[soc2010/app-loading] re-adding files after failed dcommit

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2010/app-loading@13496 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/apps.py

@@ -1,12 +1,299 @@
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.datastructures import SortedDict
+from django.utils.importlib import import_module
+from django.utils.module_loading import module_has_submodule
+
+import imp
+import sys
+import os
+import threading
+
+
+class MultipleInstancesReturned(Exception):
+    "The function returned multiple App instances with the same label"
+    pass
+
 class App(object):
-    def __init__(self, label):
+    """
-        if '.' in label:
+    An App in Django is a python package that:
-            label = label.split('.')[-1]
+        - is listen in the INSTALLED_APPS setting
-        self.label = label
+        - has a models.py file that with class(es) subclassing ModelBase
+    """
+    def __init__(self, name):
+        self.name = name
+        try:
+            self.label = name.rsplit('.', 1)[1]
+        except IndexError:
+            self.label = name
         # errors raised when trying to import the app
         self.errors = []
         self.models = []
         self.models_module = None
 
     def __repr__(self):
-        return '<App: %s>' % self.label
+        return '<App: %s>' % self.name
+
+class AppCache(object):
+    """
+    A cache that stores installed applications and their models. Used to
+    provide reverse-relations and for app introspection (e.g. admin).
+    """
+    # Use the Borg pattern to share state between all instances. Details at
+    # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531.
+    __shared_state = dict(
+        # List of App instances
+        app_instances = [],
+
+        # Mapping of app_labels to a dictionary of model names to model code.
+        app_models = SortedDict(),
+
+        # -- Everything below here is only used when populating the cache --
+        loaded = False,
+        handled = {},
+        postponed = [],
+        nesting_level = 0,
+        write_lock = threading.RLock(),
+        _get_models_cache = {},
+    )
+
+    def __init__(self):
+        self.__dict__ = self.__shared_state
+
+    def _populate(self):
+        """
+        Fill in all the cache information. This method is threadsafe, in the
+        sense that every caller will see the same state upon return, and if the
+        cache is already initialised, it does no work.
+        """
+        if self.loaded:
+            return
+        self.write_lock.acquire()
+        try:
+            if self.loaded:
+                return
+            for app_name in settings.INSTALLED_APPS:
+                if app_name in self.handled:
+                    continue
+                self.load_app(app_name, True)
+            if not self.nesting_level:
+                for app_name in self.postponed:
+                    self.load_app(app_name)
+                self.loaded = True
+        finally:
+            self.write_lock.release()
+
+    def load_app(self, app_name, can_postpone=False):
+        """
+        Loads the app with the provided fully qualified name, and returns the
+        model module.
+        """
+        self.handled[app_name] = None
+        self.nesting_level += 1
+
+        try:
+            app_module = import_module(app_name)
+        except ImportError:
+            # If the import fails, we assume it was because an path to a
+            # class was passed (e.g. "foo.bar.MyApp")
+            # We split the app_name by the rightmost dot to get the path
+            # and classname, and then try importing it again
+            if not '.' in app_name:
+                raise
+            app_name, app_classname = app_name.rsplit('.', 1)
+            app_module = import_module(app_name)
+            app_class = getattr(app_module, app_classname)
+        else:
+            app_class = App
+
+        # check if an app instance with that name already exists
+        app_instance = self.find_app(app_name)
+        if not app_instance:
+            app_instance = app_class(app_name)
+            self.app_instances.append(app_instance)
+
+        try:
+            models = import_module('.models', app_name)
+        except ImportError:
+            self.nesting_level -= 1
+            # If the app doesn't have a models module, we can just ignore the
+            # ImportError and return no models for it.
+            if not module_has_submodule(app_module, 'models'):
+                return None
+            # But if the app does have a models module, we need to figure out
+            # whether to suppress or propagate the error. If can_postpone is
+            # True then it may be that the package is still being imported by
+            # Python and the models module isn't available yet. So we add the
+            # app to the postponed list and we'll try it again after all the
+            # recursion has finished (in populate). If can_postpone is False
+            # then it's time to raise the ImportError.
+            else:
+                if can_postpone:
+                    self.postponed.append(app_name)
+                    return None
+                else:
+                    raise
+
+        self.nesting_level -= 1
+        app = self.find_app(app_name.split('.')[-1])
+        if app and models is not app.models_module:
+            app.models_module = models
+        return models
+
+    def find_app(self, name):
+        "Returns the App instance that matches name"
+        for app in self.app_instances:
+            if app.name == name:
+                return app
+
+    def create_app(self, name):
+        """create an app instance"""
+        name = name.split('.')[-1]
+        app = self.find_app(name)
+        if not app:
+            app = App(name)
