mirror of https://github.com/django/django.git
[1.7.x] Fixed #22422 -- Moved information about the application loading process to refs/applications.txt.
Backport of deb561bbe2
from master
This commit is contained in:
parent
ae15356061
commit
bde1bc6672
|
@ -306,3 +306,45 @@ Application registry
|
||||||
Raises :exc:`~exceptions.LookupError` if no such application or model
|
Raises :exc:`~exceptions.LookupError` if no such application or model
|
||||||
exists. Raises :exc:`~exceptions.ValueError` when called with a single
|
exists. Raises :exc:`~exceptions.ValueError` when called with a single
|
||||||
argument that doesn't contain exactly one dot.
|
argument that doesn't contain exactly one dot.
|
||||||
|
|
||||||
|
.. _application-loading-process:
|
||||||
|
|
||||||
|
Application loading process
|
||||||
|
===========================
|
||||||
|
|
||||||
|
Django loads application configurations and models as soon as it starts. Here
|
||||||
|
are some common problems you may encounter:
|
||||||
|
|
||||||
|
* ``RuntimeError: App registry isn't ready yet.`` This happens when importing
|
||||||
|
an application configuration or a models module triggers code that depends
|
||||||
|
on the app registry.
|
||||||
|
|
||||||
|
For example, :func:`~django.utils.translation.ugettext()` uses the app
|
||||||
|
registry to look up translation catalogs in applications. To translate at
|
||||||
|
import time, you need :func:`~django.utils.translation.ugettext_lazy()`
|
||||||
|
instead. (Using :func:`~django.utils.translation.ugettext()` would be a bug,
|
||||||
|
because the translation would happen at import time, rather than at each
|
||||||
|
request depending on the active language.)
|
||||||
|
|
||||||
|
Executing database queries with the ORM at import time in models modules
|
||||||
|
will also trigger this exception. The ORM cannot function properly until all
|
||||||
|
models are available.
|
||||||
|
|
||||||
|
Another common culprit is :func:`django.contrib.auth.get_user_model()`. Use
|
||||||
|
the :setting:`AUTH_USER_MODEL` setting to reference the User model at import
|
||||||
|
time.
|
||||||
|
|
||||||
|
* ``ImportError: cannot import name ...`` This happens if the import sequence
|
||||||
|
ends up in a loop.
|
||||||
|
|
||||||
|
To eliminate such problems, you should minimize dependencies between your
|
||||||
|
models modules and do as little work as possible at import time. To avoid
|
||||||
|
executing code at import time, you can move it into a function and cache its
|
||||||
|
results. The code will be executed when you first need its results. This
|
||||||
|
concept is known as "lazy evaluation".
|
||||||
|
|
||||||
|
* ``django.contrib.admin`` will now automatically perform autodiscovery of
|
||||||
|
``admin`` modules in installed applications. To prevent it, change your
|
||||||
|
:setting:`INSTALLED_APPS` to contain
|
||||||
|
``'django.contrib.admin.apps.SimpleAdminConfig'`` instead of
|
||||||
|
``'django.contrib.admin'``.
|
||||||
|
|
|
@ -877,41 +877,8 @@ Start-up sequence
|
||||||
|
|
||||||
Django 1.7 loads application configurations and models as soon as it starts.
|
Django 1.7 loads application configurations and models as soon as it starts.
|
||||||
While this behavior is more straightforward and is believed to be more robust,
|
While this behavior is more straightforward and is believed to be more robust,
|
||||||
regressions cannot be ruled out. You may encounter the following exceptions:
|
regressions cannot be ruled out. See :ref:`application-loading-process` for
|
||||||
|
solutions to some problems you may encounter.
|
||||||
* ``RuntimeError: App registry isn't ready yet.`` This happens when importing
|
|
||||||
an application configuration or a models module triggers code that depends
|
|
||||||
on the app registry.
|
|
||||||
|
|
||||||
For example, :func:`~django.utils.translation.ugettext()` uses the app
|
|
||||||
registry to look up translation catalogs in applications. To translate at
|
|
||||||
import time, you need :func:`~django.utils.translation.ugettext_lazy()`
|
|
||||||
instead. (Using :func:`~django.utils.translation.ugettext()` would be a bug,
|
|
||||||
because the translation would happen at import time, rather than at each
|
|
||||||
request depending on the active language.)
|
|
||||||
|
|
||||||
Executing database queries with the ORM at import time in models modules
|
|
||||||
will also trigger this exception. The ORM cannot function properly until all
|
|
||||||
models are available.
|
|
||||||
|
|
||||||
Another common culprit is :func:`django.contrib.auth.get_user_model()`. Use
|
|
||||||
the :setting:`AUTH_USER_MODEL` setting to reference the User model at import
|
|
||||||
time.
|
|
||||||
|
|
||||||
* ``ImportError: cannot import name ...`` This happens if the import sequence
|
|
||||||
ends up in a loop.
|
|
||||||
|
|
||||||
To eliminate such problems, you should minimize dependencies between your
|
|
||||||
models modules and do as little work as possible at import time. To avoid
|
|
||||||
executing code at import time, you can move it into a function and cache its
|
|
||||||
results. The code will be executed when you first need its results. This
|
|
||||||
concept is known as "lazy evaluation".
|
|
||||||
|
|
||||||
* ``django.contrib.admin`` will now automatically perform autodiscovery of
|
|
||||||
``admin`` modules in installed applications. To prevent it, change your
|
|
||||||
:setting:`INSTALLED_APPS` to contain
|
|
||||||
``'django.contrib.admin.apps.SimpleAdminConfig'`` instead of
|
|
||||||
``'django.contrib.admin'``.
|
|
||||||
|
|
||||||
Standalone scripts
|
Standalone scripts
|
||||||
^^^^^^^^^^^^^^^^^^
|
^^^^^^^^^^^^^^^^^^
|
||||||
|
|
Loading…
Reference in New Issue