migrate to postgres json field

contest/migrations/0006_auto_20171011_1214.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-10-11 12:14
+from __future__ import unicode_literals
+
+import django.contrib.postgres.fields.jsonb
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contest', '0005_auto_20170823_0918'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='acmcontestrank',
+            name='submission_info',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict),
+        ),
+        migrations.AlterField(
+            model_name='oicontestrank',
+            name='submission_info',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict),
+        ),
+    ]

contest/models.py

@@ -1,7 +1,7 @@
 from utils.constants import ContestRuleType  # noqa
 from django.db import models
 from django.utils.timezone import now
-from jsonfield import JSONField
+from utils.models import JSONField
 
 from utils.constants import ContestStatus, ContestType
 from account.models import User, AdminType
@@ -65,7 +65,7 @@ class ACMContestRank(AbstractContestRank):
     total_time = models.IntegerField(default=0)
     # {23: {"is_ac": True, "ac_time": 8999, "error_number": 2, "is_first_ac": True}}
     # key is problem id
-    submission_info = JSONField(default={})
+    submission_info = JSONField(default=dict)
 
     class Meta:
         db_table = "acm_contest_rank"
@@ -75,7 +75,7 @@ class OIContestRank(AbstractContestRank):
     total_score = models.IntegerField(default=0)
     # {23: 333}}
     # key is problem id, value is current score
-    submission_info = JSONField(default={})
+    submission_info = JSONField(default=dict)
 
     class Meta:
         db_table = "oi_contest_rank"