Factor tip migration out into a mixin

This works around a bug in Sphinx where the print function under Python
2.7 prevents class attributes from showing up in documentation. I want
to be able to document some attributes on the Team class.

gratipay/models/team/__init__.py

@@ -12,6 +12,7 @@
 from postgres.orm import Model
 
 from gratipay.billing.exchanges import MINIMUM_CHARGE
+from gratipay.models.team.mixins import TipMigration
 
 # Should have at least one letter.
 TEAM_NAME_PATTERN = re.compile(r'^(?=.*[A-Za-z])([A-Za-z0-9.,-_ ]+)$')
@@ -32,7 +33,7 @@ def slugize(name):
     return slug
 
 
-class Team(Model):
+class Team(Model, TipMigration):
     """Represent a Gratipay team.
     """
 
@@ -303,50 +304,6 @@ def to_dict(self):
             'todo_url': self.todo_url
         }
 
-    def migrate_tips(self):
-        """Migrate the Team owner's Gratipay 1.0 tips into 2.0 payment instructions to the Team.
-
-        :return: ``None``
-        :raises: :py:exc:`~gratipay.models.team.AlreadyMigrated` if payment
-            instructions already exist for this Team
-
-        This method gets called under :py:func:`migrate_all_tips` during payday.
-
-        """
-        payment_instructions = self.db.all("""
-            SELECT pi.*
-              FROM payment_instructions pi
-              JOIN teams t ON t.id = pi.team_id
-             WHERE t.owner = %s
-               AND pi.ctime < t.ctime
-        """, (self.owner, ))
-
-        # Make sure the migration hasn't been done already
-        if payment_instructions:
-            raise AlreadyMigrated
-
-        return self.db.one("""
-        WITH rows AS (
-
-            INSERT INTO payment_instructions
-                        (ctime, mtime, participant_id, team_id, amount, is_funded)
-                 SELECT ct.ctime
-                      , ct.mtime
-                      , (SELECT id FROM participants WHERE username=ct.tipper)
-                      , %(team_id)s
-                      , ct.amount
-                      , ct.is_funded
-                   FROM current_tips ct
-                   JOIN participants p ON p.username = tipper
-                  WHERE ct.tippee=%(owner)s
-                    AND p.claimed_time IS NOT NULL
-                    AND p.is_suspicious IS NOT TRUE
-                    AND p.is_closed IS NOT TRUE
-              RETURNING 1
-
-        ) SELECT count(*) FROM rows;
-        """, {'team_id': self.id, 'owner': self.owner})
-
 
     # Images
     # ======
@@ -389,50 +346,3 @@ def load_image(self, size):
             with self.db.get_connection() as c:
                 image = c.lobject(oid, mode='rb').read()
         return image
-
-
-def migrate_all_tips(db, print=print):
-    """Migrate tips for all teams.
-
-    :param GratipayDB db: a database object
-    :param func print: a function that takes lines of log output
-    :returns: ``None``
-
-    This function loads :py:class:`~gratipay.models.team.Team` objects for all
-    Teams where the owner had tips under Gratipay 1.0 but those tips have not
-    yet been migrated into payment instructions under Gratipay 2.0. It then
-    migrates the tips using :py:meth:`~gratipay.models.team.Team.migrate_tips`.
-
-    This function is wrapped in a script, ``bin/migrate-tips.py``, which is
-    `used during payday`_.
-
-    .. _used during payday: http://inside.gratipay.com/howto/run-payday
-
-    """
-    teams = db.all("""
-        SELECT distinct ON (t.id) t.*::teams
-          FROM teams t
-          JOIN tips ON t.owner = tips.tippee    -- Only fetch teams whose owners had tips under Gratipay 1.0
-         WHERE t.is_approved IS TRUE            -- Only fetch approved teams
-           AND NOT EXISTS (                     -- Make sure tips haven't been migrated for any teams with same owner
-                SELECT 1
-                  FROM payment_instructions pi
-                  JOIN teams t2 ON t2.id = pi.team_id
-                 WHERE t2.owner = t.owner
-                   AND pi.ctime < t2.ctime
-           )
-    """)
-
-    for team in teams:
-        try:
-            ntips = team.migrate_tips()
-            print("Migrated {} tip(s) for '{}'".format(ntips, team.slug))
-        except AlreadyMigrated:
-            print("'%s' already migrated." % team.slug)
-
-    print("Done.")
-
-
-class AlreadyMigrated(Exception):
-    """Raised by :py:meth:`~gratipay.models.team.migrate_tips`.
-    """

