X-Git-Url: https://plomlompom.com/repos/berlin_corona.txt?a=blobdiff_plain;f=plomtask%2Fversioned_attributes.py;h=ab39df098059e416c7627b5fcefecae2668d7c06;hb=HEAD;hp=d3c364942e3d76edf0eb9618df8366866c603709;hpb=1a9178b2b7bb66e77f3df01a0c7b2812839637ba;p=plomtask

diff --git a/plomtask/versioned_attributes.py b/plomtask/versioned_attributes.py
index d3c3649..8861c98 100644
--- a/plomtask/versioned_attributes.py
+++ b/plomtask/versioned_attributes.py
@@ -4,7 +4,8 @@ from typing import Any
 from sqlite3 import Row
 from time import sleep
 from plomtask.db import DatabaseConnection
-from plomtask.exceptions import HandledException, BadFormatException
+from plomtask.exceptions import (HandledException, BadFormatException,
+                                 NotFoundException)
 
 TIMESTAMP_FMT = '%Y-%m-%d %H:%M:%S.%f'
 
@@ -19,6 +20,12 @@ class VersionedAttribute:
         self.default = default
         self.history: dict[str, str | float] = {}
 
+    def __hash__(self) -> int:
+        history_tuples = tuple((k, v) for k, v in self.history.items())
+        hashable = (self.parent.id_, self.table_name, self.default,
+                    history_tuples)
+        return hash(hashable)
+
     @property
     def _newest_timestamp(self) -> str:
         """Return most recent timestamp."""
@@ -92,6 +99,8 @@ class VersionedAttribute:
 
     def save(self, db_conn: DatabaseConnection) -> None:
         """Save as self.history entries, but first wipe old ones."""
+        if self.parent.id_ is None:
+            raise NotFoundException('cannot save attribute to parent if no ID')
         db_conn.rewrite_relations(self.table_name, 'parent', self.parent.id_,
                                   [[item[0], item[1]]
                                    for item in self.history.items()])