Fixed #23822 -- Added support for serializing model managers in migration

Thanks to Shai Berger, Loïc Bistuer, Simon Charette, Andrew Godwin,
Tim Graham, Carl Meyer, and others for their review and input.

django/contrib/admin/migrations/0001_initial.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 
 from django.db import models, migrations
 from django.conf import settings
+import django.contrib.admin.models
 
 
 class Migration(migrations.Migration):
@@ -32,5 +33,8 @@ class Migration(migrations.Migration):
                 'verbose_name_plural': 'log entries',
             },
             bases=(models.Model,),
+            managers=[
+                ('objects', django.contrib.admin.models.LogEntryManager()),
+            ],
         ),
     ]

django/contrib/admin/models.py

@@ -15,6 +15,8 @@ DELETION = 3
 
 
 class LogEntryManager(models.Manager):
+    use_in_migrations = True
+
     def log_action(self, user_id, content_type_id, object_id, object_repr, action_flag, change_message=''):
         e = self.model(
             None, None, user_id, content_type_id, smart_text(object_id),

django/contrib/auth/migrations/0001_initial.py

@@ -4,6 +4,7 @@ from __future__ import unicode_literals
 from django.core import validators
 from django.db import models, migrations
 from django.utils import timezone
+import django.contrib.auth.models
 
 
 class Migration(migrations.Migration):
@@ -27,6 +28,9 @@ class Migration(migrations.Migration):
                 'verbose_name': 'permission',
                 'verbose_name_plural': 'permissions',
             },
+            managers=[
+                ('objects', django.contrib.auth.models.PermissionManager()),
+            ],
         ),
         migrations.CreateModel(
             name='Group',
@@ -39,6 +43,9 @@ class Migration(migrations.Migration):
                 'verbose_name': 'group',
                 'verbose_name_plural': 'groups',
             },
+            managers=[
+                ('objects', django.contrib.auth.models.GroupManager()),
+            ],
         ),
         migrations.CreateModel(
             name='User',
@@ -62,5 +69,8 @@ class Migration(migrations.Migration):
                 'verbose_name': 'user',
                 'verbose_name_plural': 'users',
             },
+            managers=[
+                ('objects', django.contrib.auth.models.UserManager()),
+            ],
         ),
     ]

django/contrib/auth/models.py

@@ -29,6 +29,8 @@ user_logged_in.connect(update_last_login)
 
 
 class PermissionManager(models.Manager):
+    use_in_migrations = True
+
     def get_by_natural_key(self, codename, app_label, model):
         return self.get(
             codename=codename,
@@ -87,6 +89,8 @@ class GroupManager(models.Manager):
     """
     The manager for the auth's Group model.
     """
+    use_in_migrations = True
+
     def get_by_natural_key(self, name):
         return self.get(name=name)
 
@@ -160,6 +164,7 @@ class BaseUserManager(models.Manager):
 
 
 class UserManager(BaseUserManager):
+    use_in_migrations = True
 
     def _create_user(self, username, email, password,
                      is_staff, is_superuser, **extra_fields):

django/contrib/contenttypes/migrations/0001_initial.py

@@ -2,6 +2,7 @@
 from __future__ import unicode_literals
 
 from django.db import models, migrations
+import django.contrib.contenttypes.models
 
 
 class Migration(migrations.Migration):
@@ -25,6 +26,9 @@ class Migration(migrations.Migration):
                 'verbose_name_plural': 'content types',
             },
             bases=(models.Model,),
+            managers=[
+                ('objects', django.contrib.contenttypes.models.ContentTypeManager()),
+            ],
         ),
         migrations.AlterUniqueTogether(
             name='contenttype',

django/contrib/contenttypes/models.py

@@ -9,6 +9,7 @@ from django.utils.encoding import python_2_unicode_compatible
 
 
 class ContentTypeManager(models.Manager):
+    use_in_migrations = True
 
     # Cache to avoid re-looking up ContentType objects all over the place.
     # This cache is shared by all the get_for_* methods.

django/contrib/sessions/migrations/0001_initial.py

@@ -2,6 +2,7 @@
 from __future__ import unicode_literals
 
 from django.db import models, migrations
+import django.contrib.sessions.models
 
 
 class Migration(migrations.Migration):
@@ -23,5 +24,8 @@ class Migration(migrations.Migration):
                 'verbose_name_plural': 'sessions',
             },
             bases=(models.Model,),
+            managers=[
+                ('objects', django.contrib.sessions.models.SessionManager()),
+            ],
         ),
     ]

django/contrib/sessions/models.py

@@ -6,6 +6,8 @@ from django.utils.translation import ugettext_lazy as _
 
 
 class SessionManager(models.Manager):
+    use_in_migrations = True
+
     def encode(self, session_dict):
         """
         Returns the given session dictionary serialized and encoded as a string.

django/contrib/sites/managers.py

@@ -10,6 +10,8 @@ from django.db.models.fields import FieldDoesNotExist
 class CurrentSiteManager(models.Manager):
     "Use this to limit objects to those associated with the current site."
 
