Arbitrary length formset

from django import forms

from django import forms
from django.forms.util import ErrorDict, ErrorList
from django.utils.encoding import force_unicode, smart_unicode
from django.utils.safestring import mark_safe

class Form(forms.Form):

    def add_error(self, field_name, message):
        if field_name is None: field_name = forms.NON_FIELD_ERRORS
        # self.errors is checked first because it triggers self.clean_all
        # but only if self._errors is None
        if self.errors is None:
            self._errors = ErrorDict()
        message = smart_unicode(message)
        messages = ErrorList([message])
        if not self._errors.has_key(field_name):
            self._errors[field_name] = messages
        else:
            self._errors[field_name].extend(messages)

    def all_errors(self):
        if self.errors == {}: return None
        self.errors['%sALL' % forms.NON_FIELD_ERRORS] = ErrorList()
        for k in self.errors:
            self.errors['%sALL' % forms.NON_FIELD_ERRORS].extend(self.errors[k])
        return self.errors.get('%sALL' % forms.NON_FIELD_ERRORS, self.error_class())


class XManagementForm(forms.formsets.ManagementForm):
    """
    ``ManagementForm`` is used to keep track of how many form instances
    are displayed on the page. If adding new forms via javascript, you should
    increment the count field of this form as well.
    """
    def __init__(self, data=None, extra_fields=None, *args, **kwargs):
        for f, tv in extra_fields.items():
            self.base_fields[f] = tv[0](widget=forms.HiddenInput)
            if kwargs.has_key('initial'):
                kwargs['initial'][f] = tv[1]
        super(XManagementForm, self).__init__(data, *args, **kwargs)


class BaseXFormSet(forms.formsets.BaseFormSet):

    def __init__(self, *args, **kwargs):
        self.added_forms = 0
        super(BaseXFormSet, self).__init__(*args, **kwargs)

    def _management_form(self):
        """Returns the ManagementForm instance for this FormSet."""
        if self.data or self.files:
            form = XManagementForm(self.data, auto_id=self.auto_id, prefix=self.prefix,
                extra_fields=self.extra_fields)
            #import pdb; pdb.set_trace()
            if not form.is_valid():
                raise forms.ValidationError('ManagementForm data is missing or has been tampered with')
        else:
            form = XManagementForm(auto_id=self.auto_id, prefix=self.prefix, extra_fields=self.extra_fields,
                initial={
                    forms.formsets.TOTAL_FORM_COUNT: self.total_form_count(),
                    forms.formsets.INITIAL_FORM_COUNT: self.initial_form_count()
            })
        return form
    management_form = property(_management_form)

    def initial_form_count(self):
        """Returns the number of forms that are required/pre-populated in this FormSet."""
        if not (self.data or self.files):
            initial_forms = self.initial and len(self.initial) or 0
            initial_forms += self.added_forms
            if initial_forms > self.max_num > 0:
                initial_forms = self.max_num
            return initial_forms
        return super(BaseXFormSet, self).initial_form_count()

    def add_form(self, existing_form=None, **kwargs):
        self.added_forms = self.added_forms + 1
        l_curIdx = len(self.forms)
        if existing_form:
            l_new_form = existing_form
            l_new_form.prefix = self.add_prefix(l_curIdx)
        else:
            l_new_form = self._construct_form(l_curIdx, **kwargs)
        l_new_form.form_index = l_curIdx
        self.forms.append(l_new_form)
        return l_new_form

def formset_factory(form, formset=BaseXFormSet, extra=0, can_order=False,
                    can_delete=False, max_num=0, extra_fields=None):
    """Return a FormSet for the given form class."""
    attrs = {'form': form, 'extra': extra,
             'can_order': can_order, 'can_delete': can_delete,
             'max_num': max_num, 'extra_fields': extra_fields}
    return type(form.__name__ + 'FormSet', (formset,), attrs)