django.core.exceptions.ValidationError is poorly implemented and documented
|Reported by:||tomevans223||Owned by:||nobody|
|Cc:||Triage Stage:||Design decision needed|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
django.core.exceptions.ValidationError has a horrific interface. It's publicly accessible attributes differ depending upon how the object is created, as do the pre/post conditions for it's publicly accessible methods.
If constructed with a dictionary of error messages, then it gets an attribute 'message_dict'.
If constructed with a string, or a list of strings, then it gets an attribute 'messages'.
The documentation on Model.clean() talks about ValidationError, but does not mention this at all, and instructs the user to look at messages_dict. 
If constructed with a dictionary of error messages, then the method update_error_dict(self, error_dict) will happily accept error_dict=None - it checks for and handles this condition. If constructed with a string or list, then not supplying error_dict is an error.
This sort of inconsistent behaviour is hard to explain. At the least, this behaviour should be documented clearly, but ideally the interface should be consistent, regardless of how it is constructed.
Change History (5)
comment:2 Changed 5 years ago by
|Patch needs improvement:||unset|
|Triage Stage:||Unreviewed → Design decision needed|