+    use_in_migrations = True
+
     def __init__(self, field_name=None):
         super(CurrentSiteManager, self).__init__()
         self.__field_name = field_name

django/contrib/sites/migrations/0001_initial.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 
 from django.db import models, migrations
 from django.contrib.sites.models import _simple_domain_name_validator
+import django.contrib.sites.models
 
 
 class Migration(migrations.Migration):
@@ -24,5 +25,8 @@ class Migration(migrations.Migration):
                 'verbose_name_plural': 'sites',
             },
             bases=(models.Model,),
+            managers=[
+                ('objects', django.contrib.sites.models.SiteManager()),
+            ],
         ),
     ]

django/contrib/sites/models.py

@@ -33,6 +33,7 @@ def _simple_domain_name_validator(value):
 
 
 class SiteManager(models.Manager):
+    use_in_migrations = True
 
     def _get_site_by_id(self, site_id):
         if site_id not in SITE_CACHE:

django/db/migrations/autodetector.py

@@ -178,6 +178,7 @@ class MigrationAutodetector(object):
         self.generate_deleted_proxies()
         self.generate_created_proxies()
         self.generate_altered_options()
+        self.generate_altered_managers()
 
         # Generate field operations
         self.generate_renamed_fields()
@@ -503,6 +504,7 @@ class MigrationAutodetector(object):
                     fields=[d for d in model_state.fields if d[0] not in related_fields],
                     options=model_state.options,
                     bases=model_state.bases,
+                    managers=model_state.managers,
                 ),
                 dependencies=dependencies,
                 beginning=True,
@@ -607,6 +609,7 @@ class MigrationAutodetector(object):
                     fields=[],
                     options=model_state.options,
                     bases=model_state.bases,
+                    managers=model_state.managers,
                 ),
                 # Depend on the deletion of any possible non-proxy version of us
                 dependencies=dependencies,
@@ -990,6 +993,20 @@ class MigrationAutodetector(object):
                     dependencies=dependencies,
                 )
 
+    def generate_altered_managers(self):
+        for app_label, model_name in sorted(self.kept_model_keys):
+            old_model_name = self.renamed_models.get((app_label, model_name), model_name)
+            old_model_state = self.from_state.models[app_label, old_model_name]
+            new_model_state = self.to_state.models[app_label, model_name]
+            if old_model_state.managers != new_model_state.managers:
+                self.add_operation(
+                    app_label,
+                    operations.AlterModelManagers(
+                        name=model_name,
+                        managers=new_model_state.managers,
+                    )
+                )
+
     def arrange_for_graph(self, changes, graph, migration_name=None):
         """
         Takes in a result from changes() and a MigrationGraph,

django/db/migrations/operations/__init__.py

@@ -1,6 +1,6 @@
 from .models import (CreateModel, DeleteModel, AlterModelTable,
     AlterUniqueTogether, AlterIndexTogether, RenameModel, AlterModelOptions,
-    AlterOrderWithRespectTo)
+    AlterOrderWithRespectTo, AlterModelManagers)
 from .fields import AddField, RemoveField, AlterField, RenameField
 from .special import SeparateDatabaseAndState, RunSQL, RunPython
 
@@ -9,5 +9,5 @@ __all__ = [
     'RenameModel', 'AlterIndexTogether', 'AlterModelOptions',
     'AddField', 'RemoveField', 'AlterField', 'RenameField',
     'SeparateDatabaseAndState', 'RunSQL', 'RunPython',
-    'AlterOrderWithRespectTo',
+    'AlterOrderWithRespectTo', 'AlterModelManagers',
 ]

django/db/migrations/operations/models.py

@@ -12,13 +12,14 @@ class CreateModel(Operation):
     Create a model's table.
     """
 
-    serialization_expand_args = ['fields', 'options']
+    serialization_expand_args = ['fields', 'options', 'managers']
 
-    def __init__(self, name, fields, options=None, bases=None):
+    def __init__(self, name, fields, options=None, bases=None, managers=None):
         self.name = name
         self.fields = fields
         self.options = options or {}
         self.bases = bases or (models.Model,)
+        self.managers = managers or []
 
     def deconstruct(self):
         kwargs = {
@@ -29,6 +30,8 @@ class CreateModel(Operation):
             kwargs['options'] = self.options
         if self.bases and self.bases != (models.Model,):
             kwargs['bases'] = self.bases
+        if self.managers and self.managers != [('objects', models.Manager())]:
+            kwargs['managers'] = self.managers
         return (
             self.__class__.__name__,
             [],
@@ -42,6 +45,7 @@ class CreateModel(Operation):
             list(self.fields),
             dict(self.options),
             tuple(self.bases),
+            list(self.managers),
         )
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):
@@ -467,3 +471,38 @@ class AlterModelOptions(Operation):
 
     def describe(self):
         return "Change Meta options on %s" % (self.name, )
+
+
+class AlterModelManagers(Operation):
+    """
+    Alters the model's managers
+    """
+
+    serialization_expand_args = ['managers']
+
+    def __init__(self, name, managers):
+        self.name = name
+        self.managers = managers
+
+    def deconstruct(self):
+        return (
+            self.__class__.__name__,
+            [self.name, self.managers],
+            {}
+        )
+
+    def state_forwards(self, app_label, state):
+        model_state = state.models[app_label, self.name.lower()]
+        model_state.managers = list(self.managers)
+
+    def database_forwards(self, app_label, schema_editor, from_state, to_state):
+        pass
+
+    def database_backwards(self, app_label, schema_editor, from_state, to_state):
+        pass
+
+    def references_model(self, name, app_label=None):
+        return name.lower() == self.name.lower()
+
+    def describe(self):
+        return "Change managers on %s" % (self.name, )

django/db/migrations/state.py

@@ -149,12 +149,13 @@ class ModelState(object):
     assign new ones, as these are not detached during a clone.
     """
 
