Add Python DB API backend

ixmp/__init__.py

@@ -4,6 +4,7 @@
 
 from ._config import config
 from .backend import BACKENDS, ItemType
+from .backend.dbapi import DatabaseBackend
 from .backend.jdbc import JDBCBackend
 from .core import IAMC_IDX, Platform, Scenario, TimeSeries
 from .model import MODELS
@@ -33,6 +34,7 @@
     __version__ = "999"
 
 # Register Backends provided by ixmp
+BACKENDS["dbapi"] = DatabaseBackend
 BACKENDS["jdbc"] = JDBCBackend
 
 # Register Models provided by ixmp

ixmp/_config.py

@@ -267,6 +267,10 @@ def add_platform(self, name, *args, **kwargs):
                                 "JDBCBackend with driver=hsqldb"
                             )
                 assert len(args) == 0
+            elif cls == "dbapi":
+                from ixmp.backend.dbapi import DatabaseBackend
+
+                info = DatabaseBackend.handle_config(args)
             else:
                 raise ValueError(cls)
 

ixmp/backend/base.py

@@ -766,12 +766,12 @@ def clone(
             The cloned Scenario.
         """
 
-    @abstractmethod
     def has_solution(self, s: Scenario):
-        """Return `True` if Scenario *s* has been solved.
+        """OPTIONAL: Return `True` if Scenario *s* has been solved.
 
         If :obj:`True`, model solution data is available from the Backend.
         """
+        raise NotImplementedError
 
     @abstractmethod
     def list_items(self, s: Scenario, type):