Support schema types with non-str value

Change I75da1e9309e0f7ef8839dea3ec9c99c58edc5d63 introduced some
properties' types which are not string. This broke the `schema_args`
utility since lists are not hashable and there was no support for such
type values.

This patch fixes this issue with a very glance specific strategy in
which this values are assumed to have a `null` type and another type -
string, integer, etc. The fix ignores `null` options and it takes the
first non-null type as the valid one.

The patch adds support for enum types that accept `None`

Closes-bug: #1401032
Change-Id: I250e8912aca262a56c54ac59bb24f917e5d8cfce

glanceclient/common/utils.py

@@ -81,6 +81,17 @@ def schema_args(schema_getter, omit=None):
                 kwargs = {}
 
                 type_str = property.get('type', 'string')
+
+                if isinstance(type_str, list):
+                    # NOTE(flaper87): This means the server has
+                    # returned something like `['null', 'string']`,
+                    # therfore we use the first non-`null` type as
+                    # the valid type.
+                    for t in type_str:
+                        if t != 'null':
+                            type_str = t
+                            break
+
                 if type_str == 'array':
                     items = property.get('items')
                     kwargs['type'] = typemap.get(items.get('type'))
@@ -97,8 +108,13 @@ def schema_args(schema_getter, omit=None):
                 if 'enum' in property:
                     if len(description):
                         description += " "
-                    description += ("Valid values: " +
-                                    ', '.join(property.get('enum')))
+
+                    # NOTE(flaper87): Make sure all values are `str/unicode`
+                    # for the `join` to succeed. Enum types can also be `None`
+                    # therfore, join's call would fail without the following
+                    # list comprehension
+                    vals = [six.text_type(val) for val in property.get('enum')]
+                    description += ('Valid values: ' + ', '.join(vals))
                 kwargs['help'] = description
 
                 func.__dict__.setdefault('arguments',