-    def __init__(self, app_label, name, fields, options=None, bases=None):
+    def __init__(self, app_label, name, fields, options=None, bases=None, managers=None):
         self.app_label = app_label
         self.name = force_text(name)
         self.fields = fields
         self.options = options or {}
         self.bases = bases or (models.Model, )
+        self.managers = managers or []
         # Sanity-check that fields is NOT a dict. It must be ordered.
         if isinstance(self.fields, dict):
             raise ValueError("ModelState.fields cannot be a dict - it must be a list of 2-tuples.")
@@ -252,12 +253,51 @@ class ModelState(object):
         # Ensure at least one base inherits from models.Model
         if not any((isinstance(base, six.string_types) or issubclass(base, models.Model)) for base in bases):
             bases = (models.Model,)
+
+        # Constructs all managers on the model
+        managers = {}
+
+        def reconstruct_manager(mgr):
+            as_manager, manager_path, qs_path, args, kwargs = mgr.deconstruct()
+            if as_manager:
+                qs_class = import_string(qs_path)
+                instance = qs_class.as_manager()
+            else:
+                manager_class = import_string(manager_path)
+                instance = manager_class(*args, **kwargs)
+            # We rely on the ordering of the creation_counter of the original
+            # instance
+            managers[mgr.name] = (mgr.creation_counter, instance)
+
+        default_manager_name = model._default_manager.name
+        # Make sure the default manager is always the first
+        if model._default_manager.use_in_migrations:
+            reconstruct_manager(model._default_manager)
+        else:
+            # Force this manager to be the first and thus default
+            managers[default_manager_name] = (0, models.Manager())
+        # Sort all managers by their creation counter
+        for _, manager, _ in sorted(model._meta.managers):
+            if manager.name == '_base_manager' or not manager.use_in_migrations:
+                continue
+            reconstruct_manager(manager)
+        # Sort all managers by their creation counter but take only name and
+        # instance for further processing
+        managers = [
+            (name, instance) for name, (cc, instance) in
+            sorted(managers.items(), key=lambda v: v[1])
+        ]
+        if managers == [(default_manager_name, models.Manager())]:
+            managers = []
+
+        # Construct the new ModelState
         return cls(
             model._meta.app_label,
             model._meta.object_name,
             fields,
             options,
             bases,
+            managers,
         )
 
     @classmethod
@@ -292,6 +332,7 @@ class ModelState(object):
             fields=list(self.construct_fields()),
             options=dict(self.options),
             bases=self.bases,
+            managers=self.managers,
         )
 
     def render(self, apps):
@@ -312,6 +353,11 @@ class ModelState(object):
         body = dict(self.construct_fields())
         body['Meta'] = meta
         body['__module__'] = "__fake__"
+
+        # Restore managers
+        for mgr_name, manager in self.managers:
+            body[mgr_name] = manager
+
         # Then, make a Model object
         return type(
             str(self.name),
@@ -336,7 +382,8 @@ class ModelState(object):
             all((k1 == k2 and (f1.deconstruct()[1:] == f2.deconstruct()[1:]))
                 for (k1, f1), (k2, f2) in zip(self.fields, other.fields)) and
             (self.options == other.options) and
-            (self.bases == other.bases)
+            (self.bases == other.bases) and
+            (self.managers == other.managers)
         )
 
     def __ne__(self, other):

django/db/migrations/writer.py

@@ -223,13 +223,7 @@ class MigrationWriter(object):
 
     @classmethod
     def serialize_deconstructed(cls, path, args, kwargs):
-        module, name = path.rsplit(".", 1)
-        if module == "django.db.models":
-            imports = {"from django.db import models"}
-            name = "models.%s" % name
-        else:
-            imports = {"import %s" % module}
-            name = path
+        name, imports = cls._serialize_path(path)
         strings = []
         for arg in args:
             arg_string, arg_imports = cls.serialize(arg)
@@ -241,6 +235,17 @@ class MigrationWriter(object):
             strings.append("%s=%s" % (kw, arg_string))
         return "%s(%s)" % (name, ", ".join(strings)), imports
 
+    @classmethod
+    def _serialize_path(cls, path):
+        module, name = path.rsplit(".", 1)
+        if module == "django.db.models":
+            imports = {"from django.db import models"}
+            name = "models.%s" % name
+        else:
+            imports = {"import %s" % module}
+            name = path
+        return name, imports
+
     @classmethod
     def serialize(cls, value):
         """
@@ -344,6 +349,13 @@ class MigrationWriter(object):
                     return value.__name__, set()
                 else:
                     return "%s.%s" % (module, value.__name__), {"import %s" % module}
+        elif isinstance(value, models.manager.BaseManager):
+            as_manager, manager_path, qs_path, args, kwargs = value.deconstruct()
+            if as_manager:
+                name, imports = cls._serialize_path(qs_path)
+                return "%s.as_manager()" % name, imports
+            else:
+                return cls.serialize_deconstructed(manager_path, args, kwargs)
         # Anything that knows how to deconstruct itself.
         elif hasattr(value, 'deconstruct'):
             return cls.serialize_deconstructed(*value.deconstruct())

django/db/models/manager.py

@@ -1,4 +1,5 @@
 import copy
+from importlib import import_module
 import inspect
 
 from django.db import router
@@ -58,6 +59,16 @@ class BaseManager(object):
     # Tracks each time a Manager instance is created. Used to retain order.
     creation_counter = 0
 
+    #: If set to True the manager will be serialized into migrations and will
+    #: thus be available in e.g. RunPython operations
+    use_in_migrations = False
+
+    def __new__(cls, *args, **kwargs):
+        # We capture the arguments to make returning them trivial
+        obj = super(BaseManager, cls).__new__(cls)
+        obj._constructor_args = (args, kwargs)
+        return obj
+
     def __init__(self):
         super(BaseManager, self).__init__()
         self._set_creation_counter()
@@ -73,6 +84,43 @@ class BaseManager(object):
         app = model._meta.app_label
         return '%s.%s.%s' % (app, model._meta.object_name, self.name)
 
