Am 08.03.2006 um 16:20 schrieb Joseph Kocherhans:
> The short version of this is really, forms and manipulators merge and
> get more powerful, models grow validation. This is an attempt to
> clarify and add to Adrian's previous proposal. I hope it takes care of
> people's concerns. Here are some details:
>
> Forms and FormFields are intended to be used for web applications
> only. Models do validation, so using forms isn't necessary when
> manipulating data directly in python. Also, I think something similar
> to this would allow for recursive forms (edit_inline behavior), but I
> haven't worked out all the details.
>
> Models would grow a validate method and validate=True is added as an
> argument to Model's save methods. Models would not do any type
> coercion. (I guess they could, but I think most type coercion should
> happen in the form fields, not the model fields.)
Agreed. Models should expect the correct Python types, coercion from
strings/whatever should be in the web layer.
> I'm ignoring a bunch of metaclass magic that needs to go on here, but
> I hope the intentions are clear. Bring on the pseudocode...
>
>
> class Form(object):
> def __init__(self, request, prefix=''):
> self.request = request
> # prefix corresponds to a prefix to http variable names.
> The prefix
> # should be used to strip off the first part of the var names.
> # Hopefully this will allow for recursively defined
> forms... in other
> # words, edit_inline is available outside of the admin system.
> self.prefix = prefix
> # this would actually be more complicated... use prefix to
> get a dict
> # of strings for the form fields to coerce.
> self.data = request.POST.copy()
>
> def _get_model_obj(self):
> """
> return the cached model object, or init/cache/return one.
> """
>
> model = property(_get_model_obj)
So how is a Form connected to a Model?
> def set_defaults(self):
> """
> Call get_default() (hopefully passing in self.request) on each
> FormField, and set the appropriate attributes on self.model.
> """
>
> def validate(self):
> """
> Basically just return self.model.validate(). Call validate
> for child
> forms as well.
> """
>
> def save(self, validate=True):
> """
> Basically just call self.model.save(validate=validate) Call
> save for
> child forms as well.
> """
>
> def html(self):
> """
> This is really just convenience for people who are too lazy
> to write
> real templates. Returns a very generic form redered as
> html. It
> should probably have enough css hooks to make it workable
> though. It
> is meant to be called in a template like {{ form.html }}
> """
Maybe this would be better implemented as a template tag?
> class ArticleAddForm(Form):
> # author will not be editable or displayed
> exclude_fields = ('author',)
> extend_fields = (
> formfields.EmailField(field_name="from", is_required=True),
> )
>
> class ArticleChangeForm(Form):
> # author will be displayed, but not editable
> readonly_fields = ('author',)
>
> class Article(models.Models):
> name = models.CharField(maxlength=100)
> body = models.TextField()
> author = models.AuthorField()
>
> class Meta:
> # this gets used in generic create views
> add_form = ArticleAddForm
>
> class Admin:
> # this gets used in the admin system
> change_form = ArticleChangeForm
>
>
> # Usage:
> def myview(request):
> add_form = Article.AddForm(request)
> errors = add_form.validate()
> if not errors:
> add_form.save(validate=False)
> return HttpResponseRedirect('the_next_page')
> ctx = RequestContext({'form': add_form})
> return render_to_response('template', ctx)
>
>
> I hope something like this will come out of Adrian's validation aware
> model proposal. This would solve those issues, and add a ton of
> flexibility to Django. There are many details that need to be pinned
> down, but I think something like this should be workable.
>
> Also, there are things that I've probably overlooked. What are they?
I've probably missed some of the previous discussion, but does all
this mean that Manipulators would go away completely?
Cheers,
Chris
--
Christopher Lenz
cmlenz at gmx.de
http://www.cmlenz.net/
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