+            self.app_instances.append(app)
+        return app
+
+    def app_cache_ready(self):
+        """
+        Returns true if the model cache is fully populated.
+
+        Useful for code that wants to cache the results of get_models() for
+        themselves once it is safe to do so.
+        """
+        return self.loaded
+
+    def get_apps(self):
+        "Returns a list of all installed modules that contain models."
+        self._populate()
+
+        # Ensure the returned list is always in the same order (with new apps
+        # added at the end). This avoids unstable ordering on the admin app
+        # list page, for example.
+        return [app.models_module for app in self.app_instances\
+                if app.models_module]
+
+    def get_app(self, app_label, emptyOK=False):
+        """
+        Returns the module containing the models for the given app_label. If
+        the app has no models in it and 'emptyOK' is True, returns None.
+        """
+        self._populate()
+        self.write_lock.acquire()
+        try:
+            for app_name in settings.INSTALLED_APPS:
+                if app_label == app_name.split('.')[-1]:
+                    mod = self.load_app(app_name, False)
+                    if mod is None:
+                        if emptyOK:
+                            return None
+                    else:
+                        return mod
+            raise ImproperlyConfigured("App with label %s could not be found" % app_label)
+        finally:
+            self.write_lock.release()
+
+    def get_app_errors(self):
+        "Returns the map of known problems with the INSTALLED_APPS."
+        self._populate()
+        errors = {}
+        for app in self.app_instances:
+            if app.errors:
+                errors.update({app.label: app.errors})
+        return errors
+
+    def get_models(self, app_mod=None, include_auto_created=False, include_deferred=False):
+        """
+        Given a module containing models, returns a list of the models.
+        Otherwise returns a list of all installed models.
+
+        By default, auto-created models (i.e., m2m models without an
+        explicit intermediate table) are not included. However, if you
+        specify include_auto_created=True, they will be.
+
+        By default, models created to satisfy deferred attribute
+        queries are *not* included in the list of models. However, if
+        you specify include_deferred, they will be.
+        """
+        cache_key = (app_mod, include_auto_created, include_deferred)
+        try:
+            return self._get_models_cache[cache_key]
+        except KeyError:
+            pass
+        self._populate()
+        if app_mod:
+            app_label = app_mod.__name__.split('.')[-2]
+            app = self.find_app(app_label)
+            if app:
+                app_list = [app]
+        else:
+            app_list = self.app_instances
+        model_list = []
+        for app in app_list:
+            models = app.models
+            model_list.extend(
+                model for model in models
+                if ((not model._deferred or include_deferred)
+                    and (not model._meta.auto_created or include_auto_created))
+            )
+        self._get_models_cache[cache_key] = model_list
+        return model_list
+
+    def get_model(self, app_label, model_name, seed_cache=True):
+        """
+        Returns the model matching the given app_label and case-insensitive
+        model_name.
+
+        Returns None if no model is found.
+        """
+        if seed_cache:
+            self._populate()
+        app = self.find_app(app_label)
+        if app:
+            for model in app.models:
+                if model_name.lower() == model._meta.object_name.lower():
+                    return model
+
+    def register_models(self, app_label, *models):
+        """
+        Register a set of models as belonging to an app.
+        """
+        # Check if there is an existing app instance
+        # If there are more than one app instance with the
+        # app_label, an MultipleInstancesReturned is raised
+        app_instances = [app for app in self.app_instances\
+                if app.label == app_label]
+        if len(app_instances) > 1:
+            raise MultipleInstancesReturned
+        else:
+            try:
+                app_instance = app_instances[0]
+            except IndexError:
+                app_instance = None
+
+        # Create a new App instance if the ModelBase tries to register
+        # an app that isn't listed in INSTALLED_APPS
+        if not app_instance:
+            app_instance = App(app_label)
+            self.app_instances.append(app_instance)
+
+        for model in models:
+            # Store as 'name: model' pair in a dictionary
+            # in the models list of the App instance
+            model_name = model._meta.object_name.lower()
+            model_dict = self.app_models.setdefault(app_label, SortedDict())
+            if model_name in model_dict:
+                # The same model may be imported via different paths (e.g.
+                # appname.models and project.appname.models). We use the source
+                # filename as a means to detect identity.
+                fname1 = os.path.abspath(sys.modules[model.__module__].__file__)
+                fname2 = os.path.abspath(sys.modules[model_dict[model_name].__module__].__file__)
+                # Since the filename extension could be .py the first time and
+                # .pyc or .pyo the second time, ignore the extension when
+                # comparing.
+                if os.path.splitext(fname1)[0] == os.path.splitext(fname2)[0]:
+                    continue
+            model_dict[model_name] = model
+            app_instance.models.append(model)
+        self._get_models_cache.clear()

