gistfile1.py

def get_chained_select_choices(content_type, depth=1, with_field_types=False):
    """ Gets field names from the content_type.
        depth=1 means return any fk or manytomany fields as well
        TODO: depth>1 is not implemented yet
    """
    if depth > 1:
        raise Exception("depth should be 0 or 1")

    # helpers
    model_klass = content_type.model_class()
    model_to_fields = defaultdict(list)

    # dict model -> fields related to that model
    for fld in (model_klass._meta.fields + model_klass._meta.many_to_many):
        if fld.rel:
            model_to_fields[fld.rel.to].append(fld)
    model_to_fields = dict(model_to_fields)
    all_fields = sum(model_to_fields.values(), [])

    # names of fields available on form
    fields_on_form = set(content_type.config.modelfield_set.values_list('fieldname', flat=True))

    def flatelizer(fields):
        # go thrue every field in model
        for fld in fields:
            # if it's foreing key and visible on form
            if fld.rel and fld.name in fields_on_form:
                # get all related for that field
                for subfield in fld.rel.to._meta.fields + fld.rel.to._meta.many_to_many:
                    # if it's related
                    if subfield.rel:
                        # subsubfield.rel.to should pointing to any field on form, it its correct
                        # that pointed field can filter subsubfield by subfield filter
                        for subsubfield in model_to_fields.get(subfield.rel.to, []):
                            # if fld.name != subsubfield.name and subfield:
                            if fld.name != subsubfield.name:
                                yield subsubfield.name, subfield.name, fld.name,
    tmp = defaultdict(list)
    for parent, filter_by, fld_name in flatelizer(all_fields):
        tmp[parent].append([filter_by, fld_name])
    choices = []
    for parent, subfields in tmp.iteritems():
        if len(subfields)==1:
            choices.append(('{0}__{1}'.format(parent, subfields[0][0], '{0} fld: {1}'.format(parent, subfields[0][1], False, False, False))))
        else:
            for filtered_by, fld_name in subfields:
                choices.append(('{0}__{1}'.format(parent, filtered_by), '{0} ({1}) fld: {2}'.format(parent, filtered_by, fld_name)))

    #choices = [(relative_field, relative_field.replace('__', ' → '), '', False, False, ('.field-fieldname select', for_field)) for relative_field, for_field in flatelizer(all_fields)]

    return tuple(choices)