Add support for Unix domain in connection urls (#423)

unix domain connection urls come in the following format:
- "postgresql://user:password@/dbname?host=/var/lib/postgresql" or
- "postgresql://user:password@/dbname?unix_sock=/var/lib/postgresql"

Author: dbatten5

databases/core.py

@@ -473,7 +473,11 @@ def password(self) -> typing.Optional[str]:
 
     @property
     def hostname(self) -> typing.Optional[str]:
-        return self.components.hostname
+        return (
+            self.components.hostname
+            or self.options.get("host")
+            or self.options.get("unix_sock")
+        )
 
     @property
     def port(self) -> typing.Optional[int]:

tests/test_database_url.py

@@ -29,6 +29,20 @@ def test_database_url_properties():
     assert u.port == 123
     assert u.database == "mydatabase"
 
+    u = DatabaseURL(
+        "postgresql://username:password@/mydatabase?host=/var/run/postgresql/.s.PGSQL.5432"
+    )
+    assert u.dialect == "postgresql"
+    assert u.username == "username"
+    assert u.password == "password"
+    assert u.hostname == "/var/run/postgresql/.s.PGSQL.5432"
+    assert u.database == "mydatabase"
+
+    u = DatabaseURL(
+        "postgresql://username:password@/mydatabase?unix_sock=/var/run/postgresql/.s.PGSQL.5432"
+    )
+    assert u.hostname == "/var/run/postgresql/.s.PGSQL.5432"
+
 
 def test_database_url_escape():
     u = DatabaseURL(f"postgresql://username:{quote('[password')}@localhost/mydatabase")