[Question]: RouterQueryEngine what is recommended way to access selected engine?

[h1Logic]

Question Validation

• I have searched both the documentation and discord for an answer.

Question

Hi,

what is recommended way to access selected tool/engine in RouterQueryEngine? As far as i can tell it's only logged via logger.info() but it's not stored anywhere. It would be great if either it can be returned or stored as property (or example 'last_selected_engine_ind`).

Thanks!

[dosubot[bot]]

🤖

Hi,

You're correct that the RouterQueryEngine currently does not store or provide a method to access the selected tool/engine. The selected tool/engine is determined within the _query and _aquery methods by the self._selector.select method, but it is not stored or accessible outside of these methods.

If you need to access the selected tool/engine, one possible solution could be to modify the RouterQueryEngine class to store the selected tool/engine as a property. Here's a simple example of how you might do this:

class RouterQueryEngine(BaseQueryEngine):
    # existing code...

    def _query(self, query: Query) -> Any:
        # existing code...
        self.last_selected_engine_ind = self._selector.select(query, self._query_engine_tools)
        selected_tool = self._query_engine_tools[self.last_selected_engine_ind]
        # existing code...

    def _aquery(self, query: Query) -> Any:
        # existing code...
        self.last_selected_engine_ind = self._selector.select(query, self._query_engine_tools)
        selected_tool = self._query_engine_tools[self.last_selected_engine_ind]
        # existing code...

In this example, last_selected_engine_ind is a new property on the RouterQueryEngine class that stores the index of the last selected tool/engine. You can then access this property to see which tool/engine was selected for the last query.

Please note that this is a simple example and may not cover all use cases or edge cases. You may need to adjust this code to fit your specific needs.

I hope this helps! Let me know if you have any other questions.

Sources

• llama_index/query_engine/router_query_engine.py

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[h1Logic]

Such approach requires to sync custom implementation with any changes made RouterQueryEngine class (since it's not possible to call super().query()) - would it be feasible to prepare MR with such feature so it might be officially supported? (I could prepare such MR by myself)

[logan-markewich]

@h1Logic I think ideally this would get logged either in the response object (response.metadata?) or would be part of our callback-based event logging.