feat(omr search): create non-existent folios when indexing manuscript…

… mei

When chants end on a folio where no other chants begin, the folio
does not exist in CantusDB but does have an MEI file. For example, see
folio A14r in Salzinnes. Here, we modify the index_manuscript_mei
command to create a folio in such cases (we check that it's a "real"
folio by making sure the mei file follows a naming convention and then
create the folio if it doesn't exist). The user is alerted to this, and
they must manually add the image_uri to the folio (either through the admin
panel or the map folios process) and then reindex the mei. This is detailed
in issue #891. This is convoluted, but given that we're going to change the
structure of the CU database soon so that it is more closely coupled with
CantusDB, we'll figure out a more permanent solution then -- solving #891).

app/public/cantusdata/management/commands/index_manuscript_mei.py

@@ -1,21 +1,30 @@
 from typing import Any, Dict
 from os import path, listdir
+import re
 
 from django.core.management.base import BaseCommand, CommandParser
 from django.conf import settings
+from solr.core import SolrConnection  # type: ignore
+
 from cantusdata.helpers.mei_processing.mei_tokenizer import MEITokenizer
 from cantusdata.models.folio import Folio
 
-from solr.core import SolrConnection  # type: ignore
 
 MEI4_DIR = path.join("/code", "production-mei-files")
+FOLIO_NUMBER_REGEX = re.compile(r"[a-zA-Z]?\d+[a-z]?")
 
 
 class Command(BaseCommand):
     help = (
         "This command indexes the contents of MEI files in Solr, using"
         "the MEITokenizer class to extract n-grams from the MEI files."
-        "Files must be named in the format [some string]_[folio number].mei."
+        "Files must be named in the format [some string]_[folio number].mei,"
+        "where [folio number] is an optional single letter followed by "
+        "some number of digits followed by an optional"
+        "lowercase single letter. The command currently has a workaround for folios "
+        "that have MEI files but are NOT in CantusDB. See #891 for details "
+        "about how to handle this case -- the command will alert the user "
+        "when it encounters this case."
     )
 
     def add_arguments(self, parser: CommandParser) -> None:
@@ -74,18 +83,27 @@ def handle(self, *args: Any, **options: Any) -> None:
             raise ValueError(f"No folios found for manuscript {manuscript_id}.")
         manuscript_mei_path = path.join(options["mei_dir"], str(manuscript_id))
         if not path.exists(manuscript_mei_path):
-            raise FileNotFoundError(f"--mei-dir path does not exist.")
+            raise FileNotFoundError("--mei-dir path does not exist.")
         manuscript_mei_files = [
             f for f in listdir(manuscript_mei_path) if f.endswith(".mei")
         ]
         if len(manuscript_mei_files) == 0:
             raise FileNotFoundError(f"No MEI files found in {manuscript_mei_path}.")
         for mei_file in manuscript_mei_files:
             folio_number: str = mei_file.split("_")[-1].split(".")[0]
-            if not folio_number in folio_map:
+            if not FOLIO_NUMBER_REGEX.match(folio_number):
                 raise ValueError(
-                    f"Folio number {folio_number} in MEI file {mei_file} does not exist in the database."
+                    f"MEI file {mei_file} does not match the expected format."
+                )
+            if not folio_number in folio_map:
+                self.stdout.write(
+                    self.style.WARNING(
+                        f"Folio number {folio_number} in MEI file "
+                        f"{mei_file} did not exist in the database. Creating record. "
+                        "See #891 for details on how to handle this case."
+                    )
                 )
+                Folio.objects.create(manuscript_id=manuscript_id, number=folio_number)
             tokenizer = MEITokenizer(
                 path.join(manuscript_mei_path, mei_file),
                 min_ngram=options["min_ngram"],
@@ -98,6 +116,7 @@ def handle(self, *args: Any, **options: Any) -> None:
                 doc["image_uri"] = folio_map.get(folio_number, "")
             solr_conn.add_many(ngram_docs)
             solr_conn.commit()
+        return None
 
     def flush_manuscript_ngrams_from_index(
         self, solr_conn: SolrConnection, manuscript_id: int