gratipay/models/team/mixins/__init__.py

@@ -0,0 +1,3 @@
+from .tip_migration import TipMigrationMixin as TipMigration
+
+__all__ = ['TipMigration']

gratipay/models/team/mixins/tip_migration.py

@@ -0,0 +1,101 @@
+"""Participants who received tips directly under Gittipay 1.0 will have their
+tips migrated if and when they become the owner of a new Gratipay 2.0 team.
+"""
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+
+class TipMigrationMixin(object):
+    """This mixin provides tip migration for teams.
+    """
+
+    def migrate_tips(self):
+        """Migrate the Team owner's Gratipay 1.0 tips into 2.0 payment instructions to the Team.
+
+        :return: ``None``
+        :raises: :py:exc:`~gratipay.models.team.AlreadyMigrated` if payment
+            instructions already exist for this Team
+
+        This method gets called under :py:func:`migrate_all_tips` during payday.
+
+        """
+        payment_instructions = self.db.all("""
+            SELECT pi.*
+              FROM payment_instructions pi
+              JOIN teams t ON t.id = pi.team_id
+             WHERE t.owner = %s
+               AND pi.ctime < t.ctime
+        """, (self.owner, ))
+
+        # Make sure the migration hasn't been done already
+        if payment_instructions:
+            raise AlreadyMigrated
+
+        return self.db.one("""
+        WITH rows AS (
+
+            INSERT INTO payment_instructions
+                        (ctime, mtime, participant_id, team_id, amount, is_funded)
+                 SELECT ct.ctime
+                      , ct.mtime
+                      , (SELECT id FROM participants WHERE username=ct.tipper)
+                      , %(team_id)s
+                      , ct.amount
+                      , ct.is_funded
+                   FROM current_tips ct
+                   JOIN participants p ON p.username = tipper
+                  WHERE ct.tippee=%(owner)s
+                    AND p.claimed_time IS NOT NULL
+                    AND p.is_suspicious IS NOT TRUE
+                    AND p.is_closed IS NOT TRUE
+              RETURNING 1
+
+        ) SELECT count(*) FROM rows;
+        """, {'team_id': self.id, 'owner': self.owner})
+
+
+def migrate_all_tips(db, print=print):
+    """Migrate tips for all teams.
+
+    :param GratipayDB db: a database object
+    :param func print: a function that takes lines of log output
+    :returns: ``None``
+
+    This function loads :py:class:`~gratipay.models.team.Team` objects for all
+    Teams where the owner had tips under Gratipay 1.0 but those tips have not
+    yet been migrated into payment instructions under Gratipay 2.0. It then
+    migrates the tips using :py:meth:`~gratipay.models.team.Team.migrate_tips`.
+
+    This function is wrapped in a script, ``bin/migrate-tips.py``, which is
+    `used during payday`_.
+
+    .. _used during payday: http://inside.gratipay.com/howto/run-payday
+
+    """
+    teams = db.all("""
+        SELECT distinct ON (t.id) t.*::teams
+          FROM teams t
+          JOIN tips ON t.owner = tips.tippee    -- Only fetch teams whose owners had tips under Gratipay 1.0
+         WHERE t.is_approved IS TRUE            -- Only fetch approved teams
+           AND NOT EXISTS (                     -- Make sure tips haven't been migrated for any teams with same owner
+                SELECT 1
+                  FROM payment_instructions pi
+                  JOIN teams t2 ON t2.id = pi.team_id
+                 WHERE t2.owner = t.owner
+                   AND pi.ctime < t2.ctime
+           )
+    """)
+
+    for team in teams:
+        try:
+            ntips = team.migrate_tips()
+            print("Migrated {} tip(s) for '{}'".format(ntips, team.slug))
+        except AlreadyMigrated:
+            print("'%s' already migrated." % team.slug)
+
+    print("Done.")
+
+
+class AlreadyMigrated(Exception):
+    """Raised by :py:meth:`~gratipay.models.team.migrate_tips`.
+    """

tests/py/test_tip_migration.py

@@ -2,7 +2,7 @@
 
 import pytest
 from gratipay.testing import Harness
-from gratipay.models.team import AlreadyMigrated, migrate_all_tips
+from gratipay.models.team.mixins.tip_migration import AlreadyMigrated, migrate_all_tips
 
 
 class Tests(Harness):