refactor: migrate to question sets for person qs

This means we're starting to use the same system for person questions
as for relationship questions

people/migrations/0022_refactor_person_questions.py

@@ -0,0 +1,55 @@
+# Generated by Django 2.2.10 on 2020-11-23 14:29
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('people', '0021_refactor_person_disciplines'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PersonQuestion',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('version', models.PositiveSmallIntegerField(default=1)),
+                ('text', models.CharField(max_length=255)),
+                ('order', models.SmallIntegerField(default=0)),
+            ],
+            options={
+                'ordering': ['order', 'text'],
+            },
+        ),
+        migrations.CreateModel(
+            name='PersonQuestionChoice',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('text', models.CharField(max_length=255)),
+                ('order', models.SmallIntegerField(default=0)),
+                ('question', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='answers', to='people.PersonQuestion')),
+            ],
+            options={
+                'ordering': ['question__order', 'order', 'text'],
+            },
+        ),
+        migrations.CreateModel(
+            name='PersonAnswerSet',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('timestamp', models.DateTimeField(auto_now_add=True)),
+                ('replaced_timestamp', models.DateTimeField(blank=True, editable=False, null=True)),
+                ('person', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='answer_sets', to='people.Person')),
+                ('question_answers', models.ManyToManyField(to='people.PersonQuestionChoice')),
+            ],
+            options={
+                'ordering': ['timestamp'],
+            },
+        ),
+        migrations.AddConstraint(
+            model_name='personquestionchoice',
+            constraint=models.UniqueConstraint(fields=('question', 'text'), name='unique_question_answer'),
+        ),
+    ]

people/migrations/0023_remove_person_role.py

@@ -0,0 +1,65 @@
+# Generated by Django 2.2.10 on 2020-11-25 15:50
+
+from django.core.exceptions import ObjectDoesNotExist
+from django.db import migrations
+from django.utils import timezone
+
+from .utils.question_sets import port_question
+
+
+def migrate_forward(apps, schema_editor):
+    Person = apps.get_model('people', 'Person')
+    Role = apps.get_model('people', 'Role')
+
+    role_question = port_question(apps, 'Role',
+                                  Role.objects.values_list('name', flat=True))
+
+    for person in Person.objects.all():
+        try:
+            prev_set = person.answer_sets.latest('timestamp')
+
+        except ObjectDoesNotExist:
+            prev_set = None
+
+        try:
+
+            answer_set = person.answer_sets.create()
+            answer_set.question_answers.add(
+                role_question.answers.get(text=person.role.name))
+
+            prev_set.replaced_timestamp = timezone.datetime.now()
+
+        except AttributeError:
+            pass
+
+
+def migrate_backward(apps, schema_editor):
+    Person = apps.get_model('people', 'Person')
+    Role = apps.get_model('people', 'Role')
+
+    for person in Person.objects.all():
+        try:
+            current_answers = person.answer_sets.latest('timestamp')
+            role_answer = current_answers.question_answers.get(
+                question__text='Role')
+            person.role, _ = Role.objects.get_or_create(name=role_answer.text)
+            person.save()
+
+        except ObjectDoesNotExist:
+            pass
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('people', '0022_refactor_person_questions'),
+    ]
+
+    operations = [
+        migrations.RunPython(migrate_forward, migrate_backward),
+        migrations.RemoveField(
+            model_name='person',
+            name='role',
+        ),
+        migrations.DeleteModel('Role'),
+    ]

people/migrations/utils/question_sets.py

@@ -0,0 +1,23 @@
+
+import typing
+
+from django.core.exceptions import ObjectDoesNotExist
+
+
+def port_question(apps, question_text: str,
+                  answers_text: typing.Iterable[str]):
+    PersonQuestion = apps.get_model('people', 'PersonQuestion')
+
+    try:
+        prev_question = PersonQuestion.objects.filter(
+            text=question_text).latest('version')
+        question = PersonQuestion.objects.create(
+            text=question_text, version=prev_question.version + 1)
+
+    except ObjectDoesNotExist:
+        question = PersonQuestion.objects.create(text=question_text)
+
+    for answer_text in answers_text:
+        question.answers.get_or_create(text=answer_text)
+
+    return question