CohereAPIError thrown when base retriever returns empty documents in ContextualCompressionRetriever using Cohere Rank

[hanguofeng]

System Info

• 5.19.0-42-generic # 43~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Apr 21 16:51:08 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
• langchain==0.0.180
• Python 3.10.11

Who can help?

No response

Information

• The official example notebooks/scripts
• My own modified scripts

Related Components

• LLMs/Chat Models
• Embedding Models
• Prompts / Prompt Templates / Prompt Selectors
• Output Parsers
• Document Loaders
• Vector Stores / Retrievers
• Memory
• Agents / Agent Executors
• Tools / Toolkits
• Chains
• Callbacks/Tracing
• Async

Reproduction

1. Set up a retriever using any type of retriever (for example, I used Pinecone).
2. Pass it into the ContextualCompressionRetriever.
3. If the base retriever returns empty documents,
4. It throws an error: cohere.error.CohereAPIError: invalid request: list of documents must not be empty

File "/workspaces/example/.venv/lib/python3.10/site-packages/langchain/retrievers/contextual_compression.py", line 37, in get_relevant_documents
compressed_docs = self.base_compressor.compress_documents(docs, query)
File "/workspaces/example/.venv/lib/python3.10/site-packages/langchain/retrievers/document_compressors/cohere_rerank.py", line 57, in compress_documents
results = self.client.rerank(
File "/workspaces/example/.venv/lib/python3.10/site-packages/cohere/client.py", line 633, in rerank
reranking = Reranking(self._request(cohere.RERANK_URL, json=json_body))
File "/workspaces/example/.venv/lib/python3.10/site-packages/cohere/client.py", line 692, in _request
self._check_response(json_response, response.headers, response.status_code)
File "/workspaces/example/.venv/lib/python3.10/site-packages/cohere/client.py", line 642, in _check_response
raise CohereAPIError(
cohere.error.CohereAPIError: invalid request: list of documents must not be empty

Code is Like

 
retriever = vectorstore.as_retriever()
compressor = CohereRerank()
compression_retriever = ContextualCompressionRetriever(
    base_compressor=compressor, base_retriever=retriever
)
return compression_retriever

Expected behavior

no error throws and return empty list

[dev2049]

good catch! happy to review if you want to open a fix, otherwise can get to it this weekend

[dev2049]

ah see you already opened!