+    def deconstruct(self):
+        """
+        Returns a 5-tuple of the form (as_manager (True), manager_class,
+        queryset_class, args, kwargs).
+
+        Raises a ValueError if the manager is dynamically generated.
+        """
+        qs_class = self._queryset_class
+        if getattr(self, '_built_as_manager', False):
+            # using MyQuerySet.as_manager()
+            return (
+                True,  # as_manager
+                None,  # manager_class
+                '%s.%s' % (qs_class.__module__, qs_class.__name__),  # qs_class
+                None,  # args
+                None,  # kwargs
+            )
+        else:
+            module_name = self.__module__
+            name = self.__class__.__name__
+            # Make sure it's actually there and not an inner class
+            module = import_module(module_name)
+            if not hasattr(module, name):
+                raise ValueError(
+                    "Could not find manager %s in %s.\n"
+                    "Please note that you need to inherit from managers you "
+                    "dynamically generated with 'from_queryset()'."
+                    % (name, module_name)
+                )
+            return (
+                False,  # as_manager
+                '%s.%s' % (module_name, name),  # manager_class
+                None,  # qs_class
+                self._constructor_args[0],  # args
+                self._constructor_args[1],  # kwargs
+            )
+
     def check(self, **kwargs):
         return []
 
@@ -183,6 +231,15 @@ class BaseManager(object):
         # understanding of how this comes into play.
         return self.get_queryset()
 
+    def __eq__(self, other):
+        return (
+            isinstance(other, self.__class__) and
+            self._constructor_args == other._constructor_args
+        )
+
+    def __ne__(self, other):
+        return not (self == other)
+
 
 class Manager(BaseManager.from_queryset(QuerySet)):
     pass

django/db/models/query.py

@@ -67,7 +67,9 @@ class QuerySet(object):
     def as_manager(cls):
         # Address the circular dependency between `Queryset` and `Manager`.
         from django.db.models.manager import Manager
-        return Manager.from_queryset(cls)()
+        manager = Manager.from_queryset(cls)()
+        manager._built_as_manager = True
+        return manager
     as_manager.queryset_only = True
     as_manager = classmethod(as_manager)
 

docs/ref/migration-operations.txt

@@ -37,7 +37,7 @@ Schema Operations
 CreateModel
 -----------
 
-.. class:: CreateModel(name, fields, options=None, bases=None)
+.. class:: CreateModel(name, fields, options=None, bases=None, managers=None)
 
 Creates a new model in the project history and a corresponding table in the
 database to match it.
@@ -56,6 +56,14 @@ it can contain both class objects as well as strings in the format
 from the historical version). If it's not supplied, it defaults to just
 inheriting from the standard ``models.Model``.
 
+``managers`` takes a list of 2-tuples of ``(manager_name, manager_instance)``.
+The first manager in the list will be the default manager for this model during
+migrations.
+
+.. versionchanged:: 1.8
+
+    The ``managers`` argument was added.
+
 DeleteModel
 -----------
 
@@ -121,6 +129,15 @@ like ``permissions`` and ``verbose_name``. Does not affect the database, but
 persists these changes for :class:`RunPython` instances to use. ``options``
 should be a dictionary mapping option names to values.
 
+AlterModelManagers
+------------------
+
+.. versionadded:: 1.8
+
+.. class:: AlterModelManagers(name, managers)
+
+Alters the managers that are available during migrations.
+
 AddField
 --------
 

docs/releases/1.8.txt

@@ -387,6 +387,9 @@ Migrations
 * It is now possible to have migrations (most probably :ref:`data migrations
   <data-migrations>`) for applications without models.
 
+* Migrations can now :ref:`serialize model managers
+  <using-managers-in-migrations>` as part of the model state.
+
 Models
 ^^^^^^
 

docs/topics/migrations.txt

@@ -286,6 +286,36 @@ modified ``__init__`` method with the old signature. So if you need a new
 argument, please create a keyword argument and add something like
 ``assert kwargs.get('argument_name') is not None`` in the constructor.
 
+.. _using-managers-in-migrations:
+
+Model managers
+~~~~~~~~~~~~~~
+
+.. versionadded:: 1.8
+
+You can optionally serialize managers into migrations and have them available
+in :class:`~django.db.migrations.operations.RunPython` operations. This is done
+by defining a ``use_in_migrations`` attribute on the manager class::
+
+    class MyManager(models.Manager):
+        use_in_migrations = True
+
+    class MyModel(models.Model):
+        objects = MyManager()
+
+If you are using the :meth:`~django.db.models.from_queryset` function to
+dynamically generate a manager class, you need to inherit from the generated
+class to make it importable::
+
+    class MyManager(MyBaseManager.from_queryset(CustomQuerySet)):
+        use_in_migrations = True
+
+    class MyModel(models.Model):
+        objects = MyManager()
+
+Please refer to the notes about :ref:`historical-models` in migrations to see
+the implications that come along.
+
 Adding migrations to apps
 -------------------------
 
@@ -326,16 +356,17 @@ you can use the :djadminopt:`--name` option::
 Historical models
 -----------------
 
-When you run migrations, Django is working from historical versions of
-your models stored in the migration files. If you write Python code
-using the :class:`~django.db.migrations.operations.RunPython` operation, or if
-you have ``allow_migrate`` methods on your database routers, you will be
-exposed to these versions of your models.
+When you run migrations, Django is working from historical versions of your
+models stored in the migration files. If you write Python code using the
+:class:`~django.db.migrations.operations.RunPython` operation, or if you have
+``allow_migrate`` methods on your database routers, you will be exposed to
+these versions of your models.
 
 Because it's impossible to serialize arbitrary Python code, these historical
-models will not have any custom methods or managers that you have defined.
-They will, however, have the same fields, relationships and ``Meta`` options
-(also versioned, so they may be different from your current ones).
+models will not have any custom methods that you have defined. They will,
+however, have the same fields, relationships, managers (limited to those with
+``use_in_migrations = True``) and ``Meta`` options (also versioned, so they may
+be different from your current ones).
 
 .. warning::
 
@@ -344,16 +375,17 @@ They will, however, have the same fields, relationships and ``Meta`` options
   constructors or instance methods. Plan appropriately!
 
