Load a job record that holds unknown fields

A downgrade of Bindery no longer stops at the start.

bindery/jobs.py

@@ -4,7 +4,7 @@ import json
 import sqlite3
 import uuid
 from collections import deque
-from dataclasses import asdict, dataclass, field
+from dataclasses import asdict, dataclass, field, fields
 from datetime import datetime, timedelta
 from enum import StrEnum
 from pathlib import Path
@@ -104,7 +104,9 @@ class Job:
 
     @classmethod
     def from_record(cls, record: str) -> "Job":
-        d = json.loads(record)
+        # A record of a newer Bindery can hold fields that this one does not know.
+        known = {f.name for f in fields(cls)}
+        d = {k: v for k, v in json.loads(record).items() if k in known}
         d["mode"] = DownloadMode(d["mode"])
         d["status"] = QueueStatus(d["status"])
         d["created"] = datetime.fromisoformat(d["created"])

tests/test_jobs.py

@@ -1,5 +1,6 @@
 """The job queue: shared jobs, order, cancelling and the job history."""
 
+import json
 from datetime import datetime, timedelta
 
 from bindery import config
@@ -167,3 +168,10 @@ def test_the_api_form_of_a_job_hides_the_path_of_an_upload():
     job = Job(mode=DownloadMode.IMPORT_FILE, options={"path": "/config/uploads/x.epub", "name": "x.epub"})
     assert job.to_dict()["options"] == {"name": "x.epub"}
     assert Job.from_record(job.to_record()).options == job.options
+
+
+def test_a_record_of_a_newer_bindery_loads_without_its_unknown_fields():
+    job = Job(mode=DownloadMode.NEW, story_id=3)
+    record = json.dumps({**json.loads(job.to_record()), "priority": 5})
+    loaded = Job.from_record(record)
+    assert (loaded.id, loaded.story_id, loaded.mode) == (job.id, 3, DownloadMode.NEW)