[Bug]: The graph_query_synthesis_prompt parameter of KnowledgeGraphRAGRetriever

[codeinging]

Bug Description

According to the official documentation, “nl2graphquery” can not be included as Context in Graph RAG, Reason may be that the absence of "graph_query_synthesis_prompt" parameter! However, in the official documentation and source code, this parameter is optional. I manually add this parameter, and the problem is solved!

Version

0.10.29

Steps to Reproduce

`graph_rag_retriever_with_nl2graphquery = KnowledgeGraphRAGRetriever( storage_context=storage_context, verbose=True, with_nl2graphquery=True, )

query_engine_with_nl2graphquery = RetrieverQueryEngine.from_args( graph_rag_retriever_with_nl2graphquery, )`

Relevant Logs/Tracbacks

No response

[dosubot[bot]]

The issue you encountered with the KnowledgeGraphRAGRetriever and the "nl2graphquery" context arises from the implementation specifics of the KnowledgeGraphQueryEngine. When the graph_query_synthesis_prompt parameter is not manually specified, the engine defaults to using a prompt template from DEFAULT_NL2GRAPH_PROMPT_MAP based on the graph store type. This default behavior means that any custom "nl2graphquery" context or contexts not predefined require the graph_query_synthesis_prompt to be explicitly provided during initialization.

The source code indicates that the KnowledgeGraphQueryEngine class initializes its _graph_query_synthesis_prompt attribute with a value from this map unless the graph_query_synthesis_prompt is provided. This is why manually adding this parameter resolves the issue.

Furthermore, the engine's reliance on the storage_context to determine the graph store type underscores the importance of providing a storage_context with a graph_store during initialization. The engine asserts the presence of a graph_store in the storage_context, which is crucial for its operation.

This behavior, while logical from a coding perspective, could benefit from clearer documentation to help users understand the necessity of manually specifying the graph_query_synthesis_prompt for custom contexts. This clarification could prevent similar confusion in the future and improve the user experience with the KnowledgeGraphRAGRetriever.

Sources

• llama-index-legacy/llama_index/legacy/query_engine/knowledge_graph_query_engine.py
• llama-index-core/llama_index/core/query_engine/knowledge_graph_query_engine.py

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