Loading docs/ref/applications.txt +42 −0 Original line number Diff line number Diff line Loading @@ -306,3 +306,45 @@ Application registry Raises :exc:`~exceptions.LookupError` if no such application or model exists. Raises :exc:`~exceptions.ValueError` when called with a single 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'``. docs/releases/1.7.txt +2 −35 Original line number Diff line number Diff line Loading @@ -877,41 +877,8 @@ Start-up sequence 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, regressions cannot be ruled out. You may encounter the following exceptions: * ``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'``. regressions cannot be ruled out. See :ref:`application-loading-process` for solutions to some problems you may encounter. Standalone scripts ^^^^^^^^^^^^^^^^^^ Loading Loading
docs/ref/applications.txt +42 −0 Original line number Diff line number Diff line Loading @@ -306,3 +306,45 @@ Application registry Raises :exc:`~exceptions.LookupError` if no such application or model exists. Raises :exc:`~exceptions.ValueError` when called with a single 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'``.
docs/releases/1.7.txt +2 −35 Original line number Diff line number Diff line Loading @@ -877,41 +877,8 @@ Start-up sequence 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, regressions cannot be ruled out. You may encounter the following exceptions: * ``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'``. regressions cannot be ruled out. See :ref:`application-loading-process` for solutions to some problems you may encounter. Standalone scripts ^^^^^^^^^^^^^^^^^^ Loading
