Method _generate_cache_key

lib/sqlalchemy/sql/cache_key.py:349–393

return a cache key. The cache key is a tuple which can contain any series of objects that are hashable and also identifies this object uniquely within the presence of a larger SQL expression or statement, for the purposes of caching the resulting query. The

(self)

        return result

    def _generate_cache_key(self) -> Optional[CacheKey]:
        """return a cache key.

        The cache key is a tuple which can contain any series of
        objects that are hashable and also identifies
        this object uniquely within the presence of a larger SQL expression
        or statement, for the purposes of caching the resulting query.

        The cache key should be based on the SQL compiled structure that would
        ultimately be produced.   That is, two structures that are composed in
        exactly the same way should produce the same cache key; any difference
        in the structures that would affect the SQL string or the type handlers
        should result in a different cache key.

        The cache key returned by this method is an instance of
        :class:`.CacheKey`, which consists of a tuple representing the
        cache key, as well as a list of :class:`.BindParameter` objects
        which are extracted from the expression.   While two expressions
        that produce identical cache key tuples will themselves generate
        identical SQL strings, the list of :class:`.BindParameter` objects
        indicates the bound values which may have different values in
        each one; these bound parameters must be consulted in order to
        execute the statement with the correct parameters.

        a :class:`_expression.ClauseElement` structure that does not implement
        a :meth:`._gen_cache_key` method and does not implement a
        :attr:`.traverse_internals` attribute will not be cacheable; when
        such an element is embedded into a larger structure, this method
        will return None, indicating no cache key is available.

        """

        bindparams: List[BindParameter[Any]] = []

        _anon_map = anon_map()
        key = self._gen_cache_key(_anon_map, bindparams)
        if NO_CACHE in _anon_map:
            return None
        else:
            assert key is not None
            return CacheKey(
                key,
                bindparams,
                _anon_map.get(CacheConst.PARAMS),  # type: ignore[arg-type]
            )


class HasCacheKeyTraverse(HasTraverseInternals, HasCacheKey):