Add deadline validation to homework

src/homework/migrations/0012_auto_20180404_1253.py

+# Generated by Django 2.0.1 on 2018-04-04 10:53
+
+import common.validators
+import django.core.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('homework', '0011_auto_20180404_0853'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='solution',
+            name='files',
+            field=models.FileField(upload_to='', validators=[django.core.validators.FileExtensionValidator(['image/png', 'image/jpeg', 'zip']), common.validators.FileSizeValidator(size_limit=52428800)]),
+        ),
+    ]

src/homework/models.py

@@ -42,5 +42,4 @@ class Solution(models.Model):
             ]),
             FileSizeValidator(size_limit=52428800),  # 52428800 - 50MiB
         ],
-        blank=True,
     )

src/homework/serializers.py

 from rest_framework import serializers
+from django.utils import timezone
 
 from common.serializers import CurrentUserProfileDefault
 from . import models
@@ -21,3 +22,8 @@ class SolutionSerializer(serializers.ModelSerializer):
         model = models.Solution
         read_only_fields = ('created_by', 'date' 'ready')
         fields = ('task', 'date', 'accepted', 'files', 'created_by')
+
+    def validate(self, data):
+        if timezone.now() > data['task'].deadline:
+            raise serializers.ValidationError('You late.')
+        return data