work out biography_last_updated from version history

ynr/apps/candidates/views/people.py

@@ -126,12 +126,16 @@ def get_context_data(self, **kwargs):
     def get(self, request, *args, **kwargs):
         person_id = self.kwargs["person_id"]
         try:
-            self.person = Person.objects.prefetch_related(
-                "memberships__ballot",
-                "memberships__ballot__post",
-                "memberships__ballot__election",
-                "tmp_person_identifiers",
-            ).get(pk=person_id)
+            self.person = (
+                Person.objects.with_biography_last_updated()
+                .prefetch_related(
+                    "memberships__ballot",
+                    "memberships__ballot__post",
+                    "memberships__ballot__election",
+                    "tmp_person_identifiers",
+                )
+                .get(pk=person_id)
+            )
         except Person.DoesNotExist:
             try:
                 return self.get_person_redirect(person_id)

ynr/apps/data_exports/csv_fields.py

@@ -20,11 +20,19 @@
 
 from django.core.files.storage import default_storage
 from django.db.models import BooleanField, CharField, Expression
-from django.db.models.expressions import Case, Combinable, F, Value, When
+from django.db.models.expressions import (
+    Case,
+    Combinable,
+    F,
+    RawSQL,
+    Value,
+    When,
+)
 from django.db.models.functions import Concat, Substr
 from django.template.defaultfilters import truncatechars
 from django.urls import reverse
 from django.utils.safestring import SafeString
+from people.managers import BIOGRAPHY_LAST_UPDATED_SQL
 from ynr_refactoring.settings import PersonIdentifierFields
 
 
@@ -321,6 +329,7 @@ def link_formatter(value, url):
     value_group="person",
     label="Favourite Biscuit",
 )
+
 csv_fields["statement_to_voters"] = CSVField(
     type="expr",
     value=F("person__biography"),
@@ -331,7 +340,7 @@ def link_formatter(value, url):
 
 csv_fields["statement_last_updated"] = CSVField(
     type="expr",
-    value=F("person__biography_last_updated"),
+    value=RawSQL(BIOGRAPHY_LAST_UPDATED_SQL, []),
     value_group="person",
     label="Statement last updated",
 )

ynr/apps/people/forms/forms.py

@@ -6,7 +6,6 @@
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.core.validators import URLValidator, validate_email
-from django.utils import timezone
 from django.utils.functional import cached_property
 from django.utils.safestring import mark_safe
 from official_documents.models import BallotSOPN
@@ -316,7 +315,6 @@ class Meta:
             "summary",
             "national_identity",
             "name_search_vector",
-            "biography_last_updated",
             "death_date",
         )
 
@@ -419,14 +417,6 @@ def save(self, commit=True, user=None):
                 user=user,
             )
 
-        initial_biography = self.initial.get("biography", None)
-        biography_updated = (
-            "biography" in self.changed_data
-            and initial_biography != self.cleaned_data["biography"]
-        )
-        if biography_updated:
-            self.instance.biography_last_updated = timezone.now()
-
         return super().save(commit)
 
 

ynr/apps/people/managers.py

@@ -4,6 +4,7 @@
 from candidates.models import PersonRedirect
 from django.core.files import File
 from django.db import connection, models
+from django.db.models.expressions import RawSQL
 from ynr_refactoring.settings import PersonIdentifierFields
 
 
@@ -107,6 +108,34 @@ def editable_value_types(self):
         ON people_person FOR EACH ROW EXECUTE PROCEDURE people_person_search_trigger();
 """
 
+BIOGRAPHY_LAST_UPDATED_SQL = """
+CASE
+WHEN biography = '' THEN NULL
+ELSE (
+    WITH expanded AS (
+        SELECT
+            (elem->>'timestamp')::timestamptz AS ts,
+            elem->'data'->>'biography' AS bio
+        FROM jsonb_array_elements(versions) AS elem
+    ),
+    ordered AS (
+        SELECT
+            ts,
+            bio,
+            LAG(bio) OVER (ORDER BY ts) AS prev_bio
+        FROM expanded
+    )
+    SELECT ts
+    FROM ordered
+    WHERE prev_bio IS DISTINCT FROM bio
+    AND bio IS NOT NULL
+    AND bio <> ''
+    ORDER BY ts DESC
+    LIMIT 1
+)
+END
+"""
+
 
 class PersonQuerySet(models.query.QuerySet):
     def alive_now(self):
@@ -134,3 +163,8 @@ def update_name_search(self):
 