 References to functions in field options such as ``upload_to`` and
-``limit_choices_to`` are serialized in migrations, so the functions will need
-to be kept around for as long as there is a migration referencing them. Any
-:doc:`custom model fields </howto/custom-model-fields>` will also need to be
-kept, since these are imported directly by migrations.
-
-In addition, the base classes of the model are just stored as pointers,
-so you must always keep base classes around for as long as there is a migration
-that contains a reference to them. On the plus side, methods and managers
-from these base classes inherit normally, so if you absolutely need access
-to these you can opt to move them into a superclass.
+``limit_choices_to`` and model manager declarations with managers having
+``use_in_migrations = True`` are serialized in migrations, so the functions and
+classes will need to be kept around for as long as there is a migration
+referencing them. Any :doc:`custom model fields </howto/custom-model-fields>`
+will also need to be kept, since these are imported directly by migrations.
+
+In addition, the base classes of the model are just stored as pointers, so you
+must always keep base classes around for as long as there is a migration that
+contains a reference to them. On the plus side, methods and managers from these
+base classes inherit normally, so if you absolutely need access to these you
+can opt to move them into a superclass.
 
 .. _data-migrations:
 

tests/custom_managers/models.py

@@ -60,9 +60,16 @@ class BaseCustomManager(models.Manager):
     def manager_only(self):
         return self.all()
 
+
 CustomManager = BaseCustomManager.from_queryset(CustomQuerySet)
 
 
+class DeconstructibleCustomManager(BaseCustomManager.from_queryset(CustomQuerySet)):
+
+    def __init__(self, a, b, c=1, d=2):
+        super(DeconstructibleCustomManager, self).__init__(a)
+
+
 class FunPeopleManager(models.Manager):
     def get_queryset(self):
         return super(FunPeopleManager, self).get_queryset().filter(fun=True)

tests/custom_managers/tests.py

@@ -1,9 +1,11 @@
 from __future__ import unicode_literals
 
+from django.db import models
 from django.test import TestCase
 from django.utils import six
 
-from .models import (Book, Car, FunPerson, OneToOneRestrictedModel, Person,
+from .models import (Book, Car, CustomManager, CustomQuerySet,
+    DeconstructibleCustomManager, FunPerson, OneToOneRestrictedModel, Person,
     PersonManager, PublishedBookManager, RelatedModel, RestrictedModel)
 
 
@@ -470,6 +472,44 @@ class CustomManagerTests(TestCase):
             ordered=False,
         )
 
+    def test_deconstruct_default(self):
+        mgr = models.Manager()
+        as_manager, mgr_path, qs_path, args, kwargs = mgr.deconstruct()
+        self.assertFalse(as_manager)
+        self.assertEqual(mgr_path, 'django.db.models.manager.Manager')
+        self.assertEqual(args, ())
+        self.assertEqual(kwargs, {})
+
+    def test_deconstruct_as_manager(self):
+        mgr = CustomQuerySet.as_manager()
+        as_manager, mgr_path, qs_path, args, kwargs = mgr.deconstruct()
+        self.assertTrue(as_manager)
+        self.assertEqual(qs_path, 'custom_managers.models.CustomQuerySet')
+
+    def test_deconstruct_from_queryset(self):
+        mgr = DeconstructibleCustomManager('a', 'b')
+        as_manager, mgr_path, qs_path, args, kwargs = mgr.deconstruct()
+        self.assertFalse(as_manager)
+        self.assertEqual(mgr_path, 'custom_managers.models.DeconstructibleCustomManager')
+        self.assertEqual(args, ('a', 'b',))
+        self.assertEqual(kwargs, {})
+
+        mgr = DeconstructibleCustomManager('x', 'y', c=3, d=4)
+        as_manager, mgr_path, qs_path, args, kwargs = mgr.deconstruct()
+        self.assertFalse(as_manager)
+        self.assertEqual(mgr_path, 'custom_managers.models.DeconstructibleCustomManager')
+        self.assertEqual(args, ('x', 'y',))
+        self.assertEqual(kwargs, {'c': 3, 'd': 4})
+
+    def test_deconstruct_from_queryset_failing(self):
+        mgr = CustomManager('arg')
+        msg = ("Could not find manager BaseCustomManagerFromCustomQuerySet in "
+               "django.db.models.manager.\n"
+               "Please note that you need to inherit from managers you "
+               "dynamically generated with 'from_queryset()'.")
+        with self.assertRaisesMessage(ValueError, msg):
+            mgr.deconstruct()
+
 
 class TestCars(TestCase):
 

tests/migrations/models.py

@@ -50,3 +50,21 @@ class UnmigratedModel(models.Model):
     if its migrations directory has not been repointed)
     """
     pass
+
+
+class FoodQuerySet(models.query.QuerySet):
+    pass
+
+
+class BaseFoodManager(models.Manager):
+    def __init__(self, a, b, c=1, d=2):
+        super(BaseFoodManager, self).__init__()
+        self.args = (a, b, c, d)
+
+
+class FoodManager(BaseFoodManager.from_queryset(FoodQuerySet)):
+    use_in_migrations = True
+
+
+class NoMigrationFoodManager(BaseFoodManager.from_queryset(FoodQuerySet)):
+    pass

tests/migrations/test_autodetector.py

@@ -9,6 +9,8 @@ from django.db.migrations.loader import MigrationLoader
 from django.db import models, connection
 from django.contrib.auth.models import AbstractBaseUser
 
