Merge pull request #442 from blakegong/features/add-dotted-arguments-for-lazy-import

Improve lazy_import() to accept dotted_attributes
This commit is contained in:
Syrus Akbary 2017-03-25 12:15:46 -07:00 committed by GitHub
commit d594a0eca8
2 changed files with 51 additions and 5 deletions

View File

@ -2,10 +2,13 @@ from functools import partial
from importlib import import_module
def import_string(dotted_path):
def import_string(dotted_path, dotted_attributes=None):
"""
Import a dotted module path and return the attribute/class designated by the
last name in the path. Raise ImportError if the import failed.
last name in the path. When a dotted attribute path is also provided, the
dotted attribute path would be applied to the attribute/class retrieved from
the first step, and return the corresponding value designated by the
attribute path. Raise ImportError if the import failed.
"""
try:
module_path, class_name = dotted_path.rsplit('.', 1)
@ -15,12 +18,27 @@ def import_string(dotted_path):
module = import_module(module_path)
try:
return getattr(module, class_name)
result = getattr(module, class_name)
except AttributeError:
raise ImportError('Module "%s" does not define a "%s" attribute/class' % (
module_path, class_name)
)
if not dotted_attributes:
return result
else:
attributes = dotted_attributes.split('.')
traveled_attributes = []
try:
for attribute in attributes:
traveled_attributes.append(attribute)
result = getattr(result, attribute)
return result
except AttributeError:
raise ImportError('Module "%s" does not define a "%s" attribute inside attribute/class "%s"' % (
module_path, '.'.join(traveled_attributes), class_name
))
def lazy_import(dotted_path):
return partial(import_string, dotted_path)
def lazy_import(dotted_path, dotted_attributes=None):
return partial(import_string, dotted_path, dotted_attributes)

View File

@ -1,6 +1,7 @@
from pytest import raises
from graphene import String
from graphene.types.objecttype import ObjectTypeMeta
from ..module_loading import lazy_import, import_string
@ -8,6 +9,9 @@ def test_import_string():
MyString = import_string('graphene.String')
assert MyString == String
MyObjectTypeMeta = import_string('graphene.ObjectType', '__class__')
assert MyObjectTypeMeta == ObjectTypeMeta
def test_import_string_module():
with raises(Exception) as exc_info:
@ -23,7 +27,31 @@ def test_import_string_class():
assert str(exc_info.value) == 'Module "graphene" does not define a "Stringa" attribute/class'
def test_import_string_attributes():
with raises(Exception) as exc_info:
import_string('graphene.String', 'length')
assert str(exc_info.value) == 'Module "graphene" does not define a "length" attribute inside attribute/class ' \
'"String"'
with raises(Exception) as exc_info:
import_string('graphene.ObjectType', '__class__.length')
assert str(exc_info.value) == 'Module "graphene" does not define a "__class__.length" attribute inside ' \
'attribute/class "ObjectType"'
with raises(Exception) as exc_info:
import_string('graphene.ObjectType', '__classa__.__base__')
assert str(exc_info.value) == 'Module "graphene" does not define a "__classa__" attribute inside attribute/class ' \
'"ObjectType"'
def test_lazy_import():
f = lazy_import('graphene.String')
MyString = f()
assert MyString == String
f = lazy_import('graphene.ObjectType', '__class__')
MyObjectTypeMeta = f()
assert MyObjectTypeMeta == ObjectTypeMeta