django/db/models/loading.py

@@ -15,230 +15,7 @@ import threading
 __all__ = ('get_apps', 'get_app', 'get_models', 'get_model', 'register_models',
         'load_app', 'app_cache_ready')
 
-class AppCache(object):
+from django.core.apps import AppCache
-    """
-    A cache that stores installed applications and their models. Used to
-    provide reverse-relations and for app introspection (e.g. admin).
-    """
-    # Use the Borg pattern to share state between all instances. Details at
-    # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531.
-    __shared_state = dict(
-        # List of App instances
-        app_instances = [],
-
-        # Mapping of app_labels to a dictionary of model names to model code.
-        app_models = SortedDict(),
-
-        # -- Everything below here is only used when populating the cache --
-        loaded = False,
-        handled = {},
-        postponed = [],
-        nesting_level = 0,
-        write_lock = threading.RLock(),
-        _get_models_cache = {},
-    )
-
-    def __init__(self):
-        self.__dict__ = self.__shared_state
-        # Create App instances for the apps in INSTALLED_APPS
-        for app_name in settings.INSTALLED_APPS:
-            self.app_instances.append(App(app_name))
-
-    def _populate(self):
-        """
-        Fill in all the cache information. This method is threadsafe, in the
-        sense that every caller will see the same state upon return, and if the
-        cache is already initialised, it does no work.
-        """
-        if self.loaded:
-            return
-        self.write_lock.acquire()
-        try:
-            if self.loaded:
-                return
-            for app_name in settings.INSTALLED_APPS:
-                if app_name in self.handled:
-                    continue
-                self.load_app(app_name, True)
-            if not self.nesting_level:
-                for app_name in self.postponed:
-                    self.load_app(app_name)
-                self.loaded = True
-        finally:
-            self.write_lock.release()
-
-    def load_app(self, app_name, can_postpone=False):
-        """
-        Loads the app with the provided fully qualified name, and returns the
-        model module.
-        """
-        self.handled[app_name] = None
-        self.nesting_level += 1
-        app_module = import_module(app_name)
-        try:
-            models = import_module('.models', app_name)
-        except ImportError:
-            self.nesting_level -= 1
-            # If the app doesn't have a models module, we can just ignore the
-            # ImportError and return no models for it.
-            if not module_has_submodule(app_module, 'models'):
-                return None
-            # But if the app does have a models module, we need to figure out
-            # whether to suppress or propagate the error. If can_postpone is
-            # True then it may be that the package is still being imported by
-            # Python and the models module isn't available yet. So we add the
-            # app to the postponed list and we'll try it again after all the
-            # recursion has finished (in populate). If can_postpone is False
-            # then it's time to raise the ImportError.
-            else:
-                if can_postpone:
-                    self.postponed.append(app_name)
-                    return None
-                else:
-                    raise
-
-        self.nesting_level -= 1
-        app = self.find_app(app_name.split('.')[-1])
-        if app and models is not app.models_module:
-            app.models_module = models
-        return models
-
-    def find_app(self, app_label):
-        "Returns the App instance that matches app_label"
-        for app in self.app_instances:
-            if app.label == app_label:
-                return app
-
-    def app_cache_ready(self):
-        """
-        Returns true if the model cache is fully populated.
-
-        Useful for code that wants to cache the results of get_models() for
-        themselves once it is safe to do so.
-        """
-        return self.loaded
-
-    def get_apps(self):
-        "Returns a list of all installed modules that contain models."
-        self._populate()
-
-        # Ensure the returned list is always in the same order (with new apps
-        # added at the end). This avoids unstable ordering on the admin app
-        # list page, for example.
-        return [app.models_module for app in self.app_instances\
-                if app.models_module]
-
-    def get_app(self, app_label, emptyOK=False):