+from .models import FoodManager, FoodQuerySet
+
 
 class DeconstructableObject(object):
     """
@@ -159,6 +161,13 @@ class AutodetectorTests(TestCase):
     other_pony = ModelState("otherapp", "Pony", [
         ("id", models.AutoField(primary_key=True)),
     ])
+    other_pony_food = ModelState("otherapp", "Pony", [
+        ("id", models.AutoField(primary_key=True)),
+    ], managers=[
+        ('food_qs', FoodQuerySet.as_manager()),
+        ('food_mgr', FoodManager('a', 'b')),
+        ('food_mgr_kwargs', FoodManager('x', 'y', 3, 4)),
+    ])
     other_stable = ModelState("otherapp", "Stable", [("id", models.AutoField(primary_key=True))])
     third_thing = ModelState("thirdapp", "Thing", [("id", models.AutoField(primary_key=True))])
     book = ModelState("otherapp", "Book", [
@@ -456,13 +465,15 @@ class AutodetectorTests(TestCase):
         """Tests autodetection of new models."""
         # Make state
         before = self.make_project_state([])
-        after = self.make_project_state([self.author_empty])
+        after = self.make_project_state([self.other_pony_food])
         autodetector = MigrationAutodetector(before, after)
         changes = autodetector._detect_changes()
         # Right number/type of migrations?
-        self.assertNumberMigrations(changes, 'testapp', 1)
-        self.assertOperationTypes(changes, 'testapp', 0, ["CreateModel"])
-        self.assertOperationAttributes(changes, "testapp", 0, 0, name="Author")
+        self.assertNumberMigrations(changes, 'otherapp', 1)
+        self.assertOperationTypes(changes, 'otherapp', 0, ["CreateModel"])
+        self.assertOperationAttributes(changes, "otherapp", 0, 0, name="Pony")
+        self.assertEqual([name for name, mgr in changes['otherapp'][0].operations[0].managers],
+                         ['food_qs', 'food_mgr', 'food_mgr_kwargs'])
 
     def test_old_model(self):
         """Tests deletion of old models."""
@@ -1406,6 +1417,24 @@ class AutodetectorTests(TestCase):
         self.assertOperationAttributes(changes, 'testapp', 0, 1, name="author", order_with_respect_to="book")
         self.assertNotIn("_order", [name for name, field in changes['testapp'][0].operations[0].fields])
 
+    def test_alter_model_managers(self):
+        """
+        Tests that changing the model managers adds a new operation.
+        """
+        # Make state
+        before = self.make_project_state([self.other_pony])
+        after = self.make_project_state([self.other_pony_food])
+        autodetector = MigrationAutodetector(before, after)
+        changes = autodetector._detect_changes()
+        # Right number/type of migrations?
+        self.assertNumberMigrations(changes, 'otherapp', 1)
+        self.assertOperationTypes(changes, 'otherapp', 0, ["AlterModelManagers"])
+        self.assertOperationAttributes(changes, 'otherapp', 0, 0, name="pony")
+        self.assertEqual([name for name, mgr in changes['otherapp'][0].operations[0].managers],
+                         ['food_qs', 'food_mgr', 'food_mgr_kwargs'])
+        self.assertEqual(changes['otherapp'][0].operations[0].managers[1][1].args, ('a', 'b', 1, 2))
+        self.assertEqual(changes['otherapp'][0].operations[0].managers[2][1].args, ('x', 'y', 3, 4))
+
     def test_swappable_first_inheritance(self):
         """Tests that swappable models get their CreateModel first."""
         # Make state

tests/migrations/test_operations.py

@@ -17,6 +17,7 @@ from django.db.utils import IntegrityError, DatabaseError
 from django.test import override_settings
 from django.utils import six
 
+from .models import FoodManager, FoodQuerySet
 from .test_base import MigrationTestBase
 
 
@@ -48,7 +49,7 @@ class OperationTestBase(MigrationTestBase):
         return project_state, new_state
 
     def set_up_test_model(self, app_label, second_model=False, third_model=False,
-            related_model=False, mti_model=False, proxy_model=False,
+            related_model=False, mti_model=False, proxy_model=False, manager_model=False,
             unique_together=False, options=False, db_table=None, index_together=False):
         """
         Creates a test model state and database table.
@@ -142,6 +143,18 @@ class OperationTestBase(MigrationTestBase):
                 options={"proxy": True},
                 bases=['%s.Pony' % app_label],
             ))
+        if manager_model:
+            operations.append(migrations.CreateModel(
+                "Food",
+                fields=[
+                    ("id", models.AutoField(primary_key=True)),
+                ],
+                managers=[
+                    ("food_qs", FoodQuerySet.as_manager()),
+                    ("food_mgr", FoodManager("a", "b")),
+                    ("food_mgr_kwargs", FoodManager("x", "y", 3, 4)),
+                ]
+            ))
 
         return self.apply_operations(app_label, ProjectState(), operations)
 
@@ -186,6 +199,10 @@ class OperationTests(OperationTestBase):
         self.assertEqual(definition[0], "CreateModel")
         self.assertEqual(definition[1], [])
         self.assertEqual(sorted(definition[2].keys()), ["fields", "name"])
+        # And default manager not in set
+        operation = migrations.CreateModel("Foo", fields=[], managers=[("objects", models.Manager())])
+        definition = operation.deconstruct()
+        self.assertNotIn('managers', definition[2])
 
     def test_create_model_with_unique_after(self):
         """
@@ -365,6 +382,37 @@ class OperationTests(OperationTestBase):
         self.assertTableNotExists("test_crummo_unmanagedpony")
         self.assertTableExists("test_crummo_pony")
 
