[BUG] Deleting a Customer Breaks Associated Sales Orders

Add special protected deleted company
Fixes #2788

InvenTree/company/migrations/0043_company_is_deleted.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2022-03-29 22:46
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('company', '0042_supplierpricebreak_updated'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='company',
+            name='is_deleted',
+            field=models.BooleanField(default=False, help_text='Is this company a deleted placeholder?', verbose_name='is deleted'),
+        ),
+    ]

InvenTree/company/models.py

@@ -9,7 +9,7 @@ import os
 
 from django.utils.translation import ugettext_lazy as _
 from django.core.validators import MinValueValidator
-from django.core.exceptions import ValidationError
+from django.core.exceptions import ValidationError, PermissionDenied
 
 from django.db import models
 from django.db.models import Sum, Q, UniqueConstraint
@@ -147,6 +147,8 @@ class Company(models.Model):
 
     is_manufacturer = models.BooleanField(default=False, verbose_name=_('is manufacturer'), help_text=_('Does this company manufacture parts?'))
 
+    is_deleted = models.BooleanField(default=False, verbose_name=_('is deleted'), help_text=_('Is this company a deleted placeholder?'))
+
     currency = models.CharField(
         max_length=3,
         verbose_name=_('Currency'),
@@ -266,6 +268,18 @@ class Company(models.Model):
 
         return self.purchase_orders.filter(status__in=PurchaseOrderStatus.FAILED)
 
+    def save(self, *args, **kwargs):
+        """Save the instance, unless it is the magic already deleted object"""
+        if self.pk and self.is_deleted:
+            raise PermissionDenied(_('This company is a placeholder and can not be updated'))
+        return super().save(*args, **kwargs)
+
+    def delete(self, *args, **kwargs):
+        """Delete the instance, unless it is the magic already deleted object"""
+        if self.is_deleted:
+            raise PermissionDenied(_('This company is a placeholder and can not be deleted'))
+        return super().delete(*args, **kwargs)
+
 
 class Contact(models.Model):
     """ A Contact represents a person who works at a particular company.