Fix by_email_address (now for users/groups), add by_id for groups.

fas/fas/model.py

@@ -115,7 +115,7 @@ class People(SABase):
         A class method that can be used to search users
         based on their email addresses since it is unique.
         '''
-        return cls.query.join('emails').filter_by(email=email).first()
+        return cls.query.join(['email_purposes', 'person_email']).filter_by(email=email).one()
 
     by_email_address = classmethod(by_email_address)
 
@@ -300,6 +300,24 @@ class Configs(SABase):
 
 class Groups(SABase):
     '''Group that people can belong to.'''
+
+    def by_id(cls, id):
+        '''
+        A class method that can be used to search groups
+        based on their unique id
+        '''
+        return cls.query.filter_by(id=id).one()
+    by_id = classmethod(by_id)
+
+    def by_email_address(cls, email):
+        '''
+        A class method that can be used to search groups
+        based on their email addresses since it is unique.
+        '''
+        return cls.query.join(['group_email_purposes', 'group_email']).filter_by(email=email).one()
+
+    by_email_address = classmethod(by_email_address)
+
     def by_name(cls, name):
         '''
         A class method that permits to search groups