+    def test_create_model_managers(self):
+        """
+        Tests that the managers on a model are set.
+        """
+        project_state = self.set_up_test_model("test_cmoma")
+        # Test the state alteration
+        operation = migrations.CreateModel(
+            "Food",
+            fields=[
+                ("id", models.AutoField(primary_key=True)),
+            ],
+            managers=[
+                ("food_qs", FoodQuerySet.as_manager()),
+                ("food_mgr", FoodManager("a", "b")),
+                ("food_mgr_kwargs", FoodManager("x", "y", 3, 4)),
+            ]
+        )
+        self.assertEqual(operation.describe(), "Create model Food")
+        new_state = project_state.clone()
+        operation.state_forwards("test_cmoma", new_state)
+        self.assertIn(("test_cmoma", "food"), new_state.models)
+        managers = new_state.models["test_cmoma", "food"].managers
+        self.assertEqual(managers[0][0], "food_qs")
+        self.assertIsInstance(managers[0][1], models.Manager)
+        self.assertEqual(managers[1][0], "food_mgr")
+        self.assertIsInstance(managers[1][1], FoodManager)
+        self.assertEqual(managers[1][1].args, ("a", "b", 1, 2))
+        self.assertEqual(managers[2][0], "food_mgr_kwargs")
+        self.assertIsInstance(managers[2][1], FoodManager)
+        self.assertEqual(managers[2][1].args, ("x", "y", 3, 4))
+
     def test_delete_model(self):
         """
         Tests the DeleteModel operation.
@@ -1208,6 +1256,61 @@ class OperationTests(OperationTestBase):
         self.assertEqual(definition[1], [])
         self.assertEqual(definition[2], {'name': "Rider", 'order_with_respect_to': "pony"})
 
+    def test_alter_model_managers(self):
+        """
+        Tests that the managers on a model are set.
+        """
+        project_state = self.set_up_test_model("test_almoma")
+        # Test the state alteration
+        operation = migrations.AlterModelManagers(
+            "Pony",
+            managers=[
+                ("food_qs", FoodQuerySet.as_manager()),
+                ("food_mgr", FoodManager("a", "b")),
+                ("food_mgr_kwargs", FoodManager("x", "y", 3, 4)),
+            ]
+        )
+        self.assertEqual(operation.describe(), "Change managers on Pony")
+        managers = project_state.models["test_almoma", "pony"].managers
+        self.assertEqual(managers, [])
+
+        new_state = project_state.clone()
+        operation.state_forwards("test_almoma", new_state)
+        self.assertIn(("test_almoma", "pony"), new_state.models)
+        managers = new_state.models["test_almoma", "pony"].managers
+        self.assertEqual(managers[0][0], "food_qs")
+        self.assertIsInstance(managers[0][1], models.Manager)
+        self.assertEqual(managers[1][0], "food_mgr")
+        self.assertIsInstance(managers[1][1], FoodManager)
+        self.assertEqual(managers[1][1].args, ("a", "b", 1, 2))
+        self.assertEqual(managers[2][0], "food_mgr_kwargs")
+        self.assertIsInstance(managers[2][1], FoodManager)
+        self.assertEqual(managers[2][1].args, ("x", "y", 3, 4))
+
+    def test_alter_model_managers_emptying(self):
+        """
+        Tests that the managers on a model are set.
+        """
+        project_state = self.set_up_test_model("test_almomae", manager_model=True)
+        # Test the state alteration
+        operation = migrations.AlterModelManagers("Food", managers=[])
+        self.assertEqual(operation.describe(), "Change managers on Food")
+        self.assertIn(("test_almomae", "food"), project_state.models)
+        managers = project_state.models["test_almomae", "food"].managers
+        self.assertEqual(managers[0][0], "food_qs")
+        self.assertIsInstance(managers[0][1], models.Manager)
+        self.assertEqual(managers[1][0], "food_mgr")
+        self.assertIsInstance(managers[1][1], FoodManager)
+        self.assertEqual(managers[1][1].args, ("a", "b", 1, 2))
+        self.assertEqual(managers[2][0], "food_mgr_kwargs")
+        self.assertIsInstance(managers[2][1], FoodManager)
+        self.assertEqual(managers[2][1].args, ("x", "y", 3, 4))
+
+        new_state = project_state.clone()
+        operation.state_forwards("test_almomae", new_state)
+        managers = new_state.models["test_almomae", "food"].managers
+        self.assertEqual(managers, [])
+
     def test_alter_fk(self):
         """
         Tests that creating and then altering an FK works correctly

tests/migrations/test_state.py

@@ -3,7 +3,8 @@ from django.db import models
 from django.db.migrations.state import ProjectState, ModelState, InvalidBasesError
 from django.test import TestCase
 
-from .models import ModelWithCustomBase
+from .models import (FoodManager, FoodQuerySet, ModelWithCustomBase,
+    NoMigrationFoodManager)
 
 
 class StateTests(TestCase):
@@ -54,11 +55,56 @@ class StateTests(TestCase):
                 verbose_name = "tome"
                 db_table = "test_tome"
 
+        class Food(models.Model):
+
+            food_mgr = FoodManager('a', 'b')
+            food_qs = FoodQuerySet.as_manager()
+            food_no_mgr = NoMigrationFoodManager('x', 'y')
+
+            class Meta:
+                app_label = "migrations"
+                apps = new_apps
+
+        class FoodNoManagers(models.Model):
+
+            class Meta:
+                app_label = "migrations"
+                apps = new_apps
+
+        class FoodNoDefaultManager(models.Model):
+
+            food_no_mgr = NoMigrationFoodManager('x', 'y')
+            food_mgr = FoodManager('a', 'b')
+            food_qs = FoodQuerySet.as_manager()
+
+            class Meta:
+                app_label = "migrations"
+                apps = new_apps
+
+        mgr1 = FoodManager('a', 'b')
+        mgr2 = FoodManager('x', 'y', c=3, d=4)
+
+        class FoodOrderedManagers(models.Model):
+            # The managers on this model should be orderd by their creation
+            # counter and not by the order in model body
+
+            food_no_mgr = NoMigrationFoodManager('x', 'y')
+            food_mgr2 = mgr2
+            food_mgr1 = mgr1
+
+            class Meta:
+                app_label = "migrations"
+                apps = new_apps
+
         project_state = ProjectState.from_apps(new_apps)
         author_state = project_state.models['migrations', 'author']
         author_proxy_state = project_state.models['migrations', 'authorproxy']
         sub_author_state = project_state.models['migrations', 'subauthor']
         book_state = project_state.models['migrations', 'book']
+        food_state = project_state.models['migrations', 'food']
+        food_no_managers_state = project_state.models['migrations', 'foodnomanagers']
+        food_no_default_manager_state = project_state.models['migrations', 'foodnodefaultmanager']
+        food_order_manager_state = project_state.models['migrations', 'foodorderedmanagers']
 
