1 files changed, 80 insertions, 0 deletions
diff --git a/procurement/migrations/0002_add_representative.py b/procurement/migrations/0002_add_representative.py
new file mode 100644
index 0000000..86a2f38
--- /dev/null
+++ b/procurement/migrations/0002_add_representative.py
@@ -0,0 +1,80 @@
+# Generated by Django 2.1.2 on 2018-10-18 02:18
+
+from django.db import migrations, models
+import django.db.models.deletion
+import warnings
+
+def copy_reps_forward(apps, editor):
+    Supplier = apps.get_model("procurement", "Supplier")
+    Representative = apps.get_model("procurement", "Representative")
+    suppliers = Supplier.objects.all()
+    for sup in suppliers:
+        name = sup.representative_name
+        email = sup.representative_email
+        rep = Representative(name=name, email=email, supplier=sup)
+        rep.save()
+
+class ReverseMigrationDataLossWarning(UserWarning):
+    def __init__(self, supplier, kept_rep, lost_reps):
+        self.supplier = supplier
+        self.kept_rep = kept_rep
+        self.lost_reps = lost_reps
+
+    @staticmethod
+    def format_rep(rep):
+        return '{} <{}>'.format(rep.name, rep.email)
+
+    def __str__(self):
+        return "Supplier {} has multiple representatives, only keeping {}. {} will be lost".format(self.supplier.name, self.format_rep(self.kept_rep), [self.format_rep(rep) for rep in self.lost_reps])
+
+def copy_reps_rev(apps, editor):
+    warnings.filterwarnings("always", category=ReverseMigrationDataLossWarning)
+    Supplier = apps.get_model("procurement", "Supplier")
+    Representative = apps.get_model("procurement", "Representative")
+    suppliers = Supplier.objects.all()
+    for sup in suppliers:
+        reps = sup.representatives.all()
+        if reps:
+            keep = reps[0]
+            if len(reps) > 1:
+                lost = reps[1:]
+                warnings.warn(ReverseMigrationDataLossWarning(sup, keep, lost))
+            sup.representative_name = keep.name
+            sup.representative_email = keep.email
+            sup.save()
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('procurement', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Representative',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('created', models.DateTimeField(auto_now_add=True)),
+                ('updated', models.DateTimeField(auto_now=True)),
+                ('name', models.CharField(max_length=255)),
+                ('email', models.CharField(max_length=255)),
+            ],
+            options={
+                'abstract': False,
+            },
+        ),
+        migrations.AddField(
+            model_name='representative',
+            name='supplier',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='representatives', to='procurement.Supplier'),
+        ),
+        migrations.RunPython(copy_reps_forward, copy_reps_rev),
+        migrations.RemoveField(
+            model_name='supplier',
+            name='representative_email',
+        ),
+        migrations.RemoveField(
+            model_name='supplier',
+            name='representative_name',
+        ),
+    ]