Manager for generic CRUD on v3

Change-Id: I15944f2e171e26b5209b55356edd1110b301310c

keystoneclient/base.py

@@ -18,6 +18,8 @@
 Base utilities to build API operation managers and objects on top of.
 """
 
+import urllib
+
 from keystoneclient import exceptions
 
 
@@ -144,6 +146,115 @@ class ManagerWithFind(Manager):
         return found
 
 
+class CrudManager(Manager):
+    """Base manager class for manipulating Keystone entities.
+
+    Children of this class are expected to define a `collection_key` and `key`.
+
+    - `collection_key`: Usually a plural noun by convention (e.g. `entities`);
+      used to refer collections in both URL's (e.g.  `/v3/entities`) and JSON
+      objects containing a list of member resources (e.g. `{'entities': [{},
+      {}, {}]}`).
+    - `key`: Usually a singular noun by convention (e.g. `entity`); used to
+      refer to an individual member of the collection.
+
+    """
+    collection_key = None
+    key = None
+
+    def build_url(self, base_url=None, **kwargs):
+        """Builds a resource URL for the given kwargs.
+
+        Given an example collection where `collection_key = 'entities'` and
+        `key = 'entity'`, the following URL's could be generated.
+
+        By default, the URL will represent a collection of entities, e.g.::
+
+            /entities
+
+        If kwargs contains an `entity_id`, then the URL will represent a
+        specific member, e.g.::
+
+            /entities/{entity_id}
+
+        If a `base_url` is provided, the generated URL will be appended to it.
+
+        """
+        url = base_url if base_url is not None else ''
+
+        url += '/%s' % self.collection_key
+
+        # do we have a specific entity?
+        entity_id = kwargs.get('%s_id' % self.key)
+        if entity_id is not None:
+            url += '/%s' % entity_id
+
+        return url
+
+    def _filter_kwargs(self, kwargs):
+        # drop null values
+        for key, ref in kwargs.copy().iteritems():
+            if ref is None:
+                kwargs.pop(key)
+            else:
+                id_value = getid(ref)
+                if id_value != ref:
+                    kwargs.pop(key)
+                    kwargs['%s_id' % key] = id_value
+        return kwargs
+
+    def create(self, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+        return self._create(
+            self.build_url(**kwargs),
+            {self.key: kwargs},
+            self.key)
+
+    def get(self, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+        return self._get(
+            self.build_url(**kwargs),
+            self.key)
+
+    def head(self, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+        return self._head(self.build_url(**kwargs))
+
+    def list(self, base_url=None, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+
+        return self._list(
+            '%(base_url)s%(query)s' % {
+                'base_url': self.build_url(base_url=base_url, **kwargs),
+                'query': '?%s' % urllib.urlencode(kwargs) if kwargs else '',
+            },
+            self.collection_key)
+
+    def put(self, base_url=None, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+
+        return self._update(
+            self.build_url(base_url=base_url, **kwargs),
+            method='PUT')
+
+    def update(self, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+        params = kwargs.copy()
+        params.pop('%s_id' % self.key)
+
+        return self._update(
+            self.build_url(**kwargs),
+            {self.key: params},
+            self.key,
+            method='PATCH')
+
+    def delete(self, **kwargs):
+        kwargs = self._filter_kwargs(kwargs)
+
+        return self._delete(
+            self.build_url(**kwargs))
+
+
 class Resource(object):
     """
     A resource represents a particular instance of an object (tenant, user,