options.py 文件源码

def lookup_allowed(self, lookup, value):
        model = self.model
        # Check FKey lookups that are allowed, so that popups produced by
        # ForeignKeyRawIdWidget, on the basis of ForeignKey.limit_choices_to,
        # are allowed to work.
        for l in model._meta.related_fkey_lookups:
            for k, v in widgets.url_params_from_lookup_dict(l).items():
                if k == lookup and v == value:
                    return True

        parts = lookup.split(LOOKUP_SEP)

        # Last term in lookup is a query term (__exact, __startswith etc)
        # This term can be ignored.
        if len(parts) > 1 and parts[-1] in QUERY_TERMS:
            parts.pop()

        # Special case -- foo__id__exact and foo__id queries are implied
        # if foo has been specifically included in the lookup list; so
        # drop __id if it is the last part. However, first we need to find
        # the pk attribute name.
        rel_name = None
        for part in parts[:-1]:
            try:
                field, _, _, _ = model._meta.get_field_by_name(part)
            except FieldDoesNotExist:
                # Lookups on non-existent fields are ok, since they're ignored
                # later.
                return True
            if hasattr(field, 'rel'):
                if field.rel is None:
                    # This property or relation doesn't exist, but it's allowed
                    # since it's ignored in ChangeList.get_filters().
                    return True
                model = field.rel.to
                rel_name = field.rel.get_related_field().name
            elif isinstance(field, RelatedObject):
                model = field.model
                rel_name = model._meta.pk.name
            else:
                rel_name = None
        if rel_name and len(parts) > 1 and parts[-1] == rel_name:
            parts.pop()

        if len(parts) == 1:
            return True
        clean_lookup = LOOKUP_SEP.join(parts)
        return clean_lookup in self.list_filter or clean_lookup == self.date_hierarchy