-        """
-        Returns the module containing the models for the given app_label. If
-        the app has no models in it and 'emptyOK' is True, returns None.
-        """
-        self._populate()
-        self.write_lock.acquire()
-        try:
-            for app_name in settings.INSTALLED_APPS:
-                if app_label == app_name.split('.')[-1]:
-                    mod = self.load_app(app_name, False)
-                    if mod is None:
-                        if emptyOK:
-                            return None
-                    else:
-                        return mod
-            raise ImproperlyConfigured("App with label %s could not be found" % app_label)
-        finally:
-            self.write_lock.release()
-
-    def get_app_errors(self):
-        "Returns the map of known problems with the INSTALLED_APPS."
-        self._populate()
-        errors = {}
-        for app in self.app_instances:
-            if app.errors:
-                errors.update({app.label: app.errors})
-        return errors
-
-    def get_models(self, app_mod=None, include_auto_created=False, include_deferred=False):
-        """
-        Given a module containing models, returns a list of the models.
-        Otherwise returns a list of all installed models.
-
-        By default, auto-created models (i.e., m2m models without an
-        explicit intermediate table) are not included. However, if you
-        specify include_auto_created=True, they will be.
-
-        By default, models created to satisfy deferred attribute
-        queries are *not* included in the list of models. However, if
-        you specify include_deferred, they will be.
-        """
-        cache_key = (app_mod, include_auto_created, include_deferred)
-        try:
-            return self._get_models_cache[cache_key]
-        except KeyError:
-            pass
-        self._populate()
-        if app_mod:
-            app_label = app_mod.__name__.split('.')[-2]
-            app = self.find_app(app_label)
-            if app:
-                app_list = [app]
-        else:
-            app_list = self.app_instances
-        model_list = []
-        for app in app_list:
-            models = app.models
-            model_list.extend(
-                model for model in models
-                if ((not model._deferred or include_deferred)
-                    and (not model._meta.auto_created or include_auto_created))
-            )
-        self._get_models_cache[cache_key] = model_list
-        return model_list
-
-    def get_model(self, app_label, model_name, seed_cache=True):
-        """
-        Returns the model matching the given app_label and case-insensitive
-        model_name.
-
-        Returns None if no model is found.
-        """
-        if seed_cache:
-            self._populate()
-        app = self.find_app(app_label)
-        if app:
-            for model in app.models:
-                if model_name.lower() == model._meta.object_name.lower():
-                    return model
-
-    def register_models(self, app_label, *models):
-        """
-        Register a set of models as belonging to an app.
-        """
-        # Create a new App instance if an app in INSTALLED_APPS
-        # imports another package that has models
-        app = self.find_app(app_label)
-        if not app:
-            app = App(app_label)
-            self.app_instances.append(app)
-        for model in models:
-            # Store as 'name: model' pair in a dictionary
-            # in the models list of the App instance
-            model_name = model._meta.object_name.lower()
-            model_dict = self.app_models.setdefault(app_label, SortedDict())
-            if model_name in model_dict:
-                # The same model may be imported via different paths (e.g.
-                # appname.models and project.appname.models). We use the source
-                # filename as a means to detect identity.
-                fname1 = os.path.abspath(sys.modules[model.__module__].__file__)
-                fname2 = os.path.abspath(sys.modules[model_dict[model_name].__module__].__file__)
-                # Since the filename extension could be .py the first time and
-                # .pyc or .pyo the second time, ignore the extension when
-                # comparing.
-                if os.path.splitext(fname1)[0] == os.path.splitext(fname2)[0]:
-                    continue
-            model_dict[model_name] = model
-            app.models.append(model)
-        self._get_models_cache.clear()
-
 cache = AppCache()
 
