Add async networking libraries support

pyodata/client.py

@@ -6,13 +6,31 @@
 import pyodata.v2.model
 import pyodata.v2.service
 from pyodata.exceptions import PyODataException, HttpError
+from pyodata.v2.response import Response
+
+
+async def _async_fetch_metadata(connection, url, logger):
+    logger.info('Fetching metadata')
+
+    async with connection.get(url + '$metadata') as async_response:
+        resp = Response()
+        resp.url = async_response.url
+        resp.headers = async_response.headers
+        resp.status_code = async_response.status
+        resp.content = await async_response.read()
+
+        return _common_fetch_metadata(resp, logger)
 
 
 def _fetch_metadata(connection, url, logger):
     # download metadata
     logger.info('Fetching metadata')
     resp = connection.get(url + '$metadata')
 
+    return _common_fetch_metadata(resp, logger)
+
+
+def _common_fetch_metadata(resp, logger):
     logger.debug('Retrieved the response:\n%s\n%s',
                  '\n'.join((f'H: {key}: {value}' for key, value in resp.headers.items())),
                  resp.content)
@@ -37,6 +55,25 @@ class Client:
 
     ODATA_VERSION_2 = 2
 
+    @staticmethod
+    async def build_async_client(url, connection, odata_version=ODATA_VERSION_2, namespaces=None,
+                                 config: pyodata.v2.model.Config = None, metadata: str = None):
+        """Create instance of the OData Client for given URL"""
+
+        logger = logging.getLogger('pyodata.client')
+
+        if odata_version == Client.ODATA_VERSION_2:
+
+            # sanitize url
+            url = url.rstrip('/') + '/'
+
+            if metadata is None:
+                metadata = await _async_fetch_metadata(connection, url, logger)
+            else:
+                logger.info('Using static metadata')
+            return Client._build_service(logger, url, connection, odata_version, namespaces, config, metadata)
+        raise PyODataException(f'No implementation for selected odata version {odata_version}')
+
     def __new__(cls, url, connection, odata_version=ODATA_VERSION_2, namespaces=None,
                 config: pyodata.v2.model.Config = None, metadata: str = None):
         """Create instance of the OData Client for given URL"""
@@ -53,24 +90,29 @@ def __new__(cls, url, connection, odata_version=ODATA_VERSION_2, namespaces=None
             else:
                 logger.info('Using static metadata')
 
-            if config is not None and namespaces is not None:
-                raise PyODataException('You cannot pass namespaces and config at the same time')
+            return Client._build_service(logger, url, connection, odata_version, namespaces, config, metadata)
+        raise PyODataException(f'No implementation for selected odata version {odata_version}')
 
-            if config is None:
-                config = pyodata.v2.model.Config()
+    @staticmethod
+    def _build_service(logger, url, connection, odata_version=ODATA_VERSION_2, namespaces=None,
+                       config: pyodata.v2.model.Config = None, metadata: str = None):
 
-            if namespaces is not None:
-                warnings.warn("Passing namespaces directly is deprecated. Use class Config instead", DeprecationWarning)
-                config.namespaces = namespaces
+        if config is not None and namespaces is not None:
+            raise PyODataException('You cannot pass namespaces and config at the same time')
 
-            # create model instance from received metadata
-            logger.info('Creating OData Schema (version: %d)', odata_version)
-            schema = pyodata.v2.model.MetadataBuilder(metadata, config=config).build()
+        if config is None:
+            config = pyodata.v2.model.Config()
 
-            # create service instance based on model we have
-            logger.info('Creating OData Service (version: %d)', odata_version)
-            service = pyodata.v2.service.Service(url, schema, connection, config=config)
+        if namespaces is not None:
+            warnings.warn("Passing namespaces directly is deprecated. Use class Config instead", DeprecationWarning)
+            config.namespaces = namespaces
 
-            return service
+        # create model instance from received metadata
+        logger.info('Creating OData Schema (version: %d)', odata_version)
+        schema = pyodata.v2.model.MetadataBuilder(metadata, config=config).build()
 
