#13693: error_messages for fields in Model don't carry over to ModelForm
-------------------------------------+-------------------------------------
Reporter: Aleks | Owner: anonymous
Type: New feature | Status: closed
Component: Forms | Version: 1.4
Severity: Normal | Resolution:
Keywords: error_messages, | worksforme
forms, models | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 1
Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
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Changes (by colegatron):
* status: reopened => closed
* resolution: => worksforme
* needs_tests: 0 => 1
* version: 1.2 => 1.4
* needs_docs: 0 => 1
* type: Uncategorized => New feature
Comment:
I am new to Django but I also think the DRY mantra should be aplicable to
the error_messages inheritance from the model to the modelform.
Perhaps by a design point of view it is not a good idea, as points Honza
in his first comment (22 months ago), but to redefine all the fields in
the modelform or form classes to get the error_messages (and perhaps other
attributes) is tedious and boilerplate.
Looking for a way to avoid this, I have find a post
(http://blog.brendel.com/2012/01/django-modelforms-setting-any-field.html)
which gives a very nice, easy and elegant way to do it.
Probably that solution can be improved, but in my opinion is candidate to
be imported as new feature in the base modelform class:
Example of use:
{{{
class AuthorForm(ExtendedMetaModelForm):
class Meta:
model = Author
field_args = {
"first_name" : {
"error_messages" : {
"required" : "Please let us know what to call you!"
}
},
"notes" : {
"+error_messages" : {
"required" : "Please also enter some notes.",
"invalid" : "This is not a valid note."
},
"widget" : forms.Textarea(attrs={'cols': 70, 'rows': 15}),
}
}
}}}
Extended modelform class:
{{{
class ExtendedMetaModelForm(forms.ModelForm):
"""
Allow the setting of any field attributes via the Meta class.
"""
def __init__(self, *args, **kwargs):
"""
Iterate over fields, set attributes from Meta.field_args.
"""
super(ExtendedMetaModelForm, self).__init__(*args, **kwargs)
if hasattr(self.Meta, "field_args"):
# Look at the field_args Meta class attribute to get
# any (additional) attributes we should set for a field.
field_args = self.Meta.field_args
# Iterate over all fields...
for fname, field in self.fields.items():
# Check if we have something for that field in field_args
fargs = field_args.get(fname)
if fargs:
# Iterate over all attributes for a field that we
# have specified in field_args
for attr_name, attr_val in fargs.items():
if attr_name.startswith("+"):
merge_attempt = True
attr_name = attr_name[1:]
else:
merge_attempt = False
orig_attr_val = getattr(field, attr_name, None)
if orig_attr_val and merge_attempt and \
type(orig_attr_val) == dict and \
type(attr_val) == dict:
# Merge dictionaries together
orig_attr_val.update(attr_val)
else:
# Replace existing attribute
setattr(field, attr_name, attr_val)
}}}
Hope this two years ticket can be closed with that nice solution.
--
Ticket URL: <https://code.djangoproject.com/ticket/13693#comment:7>
Django <https://code.djangoproject.com/>
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