 # These methods were always module level, so are kept that way for backwards

tests/appcachetests/model_app/models.py

@@ -0,0 +1,5 @@
+from django.db import models
+
+class Person(models.Model):
+    first_name = models.CharField(max_length=30)
+    last_name = models.CharField(max_length=30)

tests/appcachetests/nomodel_app/__init__.py

@@ -0,0 +1,6 @@
+from django.core.apps import App
+
+class MyApp(App):
+
+    def __repr__(self):
+        return '<MyApp: %s>' % self.name

tests/appcachetests/runtests.py

@@ -5,6 +5,7 @@ import threading
 from django.conf import settings
 from django.utils.datastructures import SortedDict
 from django.core.exceptions import ImproperlyConfigured
+from django.core.apps import MultipleInstancesReturned
 
 # remove when tests are integrated into the django testsuite
 settings.configure()
@@ -15,6 +16,7 @@ class AppCacheTestCase(unittest.TestCase):
     """
     TestCase that resets the AppCache after each test.
     """
+
     def setUp(self):
         self.old_installed_apps = settings.INSTALLED_APPS
         settings.INSTALLED_APPS = ()
@@ -48,12 +50,15 @@ class AppCacheTestCase(unittest.TestCase):
         cache.nesting_level = 0
         cache.write_lock = threading.RLock()
         cache._get_models_cache = {}
+        
+        cache.app_instances = []
 
 class AppCacheReadyTests(AppCacheTestCase):
     """
     Tests for the app_cache_ready function that indicates if the cache
     is fully populated.
     """
+
     def test_not_initialized(self):
         """Should return False if the AppCache hasn't been initialized"""
         self.assertFalse(cache.app_cache_ready())
@@ -67,6 +72,7 @@ class AppCacheReadyTests(AppCacheTestCase):
 
 class GetAppsTests(AppCacheTestCase):
     """Tests for the get_apps function"""
+
     def test_get_apps(self):
         """Test that the correct models modules are returned"""
         settings.INSTALLED_APPS = ('django.contrib.auth',
@@ -85,6 +91,7 @@ class GetAppsTests(AppCacheTestCase):
 
 class GetAppTests(AppCacheTestCase):
     """Tests for the get_app function"""
+
     def test_get_app(self):
         """Test that the correct module is returned"""
         settings.INSTALLED_APPS = ('django.contrib.auth',)
@@ -123,6 +130,7 @@ class GetAppTests(AppCacheTestCase):
 
 class GetAppErrorsTests(AppCacheTestCase):
     """Tests for the get_app_errors function"""
+
     def test_get_app_errors(self):
         """Test that the function returns an empty dict"""
         self.assertEqual(cache.get_app_errors(), {})
@@ -130,6 +138,7 @@ class GetAppErrorsTests(AppCacheTestCase):
 
 class GetModelsTests(AppCacheTestCase):
     """Tests for the get_models function"""
+
     def test_get_models(self):
         """Test that the correct model classes are returned"""
         settings.INSTALLED_APPS = ('django.contrib.flatpages',) 
@@ -169,6 +178,7 @@ class GetModelsTests(AppCacheTestCase):
 
 class GetModelTests(AppCacheTestCase):
     """Tests for the get_model function"""
+
     def test_get_model(self):
         """Test that the correct model is returned"""
         settings.INSTALLED_APPS = ('django.contrib.flatpages',)
@@ -188,20 +198,98 @@ class GetModelTests(AppCacheTestCase):
         self.assertEqual(rv, None)
         self.assertFalse(cache.app_cache_ready())
 
