Add history tracking functionality using django-pghistory; implement views, templates, and middleware for event serialization and context management

moderation/admin.py

@@ -2,6 +2,8 @@ from django.contrib import admin
 from django.contrib.admin import AdminSite
 from django.utils.html import format_html
 from django.urls import reverse
+from django.utils.safestring import mark_safe
+import pghistory
 from .models import EditSubmission, PhotoSubmission
 
 class ModerationAdminSite(AdminSite):
@@ -75,6 +77,33 @@ class PhotoSubmissionAdmin(admin.ModelAdmin):
                 obj.reject(request.user, obj.notes)
         super().save_model(request, obj, form, change)
 
+class HistoryAdmin(admin.ModelAdmin):
+    """Admin interface for viewing model history events"""
+    list_display = ['pgh_label', 'pgh_created_at', 'get_object_link', 'get_context']
+    list_filter = ['pgh_label', 'pgh_created_at']
+    readonly_fields = ['pgh_label', 'pgh_obj_id', 'pgh_data', 'pgh_context', 'pgh_created_at']
+    date_hierarchy = 'pgh_created_at'
+
+    def get_object_link(self, obj):
+        """Display a link to the related object if possible"""
+        if obj.pgh_obj and hasattr(obj.pgh_obj, 'get_absolute_url'):
+            url = obj.pgh_obj.get_absolute_url()
+            return format_html('<a href="{}">{}</a>', url, str(obj.pgh_obj))
+        return str(obj.pgh_obj or '')
+    get_object_link.short_description = 'Object'
+
+    def get_context(self, obj):
+        """Format the context data nicely"""
+        if not obj.pgh_context:
+            return '-'
+        html = ['<table>']
+        for key, value in obj.pgh_context.items():
+            html.append(f'<tr><th>{key}</th><td>{value}</td></tr>')
+        html.append('</table>')
+        return mark_safe(''.join(html))
+    get_context.short_description = 'Context'
+
 # Register with moderation site only
 moderation_site.register(EditSubmission, EditSubmissionAdmin)
 moderation_site.register(PhotoSubmission, PhotoSubmissionAdmin)
+moderation_site.register(pghistory.models.Event, HistoryAdmin)

moderation/models.py

@@ -9,11 +9,13 @@ from django.core.exceptions import ObjectDoesNotExist, FieldDoesNotExist
 from django.contrib.auth.base_user import AbstractBaseUser
 from django.contrib.auth.models import AnonymousUser
 from django.utils.text import slugify
+import pghistory
+from core.models import HistoricalModel
 
 UserType = Union[AbstractBaseUser, AnonymousUser]
 
-
-class EditSubmission(models.Model):
+@pghistory.track()  # Track all changes by default
+class EditSubmission(HistoricalModel):
     STATUS_CHOICES = [
         ("PENDING", "Pending"),
         ("APPROVED", "Approved"),
@@ -196,8 +198,8 @@ class EditSubmission(models.Model):
         self.handled_at = timezone.now()
         self.save()
 
-
-class PhotoSubmission(models.Model):
+@pghistory.track()  # Track all changes by default
+class PhotoSubmission(HistoricalModel):
     STATUS_CHOICES = [
         ("PENDING", "Pending"),
         ("APPROVED", "Approved"),
@@ -287,7 +289,6 @@ class PhotoSubmission(models.Model):
         if user_role in ["MODERATOR", "ADMIN", "SUPERUSER"]:
             self.approve(self.user)
 
-
     def escalate(self, moderator: UserType, notes: str = "") -> None:
         """Escalate the photo submission to admin"""
         self.status = "ESCALATED"