Fix author_trigger() recalculating search_vector of the wrong books

bookwyrm/migrations/0196_fix_author_trigger.py

@@ -0,0 +1,52 @@
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookwyrm", "0195_alter_user_preferred_language"),
+    ]
+
+    operations = [
+        # join on bookwyrm_book_authors.author_id instead of .id
+        migrations.RunSQL(
+            sql="""
+                CREATE OR REPLACE FUNCTION author_trigger() RETURNS trigger AS $$
+                begin
+                    WITH book AS (
+                        SELECT bookwyrm_book.id as row_id
+                        FROM bookwyrm_author
+                        LEFT OUTER JOIN bookwyrm_book_authors
+                        ON bookwyrm_book_authors.author_id = new.id
+                        LEFT OUTER JOIN bookwyrm_book
+                        ON bookwyrm_book.id = bookwyrm_book_authors.book_id
+                    )
+                    UPDATE bookwyrm_book SET search_vector = ''
+                    FROM book
+                    WHERE id = book.row_id;
+                    return new;
+                end
+                $$ LANGUAGE plpgsql;
+
+                UPDATE bookwyrm_book SET search_vector = NULL;
+            """,
+            reverse_sql="""
+                CREATE OR REPLACE FUNCTION author_trigger() RETURNS trigger AS $$
+                begin
+                    WITH book AS (
+                        SELECT bookwyrm_book.id as row_id
+                        FROM bookwyrm_author
+                        LEFT OUTER JOIN bookwyrm_book_authors
+                        ON bookwyrm_book_authors.id = new.id
+                        LEFT OUTER JOIN bookwyrm_book
+                        ON bookwyrm_book.id = bookwyrm_book_authors.book_id
+                    )
+                    UPDATE bookwyrm_book SET search_vector = ''
+                    FROM book
+                    WHERE id = book.row_id;
+                    return new;
+                end
+                $$ LANGUAGE plpgsql;
+            """,
+        ),
+    ]