         self.assertEqual(author_state.app_label, "migrations")
         self.assertEqual(author_state.name, "Author")
@@ -89,26 +135,43 @@ class StateTests(TestCase):
         self.assertEqual(len(sub_author_state.fields), 2)
         self.assertEqual(sub_author_state.bases, ("migrations.author", ))
 
+        # The default manager is used in migrations
+        self.assertEqual([name for name, mgr in food_state.managers], ['food_mgr'])
+        self.assertEqual(food_state.managers[0][1].args, ('a', 'b', 1, 2))
+
+        # No explicit managers defined. Migrations will fall back to the default
+        self.assertEqual(food_no_managers_state.managers, [])
+
+        # food_mgr is used in migration but isn't the default mgr, hence add the
+        # default
+        self.assertEqual([name for name, mgr in food_no_default_manager_state.managers],
+                         ['food_no_mgr', 'food_mgr'])
+        self.assertEqual(food_no_default_manager_state.managers[0][1].__class__, models.Manager)
+        self.assertIsInstance(food_no_default_manager_state.managers[1][1], FoodManager)
+
+        self.assertEqual([name for name, mgr in food_order_manager_state.managers],
+                         ['food_mgr1', 'food_mgr2'])
+        self.assertEqual([mgr.args for name, mgr in food_order_manager_state.managers],
+                         [('a', 'b', 1, 2), ('x', 'y', 3, 4)])
+
     def test_render(self):
         """
         Tests rendering a ProjectState into an Apps.
         """
         project_state = ProjectState()
         project_state.add_model_state(ModelState(
-            "migrations",
-            "Tag",
-            [
+            app_label="migrations",
+            name="Tag",
+            fields=[
                 ("id", models.AutoField(primary_key=True)),
                 ("name", models.CharField(max_length=100)),
                 ("hidden", models.BooleanField()),
             ],
-            {},
-            None,
         ))
         project_state.add_model_state(ModelState(
-            "migrations",
-            "SubTag",
-            [
+            app_label="migrations",
+            name="SubTag",
+            fields=[
                 ('tag_ptr', models.OneToOneField(
                     auto_created=True,
                     primary_key=True,
@@ -118,15 +181,40 @@ class StateTests(TestCase):
                 )),
                 ("awesome", models.BooleanField()),
             ],
-            options={},
             bases=("migrations.Tag",),
         ))
 
+        base_mgr = models.Manager()
+        mgr1 = FoodManager('a', 'b')
+        mgr2 = FoodManager('x', 'y', c=3, d=4)
+        project_state.add_model_state(ModelState(
+            app_label="migrations",
+            name="Food",
+            fields=[
+                ("id", models.AutoField(primary_key=True)),
+            ],
+            managers=[
+                # The ordering we really want is objects, mgr1, mgr2
+                ('default', base_mgr),
+                ('food_mgr2', mgr2),
+                ('food_mgr1', mgr1),
+            ]
+        ))
+
         new_apps = project_state.render()
         self.assertEqual(new_apps.get_model("migrations", "Tag")._meta.get_field_by_name("name")[0].max_length, 100)
         self.assertEqual(new_apps.get_model("migrations", "Tag")._meta.get_field_by_name("hidden")[0].null, False)
+
         self.assertEqual(len(new_apps.get_model("migrations", "SubTag")._meta.local_fields), 2)
 
+        Food = new_apps.get_model("migrations", "Food")
+        managers = sorted(Food._meta.managers)
+        self.assertEqual([mgr.name for _, mgr, _ in managers],
+                         ['default', 'food_mgr1', 'food_mgr2'])
+        self.assertEqual([mgr.__class__ for _, mgr, _ in managers],
+                         [models.Manager, FoodManager, FoodManager])
+        self.assertIs(managers[0][1], Food._default_manager)
+
     def test_render_model_inheritance(self):
         class Book(models.Model):
             title = models.CharField(max_length=1000)

tests/migrations/test_writer.py

@@ -19,6 +19,7 @@ from django.utils.deconstruct import deconstructible
 from django.utils.translation import ugettext_lazy as _
 from django.utils.timezone import get_default_timezone, utc, FixedOffset
 
+from custom_managers import models as custom_manager_models
 import custom_migration_operations.operations
 import custom_migration_operations.more_operations
 
@@ -351,3 +352,12 @@ class WriterTests(TestCase):
 
         string = MigrationWriter.serialize(models.CharField(default=DeconstructableInstances))[0]
         self.assertEqual(string, "models.CharField(default=migrations.test_writer.DeconstructableInstances)")
+
+    def test_serialize_managers(self):
+        self.assertSerializedEqual(models.Manager())
+        self.assertSerializedResultEqual(
+            custom_manager_models.CustomQuerySet.as_manager(),
+            ('custom_managers.models.CustomQuerySet.as_manager()', {'import custom_managers.models'})
+        )
+        self.assertSerializedEqual(custom_manager_models.DeconstructibleCustomManager('a', 'b'))
+        self.assertSerializedEqual(custom_manager_models.DeconstructibleCustomManager('x', 'y', c=3, d=4))