.

longs/models.py

@@ -141,8 +141,13 @@ class Long(models.Model):
     # return self.GetImages()
 
 
+def test_image_validator(file):
+    if 100 == 200:
+        raise ValidationError("Error")
+    return True
+
 class LongSeriesImage(models.Model):
-    image = models.ImageField(upload_to=image_directory_path, storage=image_storage)
+    image = models.ImageField(upload_to=image_directory_path, storage=image_storage, validators=[test_image_validator])
     position = models.IntegerField(default=0)
     series = models.ForeignKey(
         "LongSeries", related_name="images", on_delete=models.SET_NULL, null=True