def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
        # Aggregates are not allowed in UPDATE queries, so ignore for_save
        c = super(Aggregate, self).resolve_expression(query, allow_joins, reuse, summarize)
        if not summarize:
            expressions = c.get_source_expressions()
            for index, expr in enumerate(expressions):
                if expr.contains_aggregate:
                    before_resolved = self.get_source_expressions()[index]
                    name = before_resolved.name if hasattr(before_resolved, 'name') else repr(before_resolved)
                    raise FieldError("Cannot compute %s('%s'): '%s' is an aggregate" % (c.name, name, name))
        return c
dataset/ETHPy150Open django/django/django/db/models/aggregates.py/Aggregate.resolve_expression/original