fix(invoice): store full invoice number in a database

This is needed for lookups.

weblate_web/invoices/migrations/0004_invoice_number.py

@@ -0,0 +1,46 @@
+# Generated by Django 5.1.2 on 2024-10-18 10:58
+
+import django.db.models.expressions
+import django.db.models.functions.comparison
+import django.db.models.functions.datetime
+import django.db.models.functions.text
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("invoices", "0003_alter_invoice_kind"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="invoice",
+            name="number",
+            field=models.GeneratedField(
+                db_persist=True,
+                expression=django.db.models.functions.text.Concat(
+                    django.db.models.functions.comparison.Cast(
+                        "kind", models.CharField()
+                    ),
+                    django.db.models.functions.comparison.Cast(
+                        django.db.models.expressions.CombinedExpression(
+                            django.db.models.functions.datetime.Extract(
+                                "issue_date", "year"
+                            ),
+                            "%%",
+                            models.Value(2000),
+                        ),
+                        models.CharField(),
+                    ),
+                    django.db.models.functions.text.LPad(
+                        django.db.models.functions.comparison.Cast(
+                            "sequence", models.CharField()
+                        ),
+                        6,
+                        models.Value("0"),
+                    ),
+                ),
+                output_field=models.CharField(max_length=20),
+            ),
+        ),
+    ]

weblate_web/invoices/models.py

@@ -25,7 +25,7 @@
 from django.conf import settings
 from django.core.validators import MaxValueValidator, MinValueValidator
 from django.db import models
-from django.db.models.functions import Extract
+from django.db.models.functions import Cast, Concat, Extract, LPad
 from django.template.loader import render_to_string
 from django.utils.functional import cached_property
 from django.utils.translation import override
@@ -82,6 +82,15 @@ def display_percents(self) -> str:
 
 class Invoice(models.Model):
     sequence = models.IntegerField(editable=False)
+    number = models.GeneratedField(
+        expression=Concat(
+            Cast("kind", models.CharField()),
+            Cast(Extract("issue_date", "year") % 2000, models.CharField()),
+            LPad(Cast("sequence", models.CharField()), 6, models.Value("0")),
+        ),
+        output_field=models.CharField(max_length=20),
+        db_persist=True,
+    )
     issue_date = models.DateField(default=datetime.date.today)
     due_date = models.DateField(blank=True)
     kind = models.IntegerField(choices=InvoiceKindChoices)
@@ -115,15 +124,15 @@ def __str__(self) -> str:
     def save(
         self,
         *,
-        force_insert=False,
-        force_update=False,
+        force_insert: bool = False,
+        force_update: bool = False,
         using=None,
         update_fields=None,
     ):
+        extra_fields: list[str] = []
         if not self.due_date:
             self.due_date = self.issue_date + datetime.timedelta(days=14)
-            if update_fields is not None:
-                update_fields = ("due_date", *update_fields)
+            extra_fields.append("due_date")
         if not self.sequence:
             try:
                 self.sequence = (
@@ -136,19 +145,17 @@ def save(
                 )
             except IndexError:
                 self.sequence = 1
-            if update_fields is not None:
-                update_fields = ("sequence", *update_fields)
+            extra_fields.append("sequence")
+        if extra_fields and update_fields is not None:
+            update_fields = tuple(set(update_fields).union(extra_fields))
+
         super().save(
             force_insert=force_insert,
             force_update=force_update,
             using=using,
             update_fields=update_fields,
         )
 
-    @property
-    def number(self) -> str:
-        return f"{self.kind}{self.issue_date.year % 2000}{self.sequence:05d}"
-
     def render_amount(self, amount: int | Decimal) -> str:
         if self.currency == CurrencyChoices.EUR:
             return f"€{amount}"