def apply_to(settings, prefix="DJANGO", env=None):
prefix += "__"
if not env:
env = environ.Env()
for key, value in os.environ.items():
if key.startswith(prefix):
path_parts = key.split('__')
if len(path_parts) < 2:
continue
path_parts.pop(0)
# parse value
if hasattr(env, path_parts[0]):
value = getattr(env, path_parts[0])(key)
path_parts.pop(0)
else:
value = env(key)
# starting with global settings, walk down the tree to find the intended target for this value
target = settings
for i, path_part in enumerate(path_parts):
# if it's an int, treat it as an array index
if path_part.isdigit():
path_part = int(path_part)
target_type = type(target)
if target_type == list or target_type == tuple:
if len(target) <= path_part:
target += target_type([{}]) * (path_part - len(target) + 1)
else:
raise ValueError(
"Error parsing %s environment variable: "
"If %s%s is an integer, %s%s must be an array." % (
key, prefix, "__".join(path_parts[:i + 1]), prefix, "__".join(path_parts[:i])))
# otherwise it's a dict key -- make sure target exists
elif path_part not in target:
if type(target) != dict:
raise ValueError(
"Error parsing %s environment variable: %s%s is not a dict." % (
key, prefix, "__".join(path_parts[:i + 1])))
target[path_part] = {}
last_target = target
target = target[path_part]
# assign value
last_target[path_part] = value
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