django1/django/db/models/loading.py

117 lines
4.4 KiB
Python

"Utilities for loading models and the modules that contain them."
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
import sys
import os
__all__ = ('get_apps', 'get_app', 'get_models', 'get_model', 'register_models')
_app_list = [] # Cache of installed apps.
# Entry is not placed in app_list cache until entire app is loaded.
_app_models = {} # Dictionary of models against app label
# Each value is a dictionary of model name: model class
# Applabel and Model entry exists in cache when individual model is loaded.
_app_errors = {} # Dictionary of errors that were experienced when loading the INSTALLED_APPS
# Key is the app_name of the model, value is the exception that was raised
# during model loading.
_loaded = False # Has the contents of settings.INSTALLED_APPS been loaded?
# i.e., has get_apps() been called?
def get_apps():
"Returns a list of all installed modules that contain models."
global _app_list
global _loaded
if not _loaded:
_loaded = True
for app_name in settings.INSTALLED_APPS:
try:
load_app(app_name)
except Exception, e:
# Problem importing the app
_app_errors[app_name] = e
return _app_list
def get_app(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."
get_apps() # Run get_apps() to populate the _app_list cache. Slightly hackish.
for app_name in settings.INSTALLED_APPS:
if app_label == app_name.split('.')[-1]:
mod = load_app(app_name)
if mod is None:
if emptyOK:
return None
else:
return mod
raise ImproperlyConfigured, "App with label %s could not be found" % app_label
def load_app(app_name):
"Loads the app with the provided fully qualified name, and returns the model module."
global _app_list
mod = __import__(app_name, {}, {}, ['models'])
if not hasattr(mod, 'models'):
return None
if mod.models not in _app_list:
_app_list.append(mod.models)
return mod.models
def get_app_errors():
"Returns the map of known problems with the INSTALLED_APPS"
global _app_errors
get_apps() # Run get_apps() to populate the _app_list cache. Slightly hackish.
return _app_errors
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, 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:
get_apps()
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, {})
if model_dict.has_key(model_name):
# 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