support display id

contest/migrations/0002_auto_20170209_0845.py

@@ -0,0 +1,29 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.12 on 2017-02-09 08:45
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contest', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='contestproblem',
+            name='_id',
+            field=models.CharField(db_index=True, default='1', max_length=24),
+            preserve_default=False,
+        ),
+        migrations.RemoveField(
+            model_name='contestproblem',
+            name='sort_index',
+        ),
+        migrations.AlterUniqueTogether(
+            name='contestproblem',
+            unique_together=set([('_id', 'contest')]),
+        ),
+    ]