django dynamic form generation - django

Question

say I have a model such:
class ComponentLength(models.Model):
component_name = models.CharField(max_length=155)
length1 = models.IntegerField()
length2 = models.IntegerField()
length3 = models.IntegerField()
length4 = models.IntegerField()
Now I have a form for the user to select a component, and on the next page I want to display 4 checkboxes for the various length options, which are different for different components.
What is the best way in Django to generate the form with these checkboxes based on the component name (accessible in session data) already selected by the user.
Any help much appreciated.

Answer 1

You could use a normal django form and change its fields upon instantiation, in the init method. Something like this:
class SecondForm(forms.Form):
def __init__(self, *args, **kwargs):
super(SecondForm, self).__init__(*args, **kwargs)
try:
#get the object, something like this:
obj_ = ComponentLength.objects.get(component_name = session.get('component_name_or_whatever_you_stored'))
except:
#handle the error case, e.g:
return
self.fields['length1'] = forms.CheckboxInput(attrs={'value' : obj_.length1 })
self.fields['length2'] = forms.CheckboxInput(attrs={'value' : obj_.length2 })
self.fields['length3'] = forms.CheckboxInput(attrs={'value' : obj_.length3 })
self.fields['length4'] = forms.CheckboxInput(attrs={'value' : obj_.length4 })
#Consider using a hidden input instead of polluting the session variables
#with form data
self.fields['component_length'] = forms.HiddenInput(attrs={'value' : obj_.pk})
The above code is not tested, but I expect it should work. Please let me know how it goes.

Answer 2

Form wizards is exactly what you need.
https://docs.djangoproject.com/en/1.7/ref/contrib/formtools/form-wizard/
See the example shown here https://docs.djangoproject.com/en/1.7/ref/contrib/formtools/form-wizard/#usage-of-namedurlwizardview
And how forms are defined here https://docs.djangoproject.com/en/1.7/ref/contrib/formtools/form-wizard/#conditionally-view-skip-specific-steps
I haven't tested the code below, but it should be something similar to the following:
myapp/forms.py
from django.forms import ModelForm
from myapp.models import ComponentLength
class ComponentLengthNameForm(ModelForm):
class Meta:
model = ComponentLength
fields = ['component_name',]
class ComponentLengthChoicesForm(ModelForm):
class Meta:
model = ComponentLength
fields = ['length1', 'length2', 'length3', 'length4',]
myapp/views.py
from django.contrib.formtools.wizard.views import SessionWizardView
from django.shortcuts import render_to_response
class ComponentWizard(SessionWizardView):
def done(self, form_list, **kwargs):
return render_to_response('done.html', {
'form_data': [form.cleaned_data for form in form_list],
})
myapp/urls.py
from django.conf.urls import url, patterns
from myapp.forms import ComponentLengthNameForm, ComponentLengthChoicesForm
from myapp.views import ContactWizard
named_contact_forms = (
('name', ComponentLengthNameForm),
('length-choices', ComponentLengthChoicesForm),
)
component_wizard = ComponentWizard.as_view(named_contact_forms,
url_name='component-wizard-form-step', done_step_name='finished')
urlpatterns = patterns('',
url(r'^my-form/(?P<step>.+)/$', component_wizard, name='component-wizard-form-step'),
url(r'^my-form/$', component_wizard, name='component-wizard-form'),
)