file_url validation

src/document/serializers.py

@@ -44,6 +44,8 @@ class DocumentSerializer(serializers.ModelSerializer):
         return obj.uploaded_by.full_name
 
     def get_file_url(self, obj):
+        if not obj.file:
+            return ""
         return f"/api/v1/documents/{obj.id}/download/"
 
     def validate_solution(self, value):
@@ -54,5 +56,6 @@ class DocumentSerializer(serializers.ModelSerializer):
             uploaded_by=profile, solution=value).count()
         if count >= _max_count:
             raise serializers.ValidationError(
-                f'You cant upload more than {_max_count} document to one solution!')
+                f'You cant upload more than {_max_count}\
+                document to one solution!')
         return value