feat(scrapers.admin): create materialized view and admin page

cl/scrapers/admin.py

@@ -1,4 +1,5 @@
 from django.contrib import admin
+from django.db import models
 
 from cl.scrapers.models import (
     PACERFreeDocumentLog,
@@ -29,3 +30,70 @@ class PACERFreeDocumentRowAdmin(admin.ModelAdmin):
 
 
 admin.site.register(UrlHash)
+
+
+class MVLatestOpinions(models.Model):
+    """
+    Model linked to materialized view for monitoring scrapers
+
+    Must use `REFRESH MATERIALIZED VIEW scrapers_mv_latest_opinion`
+    periodically
+    """
+
+    query = """
+    CREATE MATERIALIZED VIEW
+        scrapers_mv_latest_opinion
+    AS
+    (
+    SELECT
+        court_id,
+        max(so.date_created) as latest_creation_date,
+        (now() - max(so.date_created))::text as time_since
+    FROM
+        (
+            SELECT id, court_id
+            FROM search_docket
+            WHERE court_id IN (
+                SELECT id
+                FROM search_court
+                /*
+                    Only check courts with scrapers in use
+                */
+                WHERE
+                    has_opinion_scraper
+                    AND in_use
+            )
+        ) sd
+    INNER JOIN
+        (SELECT id, docket_id FROM search_opinioncluster) soc ON soc.docket_id = sd.id
+    INNER JOIN
+        search_opinion so ON so.cluster_id = soc.id
+    GROUP BY
+        sd.court_id
+    HAVING
+        /*
+            Only return results for courts with no updates in a week
+        */
+        now() - max(so.date_created) > interval '7 days'
+    ORDER BY
+        2 DESC
+    )
+    """
+    # a django model must have a primary key
+    court_id = models.TextField(primary_key=True)
+    latest_creation_date = models.DateField()
+    time_since = models.TextField()
+
+    class Meta:
+        managed = False  # ignore this model in migrations
+        db_table = "scrapers_mv_latest_opinion"
+
+
+@admin.register(MVLatestOpinions)
+class MVLatestOpinionsAdmin(admin.ModelAdmin):
+    """Admin page to look at the latest opinion for each court
+
+    Use this to monitor silently failing scrapers
+    """
+
+    list_display = ["court_id", "latest_creation_date", "time_since"]