
+#
+from __future__ import unicode_literals
+
+import requests
+import ssl
+
+from requests.adapters import HTTPAdapter
+from requests.packages.urllib3.poolmanager import PoolManager
+
+
+# _ssl.c:504: error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure
+# http://lukasa.co.uk/2013/01/Choosing_SSL_Version_In_Requests/
+class SafeTLSAdapter(HTTPAdapter):
+    def init_poolmanager(self, connections, maxsize, block=False):
+        self.poolmanager = PoolManager(num_pools=connections,
+                                       maxsize=maxsize,
+                                       block=block,
+                                       ssl_version=ssl.PROTOCOL_TLSv1)
+
+
+def create_server_context(domain, container_path, context_path=None, use_ssl=True):
+    # TODO: Document
+    server_context = dict(domain=domain, container_path=container_path, context_path=context_path)
+
+    if use_ssl:
+        scheme = 'https'
+    else:
+        scheme = 'http'
+    scheme += '://'
+
+    if use_ssl:
+        session = requests.Session()
+        session.mount(scheme, SafeTLSAdapter())
+    else:
+        # TODO: Is there a better way? Can we have session.mount('http')?
+        session = requests
+
+    server_context['scheme'] = scheme
+    server_context['session'] = session
+
+    return server_context
+
+
+def build_url(controller, action, server_context, container_path=None):
+    """
+    Builds a URL from a controller and an action. Users the server context to determine domain,
+    context path, container, etc.
+    :param controller: The controller to use in building the URL
+    :param action: The action to use in building the URL
+    :param server_context:
+    :param container_path:
+    :return:
+    """
+    sep = '/'
+
+    url = server_context['scheme']
+    url += server_context['domain']
+
+    if server_context['context_path'] is not None:
+        url += sep + server_context['context_path']
+
+    url += sep + controller
+
+    if container_path is not None:
+        url += sep + container_path
+    else:
+        url += sep + server_context['container_path']
+
+    url += sep + action
+
+    return url
+
+
+def handle_response(response):
+    sc = response.status_code
+
+    if sc == 200 or sc == 207:
+        return response.json()
+    elif sc == 401:
+        print(str(sc) + ": Authorization failed.")
+    elif sc == 404:
+        msg = str(sc) + ": "
+        decoded = response.json()
+        if 'exception' in decoded:
+            msg += decoded['exception']
+        else:
+            msg += 'Not found.'
+        print(msg)
+    elif sc == 500:
+        msg = str(sc) + ": "
+        decoded = response.json()
+        if 'exception' in decoded:
+            msg += decoded['exception']
+        else:
+            msg += 'Internal Server Error.'
+        print(msg)
+    else:
+        print(str(sc))
+        print(response.json())
+
+    return None