1 files changed, 71 insertions, 0 deletions
diff --git a/django/db/models/loading.py b/django/db/models/loading.py
new file mode 100644
index 0000000000..a9e0348f8e
--- /dev/null
+++ b/django/db/models/loading.py
@@ -0,0 +1,71 @@
+"Utilities for loading models and the modules that contain them."
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+
+__all__ = ('get_apps', 'get_app', 'get_models', 'get_model', 'register_models')
+
+_app_list = None # Cache of installed apps.
+_app_models = {} # Dictionary of models against app label
+                 # Each value is a dictionary of model name: model class
+
+def get_apps():
+    "Returns a list of all installed modules that contain models."
+    global _app_list
+    if _app_list is not None:
+        return _app_list
+    _app_list = []
+    for app_name in settings.INSTALLED_APPS:
+        try:
+            _app_list.append(__import__(app_name, '', '', ['models']).models)
+        except (ImportError, AttributeError), e:
+            pass
+    return _app_list
+
+def get_app(app_label):
+    "Returns the module containing the models for the given app_label."
+    for app_name in settings.INSTALLED_APPS:
+        if app_label == app_name.split('.')[-1]:
+            return __import__(app_name, '', '', ['models']).models
+    raise ImproperlyConfigured, "App with label %s could not be found" % app_label
+
+def get_models(app_mod=None):
+    """
+    Given a module containing models, returns a list of the models. Otherwise
+    returns a list of all installed models.
+    """
+    app_list = get_apps() # Run get_apps() to populate the _app_list cache. Slightly hackish.
+    if app_mod:
+        return _app_models.get(app_mod.__name__.split('.')[-2], {}).values()
+    else:
+        model_list = []
+        for app_mod in app_list:
+            model_list.extend(get_models(app_mod))
+        return model_list
+
+def get_model(app_label, model_name):
+    """
+    Returns the model matching the given app_label and case-insensitive model_name.
+    Returns None if no model is found.
+    """
+    get_apps() # Run get_apps() to populate the _app_list cache. Slightly hackish.
+    try:
+        model_dict = _app_models[app_label]
+    except KeyError:
+        return None
+
+    try:
+        return model_dict[model_name.lower()]
+    except KeyError:
+        return None
+
+def register_models(app_label, *models):
+    """
+    Register a set of models as belonging to an app.
+    """
+    for model in models:
+        # Store as 'name: model' pair in a dictionary
+        # in the _app_models dictionary
+        model_name = model._meta.object_name.lower()
+        model_dict = _app_models.setdefault(app_label, {})
+        model_dict[model_name] = model