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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