- realmente tem que ter estruturas individuais de ``try...except``
- o ``ValueError`` capturado no ``try ... except`` assim esta certo, como pode ver e reproduzir a exceção como esse código aqui:
```python
>>> from journalmanager.models import Journal
>>> j = Journal()
>>> j.cover
<FieldFile: None>
>>> j.cover.url
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/Users/juan.funez/Work/Code/scielo.org/scielo-manager/lib/python2.7/site-packag
es/django/db/models/fields/files.py", line 63, in _get_url
    self._require_file()
  File "/Users/juan.funez/Work/Code/scielo.org/scielo-manager/lib/python2.7/site-packag
es/django/db/models/fields/files.py", line 41, in _require_file
    raise ValueError("The '%s' attribute has no file associated with it." % self.field.
name)
ValueError: The 'cover' attribute has no file associated with it.
>>>
```