feat: Derive FK to related stanzas from the stanza variant line code

This commit modifies the `StanzaVariant` model's `save` method to trim the letter code from the `stanza_variation_line_code_starts` field. This allows for easier lookup of the foreign key to the `Stanza` model. Additionally, the commit updates the `__str__` method of the `StanzaVariant` model to display the association between the stanza variation and the stanza it belongs to.

manuscript/migrations/0073_alter_stanzavariant_stanza.py

@@ -0,0 +1,26 @@
+# Generated by Django 5.0.2 on 2024-06-05 16:23
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        (
+            "manuscript",
+            "0072_alter_detail_distance_lines_alter_detail_is_sea_red_and_more",
+        ),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="stanzavariant",
+            name="stanza",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to="manuscript.stanza",
+            ),
+        ),
+    ]

manuscript/migrations/0074_alter_stanzavariant_stanza.py

@@ -0,0 +1,24 @@
+# Generated by Django 5.0.2 on 2024-06-05 16:32
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("manuscript", "0073_alter_stanzavariant_stanza"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="stanzavariant",
+            name="stanza",
+            field=models.ForeignKey(
+                blank=True,
+                editable=False,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to="manuscript.stanza",
+            ),
+        ),
+    ]

manuscript/models.py

@@ -3,11 +3,8 @@
 
 from bs4 import BeautifulSoup
 from django.conf import settings
-from django.core.exceptions import ValidationError
+from django.core.exceptions import ObjectDoesNotExist, ValidationError
 from django.db import models
-from django.db.models import IntegerField
-from django.db.models.functions import Cast
-from django_prose_editor.fields import ProseEditorField
 from prose.fields import RichTextField
 
 logger = logging.getLogger(__name__)
@@ -228,15 +225,6 @@ def __str__(self) -> str:
 class StanzaVariant(models.Model):
     """Notes about variants in a stanza"""
 
-    LINE_VARIANTS = (
-        ("lf", "Lines Flipped"),
-        ("dw", "Different Words"),
-        ("do", "Different Order"),
-        ("dp", "Different Punctuation"),
-        ("ds", "Different Spelling"),
-        ("dc", "Different Capitalization"),
-    )
-
     # TODO: Ability to have variation in lines
     id = models.AutoField(primary_key=True)
     stanza_variation = models.TextField(
@@ -256,17 +244,43 @@ class StanzaVariant(models.Model):
     )
 
     stanza = models.ForeignKey(
-        "Stanza", on_delete=models.PROTECT, blank=True, null=True
+        "Stanza",
+        on_delete=models.CASCADE,
+        blank=True,
+        null=True,
+        editable=False,
     )
 
     def provide_snippet_of_stanza(self):
-        return self.stanza.stanza_text[:100]
+        return self.stanza.stanza_variation[:100]
+
+    def save(self, *args, **kwargs):
+        # we trim the letter code off the stanza_variation_line_code_starts
+        # so we can look for the FK to the Stanza
+        try:
+            stanza_line_code_starts = self.stanza_variation_line_code_starts[:-1]
+        except TypeError:
+            stanza_line_code_starts = None
+
+        try:
+            self.stanza = Stanza.objects.get(
+                stanza_line_code_starts=stanza_line_code_starts
+            )
+        except ObjectDoesNotExist:
+            pass
 
-    def __str__(self) -> str:
-        soup = BeautifulSoup(self.stanza_variation, "html.parser")
-        text = soup.get_text()
+        super().save(*args, **kwargs)
 
-        return text[:100] + "..."
+    def __str__(self) -> str:
+        return (
+            "Stanza "
+            + self.stanza_variation_line_code_starts
+            + " associated with "
+            + self.stanza.stanza_line_code_starts
+            + " ("
+            + self.stanza.related_manuscript.siglum
+            + ")"
+        )
 
 
 class Stanza(models.Model):