Add get_fixed_purl in AffectedPackage, fix from_dict

from_dict is a factory, should be a classmethod

Signed-off-by: Hritik Vijay <hritikxx8@gmail.com>

Author: Hritik14

vulnerabilities/data_source.py

@@ -66,14 +66,12 @@ def to_dict(self):
             "value": self.value,
         }
 
-    @staticmethod
-    def from_dict(severity: dict):
+    @classmethod
+    def from_dict(cls, severity: dict):
         """
         Return a VulnerabilitySeverity object from dict generated by self.to_dict
         """
-        return VulnerabilitySeverity(
-            system=SCORING_SYSTEMS[severity["system"]], value=severity["value"]
-        )
+        return cls(system=SCORING_SYSTEMS[severity["system"]], value=severity["value"])
 
 
 @dataclasses.dataclass(order=True)
@@ -101,12 +99,12 @@ def to_dict(self):
             "severities": [severity.to_dict() for severity in self.severities],
         }
 
-    @staticmethod
-    def from_dict(ref: dict):
+    @classmethod
+    def from_dict(cls, ref: dict):
         """
         Return a Reference object from dict generated by self.to_dict
         """
-        return Reference(
+        return cls(
             reference_id=ref["reference_id"],
             url=ref["url"],
             severities=[
@@ -130,8 +128,16 @@ def __post_init__(self):
         if self.package.version:
             raise ValueError
 
-    @staticmethod
-    def merge(affected_packages: Iterable):
+    def get_fixed_purl(self):
+        """
+        Return PackageURL corresponding to object's fixed_version
+        """
+        fixed_version = self.fixed_version
+        fixed_purl = self.package._replace(version=str(fixed_version))
+        return fixed_purl
+
+    @classmethod
+    def merge(cls, affected_packages: Iterable):
         """
         Return a tuple with all attributes of AffectedPackage as a set
         for all values in the given iterable of AffectedPackage
@@ -165,8 +171,8 @@ def to_dict(self):
             "fixed_version": str(self.fixed_version) if self.fixed_version else None,
         }
 
-    @staticmethod
-    def from_dict(affected_pkg: dict):
+    @classmethod
+    def from_dict(cls, affected_pkg: dict):
         """
         Return an AffectedPackage object from dict generated by self.to_dict
         """
@@ -177,7 +183,7 @@ def from_dict(affected_pkg: dict):
             # TODO: revisit after https://github.com/nexB/univers/issues/10
             fixed_version = affected_version_range.version_class(fixed_version)
 
-        return AffectedPackage(
+        return cls(
             package=package,
             affected_version_range=affected_version_range,
             fixed_version=fixed_version,