# HG changeset patch
# User Todd Larsen <tlarsen@google.com>
# Date 1219958139 0
# Node ID 4d9895fb15bcc0d8ce0de2ab316fa9bb9b519a6b
# Parent  f506a22f50dbaa082288959a1547abb5688ecdb8
Consolidate functions dealing with Google Accounts and look-up of User entities
into a single site-wide controller module.  Tests will be added in a subsequent
commit as soon as Google App Engine tests using mocker are figured out.

Patch by: Todd Larsen
Review by: to-be-reviewed

diff -r f506a22f50db -r 4d9895fb15bc app/soc/logic/site/__init__.py
diff -r f506a22f50db -r 4d9895fb15bc app/soc/logic/site/id_user.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/logic/site/id_user.py	Thu Aug 28 21:15:39 2008 +0000
@@ -0,0 +1,138 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2008 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Basic ID (Google Account) and User (Model) query functions.
+"""
+
+__authors__ = [
+  '"Todd Larsen" <tlarsen@google.com>',
+  ]
+
+
+from google.appengine.api import users
+
+from soc.logic import out_of_band
+
+import soc.models.user
+
+
+def getIdIfMissing(id):
+  """Gets Google Account of logged-in user (possibly None) if id is false.
+  
+  This is a convenience function that simplifies a lot of view code that
+  accepts an optional id argument from the caller (such as one looked up
+  already by another view that decides to "forward" the request to this
+  other view).
+
+  Args:
+    id: a Google Account object, or None
+    
+  Returns:
+    If id is non-false, it is simply returned; otherwise, the Google Account
+    of currently logged-in user is returned (which could be None if no user
+    is logged in).
+  """
+  if not id:
+    # id not initialized, so check if a Google Account is currently logged in
+    id = users.get_current_user()
+
+  return id
+
+  
+def getUserFromId(id):
+  """Returns User entity for a Google Account, or None if not found.  
+    
+  Args:
+    id: a Google Account object
+  """
+  return soc.models.user.User.gql('WHERE id = :1', id).get()
+
+
+def getUserIfMissing(user, id):
+  """Conditionally returns User entity for a Google Account.
+  
+  This function is used to look up the User entity corresponding to the
+  supplied Google Account *if* the user parameter is false (usually None).
+  This function is basically a no-op if user already refers to a User
+  entity.  This is a convenience function that simplifies a lot of view
+  code that accepts an optional user argument from the caller (such as
+  one looked up already by another view that decides to "forward" the
+  HTTP request to this other view).
+
+  Args:
+    user: None (usually), or an existing User entity
+    id: a Google Account object
+    
+  Returns:
+    * user (which may have already been None if passed in that way by the
+      caller) if id is false or user is non-false
+    * results of getUserFromId() if user is false and id is non-false
+  """
+  if id and (not user):
+    # Google Account supplied and User uninitialized, so look up User entity
+    user = getUserFromId(id)
+    
+  return user
+
+
+def doesUserExist(id):
+  """Returns True if User exists in the Datastore for a Google Account.
+    
+  Args:
+    id: a Google Account object
+  """
+  if getUserFromId(id):
+    return True
+  else:
+    return False
+
+
+def getUserFromLinkName(link_name):
+  """Returns User entity for link_name or None if not found.
+    
+  Args:
+    link_name: link name used in URLs to identify user
+  """
+  return soc.models.user.User.gql('WHERE link_name = :1', link_name).get()
+
+
+def getUserIfLinkName(link_name):
+  """Returns User entity for supplied link_name if one exists.
+  
+  Args:
+    link_name: link name used in URLs to identify user
+
+  Returns:
+    * None if link_name is false.
+    * User entity that has supplied link_name
+
+  Raises:
+    out_of_band.ErrorResponse if link_name is not false, but no User entity
+    with the supplied link_name exists in the Datastore
+  """
+  if not link_name:
+    # exit without error, to let view know that link_name was not supplied
+    return None
+
+  link_name_user = getUserFromLinkName(link_name)
+    
+  if link_name_user:
+    # a User has this link name, so return that corresponding User entity
+    return link_name_user
+
+  # else: a link name was supplied, but there is no User that has it
+  raise out_of_band.ErrorResponse(
+      'There is no user with a "link name" of "%s".' % link_name, status=404)