Add guarded stored-value decoding and safe schedule display

.github/workflows/ci.yml

@@ -232,6 +232,79 @@ jobs:
       # the sqlite job.
       - run: timeout -s ABRT 1500 python -m pytest -q
 
+  # The stored-row reader decodes a date and time by one rule on every driver.
+  # psycopg2 and mysqlclient read some of the values it refuses (PostgreSQL's
+  # 'infinity' as the largest datetime, a MySQL zero date as None), so the
+  # reader's tests run on each of them as well as on psycopg 3 and PyMySQL.
+  # Only the reader's file: it is the code the driver changes, and these legs
+  # install the driver the suite's other legs leave out. Django prefers
+  # psycopg 3 when both are installed, so psycopg is not installed here.
+  test-postgres-psycopg2:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    name: postgres psycopg2 (stored-row reader)
+    services:
+      postgres:
+        image: postgres:16
+        env:
+          POSTGRES_PASSWORD: ox
+        ports:
+          - 54329:5432
+        options: >-
+          --health-cmd "pg_isready -U postgres"
+          --health-interval 5s
+          --health-timeout 5s
+          --health-retries 10
+    env:
+      DJANGO_SETTINGS_MODULE: tests.settings_postgres
+      PYTHONFAULTHANDLER: "1"
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97  # v7
+        with:
+          python-version: "3.14"
+      - run: python -m pip install --upgrade pip
+      - run: python -m pip install -e . "Django~=6.1.0" pytest pytest-django psycopg2-binary prometheus-client "celery>=5.6"
+      - run: python -c "from django.db.backends.postgresql import base; assert base.Database.__name__ == 'psycopg2', base.Database"
+      - run: timeout -s ABRT 1500 python -m pytest -q tests/test_stored_read.py
+
+  test-mysql-mysqlclient:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    name: mysql mysqlclient (stored-row reader)
+    services:
+      mysql:
+        image: mysql:8
+        env:
+          MYSQL_ROOT_PASSWORD: ox
+          MYSQL_DATABASE: oxtest
+        ports:
+          - 33069:3306
+        options: >-
+          --health-cmd "mysqladmin ping -h 127.0.0.1 -uroot -pox"
+          --health-interval 5s
+          --health-timeout 5s
+          --health-retries 20
+    env:
+      DJANGO_SETTINGS_MODULE: tests.settings_mysql
+      PYTHONFAULTHANDLER: "1"
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97  # v7
+        with:
+          python-version: "3.14"
+      - run: sudo apt-get update && sudo apt-get install -y libmysqlclient-dev pkg-config
+      - run: python -m pip install --upgrade pip
+      - run: python -m pip install -e . "Django~=6.1.0" pytest pytest-django mysqlclient prometheus-client "celery>=5.6"
+      # tests/settings_mysql.py registers PyMySQL only when mysqlclient is
+      # missing; this leg installs no PyMySQL, so MySQLdb is mysqlclient.
+      - run: python -c "import MySQLdb, sys; assert 'pymysql' not in sys.modules"
+      - run: timeout -s ABRT 1500 python -m pytest -q tests/test_stored_read.py
+
   # A >= install resolves to the newest release and cannot test a floor. This
   # leg pins the floor with == so a regression at the bottom of the supported
   # range fails here.
@@ -494,7 +567,7 @@ jobs:
   ci-ok:
     name: ci-ok
     if: always()
-    needs: [test-sqlite, test-postgres, test-postgres-naive, test-postgres-pooled, test-backport-floor, test-pool-floor, wagtail-smoke, test-mysql, lint, types, docs, packaging, zizmor]
+    needs: [test-sqlite, test-postgres, test-postgres-naive, test-postgres-pooled, test-backport-floor, test-pool-floor, wagtail-smoke, test-mysql, test-postgres-psycopg2, test-mysql-mysqlclient, lint, types, docs, packaging, zizmor]
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:

CONTRIBUTING.md

@@ -25,9 +25,7 @@ docker run -d --name ox-pg -e POSTGRES_PASSWORD=ox -p 54329:5432 postgres:16
 DJANGO_SETTINGS_MODULE=tests.settings_postgres .venv/bin/python -m pytest
 ```
 
-Run both before opening a PR; CI tests every supported Python and Django
-version on SQLite and PostgreSQL, and the oldest and newest corners on
-MySQL 8.
+Run both before opening a PR. CI tests every supported Python and Django version on SQLite and PostgreSQL, and the oldest and newest corners on MySQL 8. Separate psycopg2 and mysqlclient jobs are configured to test only the stored-row reader.
 
 ## Style