use declarative_base for all ORM models

This rewrites the entire model base as declarative models.
This allows us to more easily customize overlay fields
in tables and is more common.

This effort also brought some DB violations to light which
this commit addresses.

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/models/package_relation.py

@@ -1,15 +1,36 @@
+from sqlalchemy import Column, ForeignKey, Integer
 from sqlalchemy.exc import IntegrityError
-from sqlalchemy.orm import mapper
+from sqlalchemy.orm import backref, relationship
 
-from aurweb.db import make_relationship
-from aurweb.models.package import Package
-from aurweb.models.relation_type import RelationType
-from aurweb.schema import PackageRelations
+import aurweb.db
+import aurweb.models.package
+import aurweb.models.relation_type
+
+from aurweb.models.declarative import Base
 
 
-class PackageRelation:
-    def __init__(self, Package: Package = None,
-                 RelationType: RelationType = None,
+class PackageRelation(Base):
+    __tablename__ = "PackageRelations"
+
+    PackageID = Column(
+        Integer, ForeignKey("Packages.ID", ondelete="CASCADE"),
+        nullable=False)
+    Package = relationship(
+        "Package", backref=backref("package_relations", lazy="dynamic"),
+        foreign_keys=[PackageID])
+
+    RelTypeID = Column(
+        Integer, ForeignKey("RelationTypes.ID", ondelete="CASCADE"),
+        nullable=False)
+    RelationType = relationship(
+        "RelationType", backref=backref("package_relations", lazy="dynamic"),
+        foreign_keys=[RelTypeID])
+
+    __mapper_args__ = {"primary_key": [PackageID, RelTypeID]}
+
+    def __init__(self,
+                 Package: aurweb.models.package.Package = None,
+                 RelationType: aurweb.models.relation_type.RelationType = None,
                  RelName: str = None, RelCondition: str = None,
                  RelArch: str = None):
         self.Package = Package
@@ -35,18 +56,3 @@ class PackageRelation:
 
         self.RelCondition = RelCondition
         self.RelArch = RelArch
-
-
-properties = {
-    "Package": make_relationship(Package, PackageRelations.c.PackageID,
-                                 "package_relations"),
-    "RelationType": make_relationship(RelationType,
-                                      PackageRelations.c.RelTypeID,
-                                      "package_relations")
-}
-
-mapper(PackageRelation, PackageRelations, properties=properties,
-       primary_key=[
-           PackageRelations.c.PackageID,
-           PackageRelations.c.RelTypeID
-       ])