Migrate away from pkg_resources (#1935)

* Migrate away from pkg_resources

Using pkg_resources as an API is deprecated.
Migrate functionality to their importlib and packaging equivalents.

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>

* Add packaging to requirements

Required for packaging.version after the removal of pkg_resources.

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>

---------

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>

haystack/__init__.py

@@ -1,20 +1,21 @@
+from importlib.metadata import PackageNotFoundError, version
+
 import django
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
-from pkg_resources import DistributionNotFound, get_distribution, parse_version
+from packaging.version import Version
 
 from haystack.constants import DEFAULT_ALIAS
 from haystack.utils import loading
 
 __author__ = "Daniel Lindsley"
 
 try:
-    pkg_distribution = get_distribution("django-haystack")
-    __version__ = pkg_distribution.version
-    version_info = pkg_distribution.parsed_version
-except DistributionNotFound:
+    __version__ = version("django-haystack")
+    version_info = Version(__version__)
+except PackageNotFoundError:
     __version__ = "0.0.dev0"
-    version_info = parse_version(__version__)
+    version_info = Version(__version__)
 
 
 if django.VERSION < (3, 2):

setup.py

@@ -3,6 +3,7 @@
 
 install_requires = [
     "Django>=3.2",
+    "packaging",
     "setuptools",
 ]
 

test_haystack/solr_tests/test_solr_backend.py

@@ -10,7 +10,7 @@
 from django.conf import settings
 from django.test import TestCase
 from django.test.utils import override_settings
-from pkg_resources import parse_version
+from packaging.version import Version
 
 from haystack import connections, indexes, reset_search_queries
 from haystack.exceptions import SkipDocument
@@ -1650,7 +1650,7 @@ def test_boost(self):
 
 
 @unittest.skipIf(
-    parse_version(pysolr.__version__) < parse_version("3.1.1"),
+    Version(pysolr.__version__) < Version("3.1.1"),
     "content extraction requires pysolr > 3.1.1",
 )
 class LiveSolrContentExtractionTestCase(TestCase):