-        raise PyODataException(f'No implementation for selected odata version {odata_version}')
+        # create service instance based on model we have
+        logger.info('Creating OData Service (version: %d)', odata_version)
+        service = pyodata.v2.service.Service(url, schema, connection, config=config)
+
+        return service

pyodata/v2/response.py

@@ -0,0 +1,32 @@
+"""
+Utility class to standardize response
+
+Author: Alberto Moio <email Alberto>, Nunzio Mauro <mnunzio90@gmail.com>
+Date:   2017-08-21
+"""
+import json
+
+
+class Response:
+    """Representation of http response in a standard form already used by handlers"""
+
+    __attrs__ = [
+        'content', 'status_code', 'headers', 'url'
+    ]
+
+    def __init__(self):
+        self.status_code = None
+        self.headers = None
+        self.url = None
+        self.content = None
+
+    @property
+    def text(self):
+        """Textual representation of response content"""
+
+        return self.content.decode('utf-8')
+
+    def json(self):
+        """JSON representation of response content"""
+
+        return json.loads(self.text)

pyodata/v2/service.py

@@ -18,6 +18,7 @@
 
 from pyodata.exceptions import HttpError, PyODataException, ExpressionError, ProgramError
 from . import model
+from .response import Response
 
 LOGGER_NAME = 'pyodata.service'
 
@@ -292,14 +293,7 @@ def add_headers(self, value):
 
         self._headers.update(value)
 
-    def execute(self):
-        """Fetches HTTP response and returns processed result
-
-           Sends the query-request to the OData service, returning a client-side Enumerable for
-           subsequent in-memory operations.
-
-           Fetches HTTP response and returns processed result"""
-
+    def _build_request(self):
         if self._next_url:
             url = self._next_url
         else:
@@ -315,10 +309,47 @@ def execute(self):
         if body:
             self._logger.debug('  body: %s', body)
 
-        params = urlencode(self.get_query_params())
+        params = self.get_query_params()
+
+        return url, body, headers, params
+
+    async def async_execute(self):
+        """Fetches HTTP response and returns processed result
+
+                  Sends the query-request to the OData service, returning a client-side Enumerable for
+                  subsequent in-memory operations.
+
+                  Fetches HTTP response and returns processed result"""
+
+        url, body, headers, params = self._build_request()
+        async with self._connection.request(self.get_method(),
+                                            url,
+                                            headers=headers,
+                                            params=params,
+                                            data=body) as async_response:
+            response = Response()
+            response.url = async_response.url
+            response.headers = async_response.headers
+            response.status_code = async_response.status
+            response.content = await async_response.read()
+        return self._call_handler(response)
+
+    def execute(self):
+        """Fetches HTTP response and returns processed result
+
+           Sends the query-request to the OData service, returning a client-side Enumerable for
+           subsequent in-memory operations.
+
+           Fetches HTTP response and returns processed result"""
+
+        url, body, headers, params = self._build_request()
+
         response = self._connection.request(
-            self.get_method(), url, headers=headers, params=params, data=body)
+            self.get_method(), url, headers=headers, params=urlencode(params), data=body)
 
+        return self._call_handler(response)
+
+    def _call_handler(self, response):
         self._logger.debug('Received response')
         self._logger.debug('  url: %s', response.url)
         self._logger.debug('  headers: %s', response.headers)
@@ -858,6 +889,19 @@ def __getattr__(self, attr):
                 raise AttributeError('EntityType {0} does not have Property {1}: {2}'
                                      .format(self._entity_type.name, attr, str(ex)))
 
+    async def getattr(self, attr):
+        """Get cached value of attribute or do async call to service to recover attribute value"""
+        try:
+            return self._cache[attr]
+        except KeyError:
+            try:
+                value = await self.get_proprty(attr).async_execute()
+                self._cache[attr] = value
+                return value
+            except KeyError as ex:
+                raise AttributeError('EntityType {0} does not have Property {1}: {2}'
+                                     .format(self._entity_type.name, attr, str(ex)))
+
     def nav(self, nav_property):
         """Navigates to given navigation property and returns the EntitySetProxy"""
 
@@ -1686,6 +1730,16 @@ def http_get(self, path, connection=None):
 
         return conn.get(urljoin(self._url, path))
 
+    async def async_http_get(self, path, connection=None):
+        """HTTP GET response for the passed path in the service"""
+
+        conn = connection
+        if conn is None:
+            conn = self._connection
+
+        async with conn.get(urljoin(self._url, path)) as resp:
+            return resp
+
     def http_get_odata(self, path, handler, connection=None):
         """HTTP GET request proxy for the passed path in the service"""