Add find method to resource

Add a find method to the resource to search by name or id.

Change-Id: I993e0ab2fffd3cd10407406316c483f8051dca1b

openstack/exceptions.py

@@ -66,3 +66,13 @@ class HttpException(SDKException):
 class MethodNotSupported(SDKException):
     """The resource does not support this operation type."""
     pass
+
+
+class ResourceNotFound(SDKException):
+    """The requested resource was not found."""
+    pass
+
+
+class DuplicateResource(SDKException):
+    """More than one resource exists with that name."""
+    pass

openstack/resource.py

@@ -101,6 +101,9 @@ class Resource(collections.MutableMapping):
     resource_key = None
     resources_key = None
 
+    # The attribute associated with the name
+    name_attribute = 'name'
+
     # the base part of the url for this resource
     base_path = ''
 
@@ -350,3 +353,24 @@ class Resource(collections.MutableMapping):
             resp = resp[cls.resources_key]
 
         return [cls.existing(**data) for data in resp]
+
+    @classmethod
+    def find(cls, session, name_or_id):
+        try:
+            info = cls.list(session, id=name_or_id, fields='id')
+            if len(info) == 1:
+                return info[0]
+        except exceptions.HttpException:
+            pass
+        if cls.name_attribute:
+            params = {cls.name_attribute: name_or_id, 'fields': 'id'}
+            info = cls.list(session, **params)
+            if len(info) == 1:
+                return info[0]
+            if len(info) > 1:
+                msg = "More than one %s exists with the name '%s'."
+                msg = (msg % (cls.resource_key, name_or_id))
+                raise exceptions.DuplicateResource(msg)
+        msg = ("No %s with a name or ID of '%s' exists." %
+               (cls.resource_key, name_or_id))
+        raise exceptions.ResourceNotFound(msg)

openstack/tests/test_resource.py

@@ -11,7 +11,9 @@
 # under the License.
 
 import httpretty
+import mock
 
+from openstack import exceptions
 from openstack import resource
 from openstack import session
 from openstack.tests import base
@@ -206,3 +208,81 @@ class ResourceTests(base.TestTransportBase):
             pass
         else:
             self.fail("Didn't raise attribute error")
+
+
+class FakeResponse:
+    def __init__(self, response):
+        self.body = response
+
+
+class TestFind(base.TestCase):
+    NAME = 'matrix'
+    ID = 'Fishburne'
+
+    def setUp(self):
+        super(TestFind, self).setUp()
+        self.mock_session = mock.Mock()
+        self.mock_get = mock.Mock()
+        self.mock_session.get = self.mock_get
+        self.matrix = {'id': self.ID}
+
+    def test_name(self):
+        self.mock_get.side_effect = [
+            FakeResponse({FakeResource.resources_key: []}),
+            FakeResponse({FakeResource.resources_key: [self.matrix]})
+        ]
+
+        result = FakeResource.find(self.mock_session, self.NAME)
+
+        self.assertEqual(self.ID, result.id)
+        p = {'fields': 'id', 'name': self.NAME}
+        self.mock_get.assert_called_with('/fakes', params=p, service=None)
+
+    def test_id(self):
+        resp = FakeResponse({FakeResource.resources_key: [self.matrix]})
+        self.mock_get.return_value = resp
+
+        result = FakeResource.find(self.mock_session, self.ID)
+
+        self.assertEqual(self.ID, result.id)
+        p = {'fields': 'id', 'id': self.ID}
+        self.mock_get.assert_called_with('/fakes', params=p, service=None)
+
+    def test_nameo(self):
+        self.mock_get.side_effect = [
+            FakeResponse({FakeResource.resources_key: []}),
+            FakeResponse({FakeResource.resources_key: [self.matrix]})
+        ]
+        FakeResource.name_attribute = 'nameo'
+
+        result = FakeResource.find(self.mock_session, self.NAME)
+
+        FakeResource.name_attribute = 'name'
+        self.assertEqual(self.ID, result.id)
+        p = {'fields': 'id', 'nameo': self.NAME}
+        self.mock_get.assert_called_with('/fakes', params=p, service=None)
+
+    def test_dups(self):
+        dup = {'id': 'Larry'}
+        resp = FakeResponse({FakeResource.resources_key: [self.matrix, dup]})
+        self.mock_get.return_value = resp
+
+        self.assertRaises(exceptions.DuplicateResource, FakeResource.find,
+                          self.mock_session, self.NAME)
+
+    def test_nada(self):
+        resp = FakeResponse({FakeResource.resources_key: []})
+        self.mock_get.return_value = resp
+
+        self.assertRaises(exceptions.ResourceNotFound, FakeResource.find,
+                          self.mock_session, self.NAME)
+
+    def test_no_name(self):
+        self.mock_get.side_effect = [
+            FakeResponse({FakeResource.resources_key: []}),
+            FakeResponse({FakeResource.resources_key: [self.matrix]})
+        ]
+        FakeResource.name_attribute = None
+
+        self.assertRaises(exceptions.ResourceNotFound, FakeResource.find,
+                          self.mock_session, self.NAME)