+class LoadAppTests(AppCacheTestCase):
+    """Tests for the load_app function"""
+
+    def test_with_models(self):
+        """
+        Test that an app instance is created and the models
+        module is returned
+        """
+        rv = cache.load_app('model_app')
+        app = cache.app_instances[0]
+        self.assertEqual(len(cache.app_instances), 1)
+        self.assertEqual(app.name, 'model_app')
+        self.assertEqual(app.models_module.__name__, 'model_app.models')
+        self.assertEqual(rv.__name__, 'model_app.models')
+
+    def test_without_models(self):
+        """
+        Test that an app instance is created when there are no models
+        """
+        rv = cache.load_app('nomodel_app')
+        app = cache.app_instances[0]
+        self.assertEqual(len(cache.app_instances), 1)
+        self.assertEqual(app.name, 'nomodel_app')
+        self.assertEqual(app.models_module, None)
+        self.assertEqual(rv, None)
+
+    def test_load_app_custom(self):
+        """
+        Test that a custom app instance is created if the function
+        gets passed a classname
+        """
+        from nomodel_app import MyApp
+        rv = cache.load_app('nomodel_app.MyApp')
+        app = cache.app_instances[0]
+        self.assertEqual(len(cache.app_instances), 1)
+        self.assertEqual(app.name, 'nomodel_app')
+        self.assertTrue(isinstance(app, MyApp))
+        self.assertEqual(app.models_module, None)
+        self.assertEqual(rv, None)
+
+    def test_load_app_twice(self):
+        """
+        Test that loading an app twice results in only one app instance
+        """
+        rv = cache.load_app('model_app')
+        rv2 = cache.load_app('model_app')
+        self.assertEqual(len(cache.app_instances), 1)
+        self.assertEqual(rv.__name__, 'model_app.models')
+        self.assertEqual(rv2.__name__, 'model_app.models')
+
+    def test_load_app_importerror(self):
+        """
+        Test that an ImportError exception is raised if a package cannot
+        be imported
+        """
+        self.assertRaises(ImportError, cache.load_app, 'garageland')
+
 class RegisterModelsTests(AppCacheTestCase):
     """Tests for the register_models function"""
+
     def test_register_models(self):
-        from django.contrib.flatpages.models import FlatPage, Site
+        """
-        cache.register_models('foo', *(FlatPage, Site,))
+        Test that register_models attaches the models to an existing
-        self.assertFalse(cache.app_cache_ready())
+        app instance
-        rv = cache.get_models()
+        """
-        # we have 4 models since the above import will trigger the
+        # We don't need to call the register_models method. Importing the 
-        # ModelBase.__new__, which will call the register_models function
+        # models.py file will suffice. This is done in the load_app function
-        self.assertEqual(len(rv), 4)
+        # The ModelBase will call the register_models method
-        self.assertEqual(rv[0], Site)
+        cache.load_app('model_app')
-        self.assertEqual(rv[1], FlatPage)
+        app = cache.app_instances[0]
-        self.assertEqual(rv[2], FlatPage)
+        self.assertEqual(len(cache.app_instances), 1)
-        self.assertEqual(rv[3], Site)
+        self.assertEqual(app.models[0].__name__, 'Person')
+
+    def test_new_instance(self):
+        """
+        Test a new app instance is created if one doesn't exist, and the
+        models are attached to it.
+        """
+        from model_app.models import Person
+        app = cache.app_instances[0]
+        self.assertEqual(len(cache.app_instances), 1)
+        self.assertEqual(app.name, 'model_app')
+        self.assertEqual(app.models[0].__name__, 'Person')
+
+    def test_multiple_apps_with_same_label(self):
+        """
+        Test that an exception is raised when the function gets passed an
+        app label but there are multiple app instances with that label
+        """
+        cache.load_app('model_app')
+        self.assertRaises(MultipleInstancesReturned, cache.load_app,
+                'same_label.model_app')
 
 if __name__ == '__main__':
     unittest.main()

tests/appcachetests/same_label/model_app/models.py

@@ -0,0 +1,5 @@
+from django.db import models
+
+class User(models.Model):
+    first_name = models.CharField(max_length=30)
+    last_name = models.CharField(max_length=30)

tests/appcachetests/same_label/nomodel_app/__init__.py

@@ -0,0 +1,6 @@
+from django.core.apps import App
+
+class MyApp(App):
+
+    def __repr__(self):
+        return '<MyApp: %s>' % self.name