Fix Wagtail article publish regressions

apps/blog/models.py

@@ -222,7 +222,24 @@ class ArticlePageAdminForm(WagtailAdminPageForm):
             self.initial["category"] = default_category.pk
 
     def clean(self):
+        cleaned_data = getattr(self, "cleaned_data", {})
+        self._apply_defaults(cleaned_data)
+        self.cleaned_data = cleaned_data
+
         cleaned_data = super().clean()
+        self._apply_defaults(cleaned_data)
+
+        if not cleaned_data.get("slug"):
+            self.add_error("slug", "Slug is required.")
+        if not cleaned_data.get("author"):
+            self.add_error("author", "Author is required.")
+        if not cleaned_data.get("category"):
+            self.add_error("category", "Category is required.")
+        if not cleaned_data.get("summary"):
+            self.add_error("summary", "Summary is required.")
+        return cleaned_data
+
+    def _apply_defaults(self, cleaned_data: dict[str, Any]) -> dict[str, Any]:
         title = (cleaned_data.get("title") or "").strip()
 
         if not cleaned_data.get("slug") and title:
@@ -237,14 +254,6 @@ class ArticlePageAdminForm(WagtailAdminPageForm):
                 max_chars=self.SUMMARY_MAX_CHARS,
             ) or title
 
-        if not cleaned_data.get("slug"):
-            self.add_error("slug", "Slug is required.")
-        if not cleaned_data.get("author"):
-            self.add_error("author", "Author is required.")
-        if not cleaned_data.get("category"):
-            self.add_error("category", "Category is required.")
-        if not cleaned_data.get("summary"):
-            self.add_error("summary", "Summary is required.")
         return cleaned_data
 
     def _get_default_author(self, *, create: bool) -> Author | None:
@@ -374,9 +383,20 @@ class ArticlePage(SeoMixin, Page):
             self.summary = _generate_summary_from_stream(self.body) or self.title
         if not self.published_date and self.first_published_at:
             self.published_date = self.first_published_at
-        self.read_time_mins = self._compute_read_time()
+        if self._should_refresh_read_time():
+            self.read_time_mins = self._compute_read_time()
         return super().save(*args, **kwargs)
 
+    def _should_refresh_read_time(self) -> bool:
+        if not self.pk:
+            return True
+
+        previous = type(self).objects.only("body").filter(pk=self.pk).first()
+        if previous is None:
+            return True
+
+        return previous.body_text != self.body_text
+
     def _compute_read_time(self) -> int:
         words = []
         for block in self.body: