Pass ProjectVersionInfo as JSON-safe data

In order to safely pass the data across the celery task `defer` call,
which implicitly JSON de/serializes data, the objects need to be
converted to and from a JSON-compatible shape.

As a simple paradigm for handling this, `serialize_many` and `parse_many`
are added to `ProjectVersionInfo` as classmethods for converting to and
from a list of dicts.
By structuring `ProjectVersionInfo` as a decorator, it's possible to
keep the code within the task definition the same as it was before.

Author: sirosen

readthedocs/builds/tasks.py

@@ -276,8 +276,10 @@ def delete_closed_external_versions(limit=200, days=30 * 3):
 
 
 @app.task(max_retries=1, default_retry_delay=60, queue="web")
+@ProjectVersionInfo.parse_many("tags_data", "branches_data")
 def sync_versions_task(
     project_pk: int,
+    *,
     tags_data: list[ProjectVersionInfo],
     branches_data: list[ProjectVersionInfo],
     **kwargs: object,

readthedocs/projects/datatypes.py

@@ -4,7 +4,19 @@
 classes.
 """
 
+from __future__ import annotations
+
 import dataclasses
+import functools
+import sys
+import typing
+
+
+if typing.TYPE_CHECKING:
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
 
 
 @dataclasses.dataclass
@@ -21,3 +33,36 @@ class ProjectVersionInfo:
 
     verbose_name: str
     identifier: str
+
+    @classmethod
+    def serialize_many(cls, data: typing.Sequence[Self]) -> list[dict[str, str]]:
+        r"""
+        A preparatory step which converts a sequence of ``ProjectVersionInfo``\s into a
+        format suitable for JSON serialization.
+        """
+        return [dataclasses.asdict(item) for item in data]
+
+    @classmethod
+    def parse_many(cls, *argument_names: str) -> typing.Callable[..., typing.Any]:
+        """
+        A decorator which adds a parsing step to deserialize JSON-ified data.
+
+        The keyword argument names which will be targetted for parsing must be supplied
+        as strings to ``parse_many()``.
+        """
+
+        def decorator(func: typing.Callable[..., typing.Any]) -> typing.Callable[..., typing.Any]:
+            @functools.wraps(func)
+            def wrapper(*args: typing.Any, **kwargs: typing.Any) -> typing.Any:
+                for name in argument_names:
+                    if name not in kwargs:
+                        raise TypeError(f"Missing required argument: {name}")
+                    kwargs[name] = [
+                        item if isinstance(item, ProjectVersionInfo) else cls(**item)
+                        for item in kwargs[name]
+                    ]
+                return func(*args, **kwargs)
+
+            return wrapper
+
+        return decorator

readthedocs/projects/tasks/mixins.py

@@ -82,8 +82,8 @@ def sync_versions(self, vcs_repository):
 
         build_tasks.sync_versions_task.delay(
             project_pk=self.data.project.pk,
-            tags_data=tags_data,
-            branches_data=branches_data,
+            tags_data=ProjectVersionInfo.serialize_many(tags_data),
+            branches_data=ProjectVersionInfo.serialize_many(branches_data),
         )
 
     def validate_duplicate_reserved_versions(