Add an option for exact_match purl QuerySet lookups #118 (#156)

Signed-off-by: tdruez <tdruez@nexb.com>

CHANGELOG.rst

@@ -7,6 +7,10 @@ Changelog
 - Add support for Composer in ``purl2url`` and ``url2purl``.
   https://github.com/package-url/packageurl-python/pull/144
 
+- Add an option for ``exact_match`` purl QuerySet lookups in the
+  ``PackageURLQuerySetMixin.for_package_url``method.
+  https://github.com/package-url/packageurl-python/issues/118
+
 0.15.0 (2024-03-12)
 -------------------
 

src/packageurl/contrib/django/filters.py

@@ -30,20 +30,24 @@
 class PackageURLFilter(django_filters.CharFilter):
     """
     Filter by an exact Package URL string.
-    The special "EMPTY" value allows to retrieve objects with empty
-    Package URL.
 
-    This filter depends on a `for_package_url` and `empty_package_url`
+    The special "EMPTY" value allows retrieval of objects with an empty Package URL.
+
+    This filter depends on `for_package_url` and `empty_package_url`
     methods to be available on the Model Manager,
     see for example `PackageURLQuerySetMixin`.
+
+    When exact_match_only is True, the filter will match only exact Package URL strings.
     """
 
     is_empty = "EMPTY"
+    exact_match_only = False
     help_text = (
         'Match Package URL. Use "EMPTY" as value to retrieve objects with empty Package URL.'
     )
 
     def __init__(self, *args, **kwargs):
+        self.exact_match_only = kwargs.pop("exact_match_only", False)
         kwargs.setdefault("help_text", self.help_text)
         super().__init__(*args, **kwargs)
 
@@ -58,4 +62,4 @@ def filter(self, qs, value):
         if value == self.is_empty:
             return qs.empty_package_url()
 
-        return qs.for_package_url(value)
+        return qs.for_package_url(value, exact_match=self.exact_match_only)

src/packageurl/contrib/django/models.py

@@ -37,12 +37,18 @@ class PackageURLQuerySetMixin:
     Add Package URL filtering methods to a django.db.models.QuerySet.
     """
 
-    def for_package_url(self, purl_str, encode=True):
+    def for_package_url(self, purl_str, encode=True, exact_match=False):
         """
-        Filter the QuerySet with the provided Package URL string.
-        The purl string is validated and transformed into filtering lookups.
+        Filter the QuerySet based on a Package URL (purl) string with an option for
+        exact match filtering.
+
+        When `exact_match` is False (default), the method will match any purl with the
+        same base fields as `purl_str` and allow variations in other fields.
+        When `exact_match` is True, only the identical purl will be returned.
         """
-        lookups = purl_to_lookups(purl_str=purl_str, encode=encode)
+        lookups = purl_to_lookups(
+            purl_str=purl_str, encode=encode, include_empty_fields=exact_match
+        )
         if lookups:
             return self.filter(**lookups)
         return self.none()

src/packageurl/contrib/django/utils.py

@@ -28,10 +28,14 @@
 from packageurl import PackageURL
 
 
-def purl_to_lookups(purl_str, encode=True):
+def purl_to_lookups(purl_str, encode=True, include_empty_fields=False):
     """
-    Return a lookups dict built from the provided `purl` string.
-    Those lookups can be used as QuerySet filters.
+    Return a lookups dictionary built from the provided `purl` (Package URL) string.
+    These lookups can be used as QuerySet filters.
+    If include_empty_fields is provided, the resulting dictionary will include fields
+    with empty values. This is useful to get exact match.
+    Note that empty values are always returned as empty strings as the model fields
+    are defined with `blank=True` and `null=False`.
     """
     if not purl_str.startswith("pkg:"):
         purl_str = "pkg:" + purl_str
@@ -41,8 +45,11 @@ def purl_to_lookups(purl_str, encode=True):
     except ValueError:
         return  # Not a valid PackageURL
 
-    package_url_dict = package_url.to_dict(encode=encode)
-    return without_empty_values(package_url_dict)
+    package_url_dict = package_url.to_dict(encode=encode, empty="")
+    if include_empty_fields:
+        return package_url_dict
+    else:
+        return without_empty_values(package_url_dict)
 
 
 def without_empty_values(input_dict):

tests/contrib/test_utils.py

@@ -58,6 +58,22 @@ def test_purl_to_lookups_with_encode():
     }
 
 
+def test_purl_to_lookups_include_empty_fields():
+    purl_str = "pkg:alpine/openssl"
+    assert purl_to_lookups(purl_str) == {
+        "type": "alpine",
+        "name": "openssl",
+    }
+    assert purl_to_lookups(purl_str, include_empty_fields=True) == {
+        "type": "alpine",
+        "namespace": "",
+        "name": "openssl",
+        "version": "",
+        "qualifiers": "",
+        "subpath": "",
+    }
+
+
 def test_get_golang_purl():
     assert None == get_golang_purl(None)
     golang_purl_1 = get_golang_purl(