from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
_prefixes = {}
def swappable_setting(app_label, model):
"""
Returns the setting name to use for the given model (i.e. AUTH_USER_MODEL)
"""
prefix = _prefixes.get(app_label, app_label)
setting = "{prefix}_{model}_MODEL".format(
prefix=prefix.upper(),
model=model.upper()
)
# Ensure this attribute exists to avoid migration issues in Django 1.7
if not hasattr(settings, setting):
setattr(settings, setting, join(app_label, model))
return setting
def is_swapped(app_label, model):
"""
Returns the value of the swapped setting, or False if the model hasn't
been swapped.
"""
default_model = join(app_label, model)
setting = swappable_setting(app_label, model)
value = getattr(settings, setting, default_model)
if value != default_model:
return value
else:
return False
def get_model_name(app_label, model):
"""
Returns [app_label.model] unless the model has been swapped, in which case
returns the swappable setting value.
"""
return is_swapped(app_label, model) or join(app_label, model)
def dependency(app_label, model):
"""
Returns a Django 1.7+ style dependency tuple for inclusion in
migration.dependencies[]
"""
from django.db.migrations import swappable_dependency
return swappable_dependency(get_model_name(app_label, model))
def get_model_names(app_label, models):
"""
Map model names to their swapped equivalents for the given app
"""
return dict(
(model, get_model_name(app_label, model))
for model in models
)
def load_model(app_label, model, orm=None, required=True):
"""
Load the specified model class, or the class it was swapped out for.
If a South orm object is provided, it will be used (but only if the
model hasn't been swapped.)
"""
swapped = is_swapped(app_label, model)
if swapped:
app_label, model = split(swapped)
else:
if orm is not None:
return orm[join(app_label, model)]
try:
try:
# django >= 1.7
from django.apps import apps
cls = apps.get_model(app_label, model)
except ImportError:
# django < 1.7
from django.db.models import get_model
cls = get_model(app_label, model)
except LookupError:
# both get_model versions can raise a LookupError
cls = None
if cls is None and required:
raise ImproperlyConfigured(
"Could not find {name}!".format(name=join(app_label, model))
)
return cls
def set_app_prefix(app_label, prefix):
"""
Set a custom prefix to use for the given app (e.g. WQ)
"""
_prefixes[app_label] = prefix
def join(app_label, model):
return "{app_label}.{model}".format(
app_label=app_label,
model=model,
)
def split(model):
app_label, _, model = model.rpartition(".")
return app_label, model
