add support for title sort to ignore initial article

bookwyrm/migrations/0179_populate_sort_title.py

@@ -0,0 +1,41 @@
+import re
+from itertools import chain
+
+from django.db import migrations, transaction
+from django.db.models import Q
+
+from bookwyrm.settings import LANGUAGE_ARTICLES
+
+
+@transaction.atomic
+def populate_sort_title(apps, schema_editor):
+    Edition = apps.get_model("bookwyrm", "Edition")
+    db_alias = schema_editor.connection.alias
+    editions_wo_sort_title = Edition.objects.using(db_alias).filter(
+        Q(sort_title__isnull=True) | Q(sort_title__exact="")
+    )
+    for edition in editions_wo_sort_title:
+        articles = chain(
+            *(LANGUAGE_ARTICLES.get(language, ()) for language in edition.languages)
+        )
+        if articles:
+            icase_articles = (
+                f"[{a[0].capitalize()}{a[0].lower()}]{a[1:]}" for a in articles
+            )
+            edition.sort_title = re.sub(
+                f'^{" |^".join(icase_articles)} ', "", edition.title
+            )
+        else:
+            edition.sort_title = edition.title
+        edition.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookwyrm", "0178_auto_20230328_2132"),
+    ]
+
+    operations = [
+        migrations.RunPython(populate_sort_title),
+    ]