Rewrite link parsing for finding v2 schemas

What we called 'links' are no longer returned in a container of
objects, they are top-level entity attribtues. This fixes the
parsing of the entities to look in the correct place when trying
to locate a specific schema.

Add a helper for printing to stderr and exiting with a non-zero
exit code.

Map 'name' to 'Attribute' when explaining a schema.

Related to bp glance-client-v2

Change-Id: Ib98e912a7af0bb570b4fd738733edd9b837d1a05

glanceclient/common/utils.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import os
+import sys
 import uuid
 
 import prettytable
@@ -47,7 +48,7 @@ def print_list(objs, fields, formatters={}):
                 row.append(formatters[field](o))
             else:
                 field_name = field.lower().replace(' ', '_')
-                data = getattr(o, field_name, '')
+                data = getattr(o, field_name, None) or ''
                 row.append(data)
         pt.add_row(row)
 
@@ -123,3 +124,9 @@ def import_versioned_module(version, submodule=None):
     if submodule:
         module = '.'.join((module, submodule))
     return importutils.import_module(module)
+
+
+def exit(msg=''):
+    if msg:
+        print >> sys.stderr, msg
+    sys.exit(1)

glanceclient/v2/schemas.py

@@ -52,7 +52,7 @@ class Controller(object):
 
     def _find_schema_uri(self, schema_name):
         _, schema_index = self.http_client.json_request('GET', '/v2/schemas')
-        for link in schema_index['links']:
-            if link['rel'] == schema_name:
-                return link['href']
-        raise exc.SchemaNotFound(schema_name)
+        try:
+            return schema_index[schema_name]
+        except KeyError:
+            raise exc.SchemaNotFound(schema_name)

glanceclient/v2/shell.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 from glanceclient.common import utils
+from glanceclient import exc
 
 
 def do_image_list(gc, args):
@@ -23,9 +24,14 @@ def do_image_list(gc, args):
     utils.print_list(images, columns)
 
 
-@utils.arg('name', metavar='<NAME>', help='Name of model to describe.')
+@utils.arg('model', metavar='<MODEL>', help='Name of model to describe.')
 def do_explain(gc, args):
     """Describe a specific model."""
-    schema = gc.schemas.get(args.name)
-    columns = ['Name', 'Description']
-    utils.print_list(schema.properties, columns)
+    try:
+        schema = gc.schemas.get(args.model)
+    except exc.SchemaNotFound:
+        utils.exit('Unable to find requested model \'%s\'' % args.model)
+    else:
+        formatters = {'Attribute': lambda m: m.name}
+        columns = ['Attribute', 'Description']
+        utils.print_list(schema.properties, columns, formatters)

tests/v2/test_schemas.py

@@ -23,10 +23,10 @@ fixtures = {
     '/v2/schemas': {
         'GET': (
             {},
-            {'links': [
-                {'rel': 'image', 'href': '/v2/schemas/image'},
-                {'rel': 'access', 'href': '/v2/schemas/image/access'},
-            ]},
+            {
+                'image': '/v2/schemas/image',
+                'access': '/v2/schemas/image/access',
+            },
         ),
     },
     '/v2/schemas/image': {