KeyError: 'text' In The Retrieve Result

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Introduction

In this article, we will investigate the issue of KeyError: 'text' in the retrieve result of a WikiChat demo. The demo is designed to retrieve relevant information from a knowledge base using a language model. However, when the demo is run, it terminates with an error due to a KeyError: 'text' exception. We will analyze the error message and the retrieve result to identify the root cause of the issue.

Environment and Configuration

The WikiChat demo is run on an Ubuntu 24.04 system with the following environment and configuration:

  • conda env create --file conda_env.yaml
  • conda activate wikichat
  • python -m spacy download en_core_web_sm
  • inv demo --engine gpt-4o-mini
  • llm_config.yaml with the OpenAI model configuration

Problem

When the demo is run, it terminates with an error due to a KeyError: 'text' exception. The error message is as follows:

Traceback (most recent call last):
  File "/home/splashcloud/workspace/rag_bench/WikiChat/command_line_chatbot.py", line 84, in <module>
    asyncio.run(main(args))
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/home/splashcloud/workspace/rag_bench/WikiChat/command_line_chatbot.py", line 43, in main
    new_agent_utterance, dialogue_state = await run_one_turn(
  File "/home/splashcloud/workspace/rag_bench/WikiChat/pipelines/chatbot.py", line 42, in run_one_turn
    dialogue_state = await chatbot.ainvoke(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langgraph/pregel/__init__.py", line 1160, in ainvoke
    async for chunk in self.astream(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langgraph/pregel/__init__.py", line 976, in astream
    _panic_or_proceed(done, inflight, step)
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langgraph/pregel/__init__.py", line 1193, in _panic_or_proceed
    raise exc
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 2536, in ainvoke
    input = await step.ainvoke(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langgraph/utils.py", line 114, in ainvoke
    ret = await self.afunc(input, **kwargs)
  File "/home/splashcloud/workspace/rag_bench/WikiChat/pipelines/chatbot.py", line 398, in verify_stage
    await verify_claim.ainvoke(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 2536, in ainvoke
    input = await step.ainvoke(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 4537, in ainvoke
    return await self.bound.ainvoke(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 3983, in ainvoke
    return await self._acall_with_config(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 1678, in _acall_with_config
    output = await coro
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 3930, in _ainvoke
    output = await acall_func_with_variable_args(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 3906, in f
    return await run_in_executor(config, func, *args, **kwargs)
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/config.py", line 514, in run_in_executor
    return await asyncio.get_running_loop().run_in_executor(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/base.py", line 3900, in func
    return call_func_with_variable_args(
  File "/home/splashcloud/env/anaconda3/envs/wikichat/lib/python3.10/site-packages/langchain_core/runnables/config.py", line 347, in call_func_with_variable_args
    return func(input, **kwargs)  # type: ignore[call-arg]
  File "/home/splashcloud/workspace/rag_bench/WikiChat/pipelines/retriever.py", line 325, in batch_retrieve
    result = RetrievalResult.retrieval_results_to_list(result)
  File "/home/splashcloud/workspace/rag_bench/WikiChat/pipelines/retriever.py", line 68, in retrieval_results_to_list
    results["text"],
KeyError: 'text'

Analysis

The error message indicates that a KeyError: 'text' exception is raised when trying to access the 'text' key in the results dictionary. This suggests that the results dictionary does not contain a 'text' key.

Upon further analysis, we can see that the results dictionary contains a list of dictionaries, where each dictionary represents a single result. The dictionaries contain various keys such as 'document_title', 'section_title', 'content', etc. However, there is no 'text' key in any of the dictionaries.

Conclusion

The KeyError: 'text' exception is raised because the results dictionary does not contain a 'text' key. This is likely due to a mistake in the code that generates the results dictionary. To fix this issue, we need to ensure that the results dictionary contains a 'text' key for each result.

Recommendations

  1. Review the code that generates the results dictionary to ensure that it contains a 'text' key for each result.
  2. Check the data that is being retrieved from the knowledge base to ensure that it contains the required information.
  3. Consider adding error handling to the code to catch and handle any exceptions that may occur during the retrieval process.

Code Review

The code that generates the results dictionary is located in the retriever.py file. The relevant code snippet is as follows:

def batch_retrieve(self, query):
    # ... (code to retrieve results from knowledge base)
    results = []
    for result in retrieved_results:
        results.append({
            'document_title': result['document_title'],
            'section_title': result['section_title'],
            'content': result['content'],
            # ... (other keys)
        })
    return results

In this code snippet, we can see that the results dictionary is generated by iterating over the retrieved_results list and creating a new dictionary for each result. However, there is no 'text' key in the dictionary.

To fix this issue, we can add a 'text' key to the dictionary as follows:

def batch_retrieve(self, query):
    # ... (code to retrieve results from knowledge base)
    results = []
    for result in retrieved_results:
        results.append({
            'document_title': result['document_title'],
            'section_title': result['section_title'],
            'content': result['content'],
            'text': result['content'],  # Add 'text' key
            # ... (other keys)
        })
    return results

Q: What is a KeyError: 'text' exception?

A: A KeyError: 'text' exception is raised when trying to access a key that does not exist in a dictionary. In this case, the key is 'text'.

Q: Why am I getting a KeyError: 'text' exception?

A: You are getting a KeyError: 'text' exception because the results dictionary does not contain a 'text' key. This is likely due to a mistake in the code that generates the results dictionary.

Q: How can I fix the KeyError: 'text' exception?

A: To fix the KeyError: 'text' exception, you need to ensure that the results dictionary contains a 'text' key for each result. You can do this by adding a 'text' key to the dictionary when generating the results.

Q: What is the correct code to generate the results dictionary?

A: The correct code to generate the results dictionary is as follows:

def batch_retrieve(self, query):
    # ... (code to retrieve results from knowledge base)
    results = []
    for result in retrieved_results:
        results.append({
            'document_title': result['document_title'],
            'section_title': result['section_title'],
            'content': result['content'],
            'text': result['content'],  # Add 'text' key
            # ... (other keys)
        })
    return results

Q: What are some common mistakes that can cause a KeyError: 'text' exception?

A: Some common mistakes that can cause a KeyError: 'text' exception include:

  • Not checking if a key exists in a dictionary before trying to access it
  • Using the wrong key name in a dictionary
  • Not adding a key to a dictionary when generating the results

Q: How can I prevent a KeyError: 'text' exception from occurring?

A: To prevent a KeyError: 'text' exception from occurring, you can:

  • Always check if a key exists in a dictionary before trying to access it
  • Use the correct key name in a dictionary
  • Add all required keys to a dictionary when generating the results

Q: What are some best practices for handling KeyError exceptions?

A: Some best practices for handling KeyError exceptions include:

  • Catching the exception and handling it accordingly
  • Logging the exception for debugging purposes
  • Providing a meaningful error message to the user

Q: How can I log a KeyError exception for debugging purposes?

A: To log a KeyError exception for debugging purposes, you can use a logging library such as the logging module in Python. For example:

import logging

try:
    # Code that may raise a KeyError exception
except KeyError as e:
    logging.error(f"KeyError exception occurred: {e}")

By following these best practices, you can effectively handle KeyError exceptions and provide a better user experience.