feat: Support for grouped changesets of draft modifications (#290)

This introduces `DraftChangeLog` and `DraftChangeLogRecord`, which are mostly
draft equivalents of the `PublishLog` and `PublishLogRecord`. A `DraftChangeLog`
entry is created for every group of changes (e.g. an import or a reset), and
`DraftChangeLogRecord` has a record for every individual publishable entity that
was changed. The motivation for these models:

1. Batch changes into logical groupings, e.g. "discard changes in library" or
"import a course's content into this library".

2. Accurate history reconstruction: We don't currently track reset-to-published
operations anywhere, so we can't completely faithfully reconstruct historical
draft information based purely off of the timestamps of when
`PublishableEntityVersions` are created.

It introduces the `bulk_draft_changes_for` context manager, a convenient API for
associating multiple edits into an atomic changeset with one DraftChangeLog.

It also introduces a new model `DraftSideEffect`. This is to capture the idea
that sometimes a change in one publishable entity will affect another one, even
we don't explicitly create a new version of the affected entity. For now, the
only planned side-effects are that changes in child elements affect their parent
containers. The `DraftSideEffect` model could be used more broadly than this in
the future, although we would need to be extremely thoughtful about it use to
avoid write explosions and user confusion. For more details, see:
#290

In a future commit, we expect to introduce an analogous `PublishSideEffect`
record, tied to `PublishLog`.

Bumps package version from 0.22.0 to 0.23.0

Author: ormsbee

openedx_learning/__init__.py

@@ -2,4 +2,4 @@
 Open edX Learning ("Learning Core").
 """
 
-__version__ = "0.22.0"
+__version__ = "0.23.0"

openedx_learning/apps/authoring/publishing/admin.py

@@ -4,10 +4,19 @@
 from __future__ import annotations
 
 from django.contrib import admin
+from django.db.models import Count
 
 from openedx_learning.lib.admin_utils import ReadOnlyModelAdmin, one_to_one_related_model_html
 
-from .models import LearningPackage, PublishableEntity, Published, PublishLog, PublishLogRecord
+from .models import (
+    DraftChangeLog,
+    DraftChangeLogRecord,
+    LearningPackage,
+    PublishableEntity,
+    PublishLog,
+    PublishLogRecord,
+)
+from .models.publish_log import Published
 
 
 @admin.register(LearningPackage)
@@ -171,3 +180,69 @@ def published_at(self, published_obj):
 
     def message(self, published_obj):
         return published_obj.publish_log_record.publish_log.message
+
+
+class DraftChangeLogRecordTabularInline(admin.TabularInline):
+    """
+    Tabular inline for a single Draft change.
+    """
+    model = DraftChangeLogRecord
+
+    fields = (
+        "entity",
+        "title",
+        "old_version_num",
+        "new_version_num",
+    )
+    readonly_fields = fields
+
+    def get_queryset(self, request):
+        queryset = super().get_queryset(request)
+        return queryset.select_related("entity", "old_version", "new_version") \
+                       .order_by("entity__key")
+
+    def old_version_num(self, draft_change: DraftChangeLogRecord):
+        if draft_change.old_version is None:
+            return "-"
+        return draft_change.old_version.version_num
+
+    def new_version_num(self, draft_change: DraftChangeLogRecord):
+        if draft_change.new_version is None:
+            return "-"
+        return draft_change.new_version.version_num
+
+    def title(self, draft_change: DraftChangeLogRecord):
+        """
+        Get the title to display for the DraftChange
+        """
+        if draft_change.new_version:
+            return draft_change.new_version.title
+        if draft_change.old_version:
+            return draft_change.old_version.title
+        return ""
+
+
+@admin.register(DraftChangeLog)
+class DraftChangeSetAdmin(ReadOnlyModelAdmin):
+    """
+    Read-only admin to view Draft changes (via inline tables)
+    """
+    inlines = [DraftChangeLogRecordTabularInline]
+    fields = (
+        "uuid",
+        "learning_package",
+        "num_changes",
+        "changed_at",
+        "changed_by",
+    )
+    readonly_fields = fields
+    list_display = fields
+    list_filter = ["learning_package"]
+
+    def num_changes(self, draft_change_set):
+        return draft_change_set.num_changes
+
+    def get_queryset(self, request):
+        queryset = super().get_queryset(request)
+        return queryset.select_related("learning_package", "changed_by") \
+                       .annotate(num_changes=Count("records"))