fix error when captcha picture is lost & add unique to the captcha key field

Author: szdytom

captcha/migrations/0004_auto_20200731_1026.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1rc1 on 2020-07-31 02:26
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('captcha', '0003_auto_20200729_2208'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='captchastore',
+            name='key',
+            field=models.IntegerField(unique=True),
+        ),
+    ]

captcha/models.py

@@ -6,7 +6,7 @@
 
 # Create your models here.
 class CaptchaStore(models.Model):
-	key = models.IntegerField()
+	key = models.IntegerField(unique=True)
 	answer = models.CharField(max_length=10)
 	added_time = models.DateTimeField(auto_now=True)
 
@@ -17,6 +17,9 @@ def clean_expire(self):
 		expired_data = self.objects.filter(added_time__gte=tools.settimelater(timezone.now()))
 		for edata in expired_data:
 			path = os.path.join(settings.BASE_DIR, "uploads", "captcha", "{name}.png".format(name=edata.key))
-			os.remove(path)
+			try:
+				os.remove(path)
+			except FileNotFoundError:
+				pass
 
 			edata.delete()