     def update_name_search_trigger(self):
         self._run_sql(NAME_SEARCH_TRIGGER_SQL)
+
+    def with_biography_last_updated(self):
+        return self.annotate(
+            biography_last_updated=RawSQL(BIOGRAPHY_LAST_UPDATED_SQL, [])
+        )

ynr/apps/people/merging.py

@@ -72,7 +72,6 @@ class PersonMerger:
             ("birth_date", "merge_person_attrs"),
             ("death_date", "merge_person_attrs"),
             ("biography", "merge_person_attrs"),
-            ("biography_last_updated", "merge_person_attrs"),
             ("other_names", "merge_name_and_other_names"),
             ("family_name", "merge_person_attrs"),
             ("national_identity", "merge_person_attrs"),

ynr/apps/people/migrations/0048_remove_person_biography_last_updated.py

@@ -0,0 +1,19 @@
+# Generated by Django 5.2.8 on 2025-11-26 13:00
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        (
+            "people",
+            "0047_alter_personimage_options_personimage_created_and_more",
+        ),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name="person",
+            name="biography_last_updated",
+        ),
+    ]

ynr/apps/people/models.py

@@ -274,9 +274,6 @@ class Person(TimeStampedModel, models.Model):
         blank=True,
         help_text="An extended account of a person's life",
     )
-    biography_last_updated = models.DateTimeField(
-        "biography last updated", null=True, blank=True
-    )
     national_identity = models.CharField(
         "national identity",
         max_length=128,

ynr/apps/people/tests/test_person_update.py

@@ -4,7 +4,7 @@
 from django.urls import reverse
 from django.utils import timezone
 from freezegun import freeze_time
-from people.models import EditLimitationStatuses
+from people.models import EditLimitationStatuses, Person
 from people.tests.test_person_view import PersonViewSharedTestsMixin
 from webtest import Text
 
@@ -458,15 +458,17 @@ def test_add_candidacy_does_not_update_biography_timestamp(self):
             form["source"] = "Mumsnet"
             form.submit()
 
-            self.person.refresh_from_db()
+            person = Person.objects.with_biography_last_updated().get(
+                pk=self.person.pk
+            )
 
-            self.assertEqual(len(self.person.versions), 1)
+            self.assertEqual(len(person.versions), 1)
             person_response_one = self.app.get(
-                "/person/{}/".format(self.person.pk), user=self.user
+                "/person/{}/".format(person.pk), user=self.user
             )
 
             biography_update_timestamp = (
-                self.person.biography_last_updated.astimezone()
+                person.biography_last_updated.astimezone()
             )
             # format into a string to compare with the response
             biography_update_timestamp = biography_update_timestamp.strftime(
@@ -485,7 +487,7 @@ def test_add_candidacy_does_not_update_biography_timestamp(self):
             # the biography timestamp has not changed
         with freeze_time(later_timestamp):
             candidacy_update_response = self.app.get(
-                "/person/{}/update".format(self.person.pk), user=self.user
+                "/person/{}/update".format(person.pk), user=self.user
             )
             form = candidacy_update_response.forms["person-details"]
             form["memberships-0-party_identifier_0"].select(
@@ -501,25 +503,27 @@ def test_add_candidacy_does_not_update_biography_timestamp(self):
             form["source"] = "http://example.com"
 
             form.submit()
-            self.person.refresh_from_db()
+            person = Person.objects.with_biography_last_updated().get(
+                pk=self.person.pk
+            )
 
-            candidacy = self.person.memberships.first()
+            candidacy = person.memberships.first()
             self.assertEqual(candidacy.party, self.green_party)
             self.assertEqual(candidacy.party_name, self.green_party.name)
 
             candidacy_update_timestamp = (
-                self.person.biography_last_updated.astimezone()
+                person.biography_last_updated.astimezone()
             )
             candidacy_update_timestamp = candidacy_update_timestamp.strftime(
                 "%-d %B %Y %H:%M"
             )
 
             person_response_one = self.app.get(
-                "/person/{}/".format(self.person.pk), user=self.user
+                "/person/{}/".format(person.pk), user=self.user
             )
 
-            self.assertEqual(len(self.person.versions), 2)
-            self.assertNotEqual(self.person.biography_last_updated, None)
+            self.assertEqual(len(person.versions), 2)
+            self.assertNotEqual(person.biography_last_updated, None)
             # assert that timestamp in the first update and second update are the same
             # because the biography should not have been updated in the second update
             self.assertEqual(