Don't change user names to ids in user_id_or_name_exists

The user_id_or_name_exists() validator was returning the user id if the
given argument was a user name. Return the user name instead. If the
given argument is a user id, still return the user id as before.

Also added a convert_user_id_or_name_to_id() converter for when you
don't want the id returned if a name is given.

ckan/logic/converters.py

@@ -82,3 +82,27 @@ def callable(key, data, errors, context):
         data[key] = tags
     return callable
 
+def convert_user_name_or_id_to_id(user_name_or_id, context):
+    '''Return the user id for the given user name or id.
+
+    The point of this function is to convert user names to ids. If you have
+    something that may be a user name or a user id you can pass it into this
+    function and get the user id out either way.
+
+    Also validates that a user with the given name or id exists.
+
+    :returns: the id of the user with the given user name or id
+    :rtype: string
+    :raises: ckan.lib.navl.dictization_functions.Invalid if no user can be
+        found with the given id or user name
+
+    '''
+    session = context['session']
+    result = session.query(model.User).filter_by(id=user_name_or_id).first()
+    if not result:
+        result = session.query(model.User).filter_by(
+                name=user_name_or_id).first()
+    if not result:
+        raise Invalid('%s: %s' % (_('Not found'), _('User')))
+    else:
+        return result.id

ckan/logic/validators.py

@@ -102,6 +102,12 @@ def user_id_exists(user_id, context):
     return user_id
 
 def user_id_or_name_exists(user_id_or_name, context):
+    '''Return the given user_id_or_name if such a user exists.
+
+    :raises: ckan.lib.navl.dictization_functions.Invalid if no user can be
+        found with the given id or user name
+
+    '''
     model = context['model']
     session = context['session']
     result = session.query(model.User).get(user_id_or_name)
@@ -110,7 +116,7 @@ def user_id_or_name_exists(user_id_or_name, context):
     result = session.query(model.User).filter_by(name=user_id_or_name).first()
     if not result:
         raise Invalid('%s: %s' % (_('Not found'), _('User')))
-    return result.id
+    return user_id_or_name
 
 def group_id_exists(group_id, context):
     """Raises Invalid if the given group_id does not exist in the model given