Hi,
Interesting. I've never heard of someone wanting to show validation errors
on the initial data when the page first loads.
I have however wanted to manually bind data to a form before. Last time I
checked it's not super trivial, because you could for instance have a
SplitDateTimeWidget which actually expects _two_ keys in the bound data.
If you're just doing basic fields, that should work. If you're doing
anything more complicated, it might make sense to run the validation more
by hand. If you could call field.clean() on the less raw data you could
skip widgets and prefixes all together.
Collin
On Tuesday, January 20, 2015 at 8:06:06 AM UTC-5, Rob Groves wrote:
>
> Hi All,
> I am new to Django and am enjoying it very much. Excellent documentation,
> tutorials, and general environment to work in. Good job Django developers!
>
> I have a question on binding data to a ModelFormset. I have looked
> extensively and not seen this particular issue covered before.
>
> I have a ModelFormset that I send to a template for custom rendering so I
> can present the fields in a controlled tabular format. The ultimate goal
> is to use CSS to create a red bounding box around any fields with
> validation errors and to set the "title" attribute of those input fields so
> that the user can see what errors were generated by hovering over the red
> bounded field. This presents a nice clean interface when there are
> errors. It all works great, with one annoyance if the model data starts
> out with values that will generate validation errors (i.e. missing required
> data).
>
> I initially call the view with a GET, which creates the forms and
> populates the form fields. Since the data is not bound to forms at this
> point, I can't validate and set the errors. In order to validate the
> fields and set the table error borders, I have to submit the form using
> POST to bind the data, validate the form and generate the errors which
> ultimately set an error_class for styling the table. This means that I
> have to "save" the from from my form page to get the table style I want.
>
> What I really want is to instantiate a ModelFormset, setting the instance,
> but then to bind the data present in the instance and set errors by sending
> is_valid() to the formset before rendering (i.e. on initial page rendering
> with the GET, so no POST data). It seemed to me that there should simply
> be a bind_instance() function for all ModelFormsets that contain an
> instance. I looked and didn't find that. Eventually, I just decided to
> bind the data myself manually using the following helper function:
>
> # helper functions
> def bind_formset(formset):
> bindData={}
> # add management form data
> bindData[formset.get_default_prefix()+"-TOTAL_FORMS"]=str(formset.
> management_form['TOTAL_FORMS'].value())
> bindData[formset.get_default_prefix()+"-INITIAL_FORMS"]=str(formset.
> management_form['INITIAL_FORMS'].value())
> bindData[formset.get_default_prefix()+"-MIN_NUM_FORMS"]=str(formset.
> management_form['MIN_NUM_FORMS'].value())
> bindData[formset.get_default_prefix()+"-MAX_NUM_FORMS"]=str(formset.
> management_form['MAX_NUM_FORMS'].value())
> for form in formset:
> if form.instance:
> for fieldName,fieldValue in form.fields.iteritems():
> try:
> bindData[form.add_prefix(fieldName)]=getattr(form.
> instance,fieldName)
> except:
> # this is an added field, not derived from the model
> pass
> newFormset=formset.__class__(bindData,instance=formset.instance,
> queryset=formset.queryset, error_class=
> formset.error_class)
> return newFormset
>
> This works! My question... Is this a reasonable approach? Or did I just
> miss the obvious way of doing this?
>
> Thanks for any help!
>
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