<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _render_attributes(self, resource):
 """Render the resources's attributes."""

        attributes = {}
        attrs_to_ignore = set()

        for key, relationship in resource.__mapper__.relationships.items():
            attrs_to_ignore.update(set(
                [column.name for column in relationship.local_columns]).union(
                    {key}))

        if self.dasherize:
            mapped_fields = {x: dasherize(underscore(x)) for x in self.fields}
        else:
            mapped_fields = {x: x for x in self.fields}

        for attribute in self.fields:
            if attribute == self.primary_key:
                continue
            # Per json-api spec, we cannot render foreign keys
            # or relationsips in attributes.
            if attribute in attrs_to_ignore:
                raise AttributeError
            try:
                value = getattr(resource, attribute)
                if isinstance(value, datetime.datetime):
                    attributes[mapped_fields[attribute]] = value.isoformat()
                else:
                    attributes[mapped_fields[attribute]] = value
            except AttributeError:
                raise

        return attributes