[Feature] Get actual formatted prompt

[JBExcoffier]

What feature would you like to see?

How could we access the actual and formatted prompt used by DSPy ?

I am using dspy python package with 2.6.15 version.

For-example, with the following :

class AnswerToQuestion(dspy.Signature):
    """
    Answer the question.
    """

    question: str = dspy.InputField(desc="Question")
    answer: str = dspy.OutputField(desc="Answer")

How could I get that the actual and formated prompt used by DSPy in the Predict (dspy.Predict(AnswerToQuestion)) is something like :

{'role': 'system', 'content': 'Your input fields are:\n1. question(str): Question\n\nYour output fields are:\n1.answer (str): Answer\n\nAll interactions will be structured in the following way, with the appropriate values filled in.\n\nInputs will have the following structure:\n\n[[ ## question ## ]]\n{question}\n\nOutputs will be a JSON object with the following fields.\n\n{\n "answer": "{answer}"\n}\n\nIn adhering to this structure, your objective is: \n Answer the question.'}

And this is incomplete since there is no the {'role': 'system', 'content': 'My actual question ?' with my actual question.

I need it since I want to be able to use the generated prompt externally(so not by the DSPy Predict function alone), for example for benchmarking purpose.

Is this already implemented ? Or does this need to be added ?

Thanks !

Would you like to contribute?

• Yes, I'd like to help implement this.
• No, I just want to request it.

Additional Context

No response

[marwood-p]

@JBExcoffier Have you tried using ChatAdapter.format() for this?

[JBExcoffier]

To get only the supposed system prompt I am using dspy.adapters.chat_adapter.prepare_instructions(signature=AnswerToQuestion).

But it only gives the following string :

Your input fields are:
1. `question` (str): Question

Your output fields are:
1. `answer` (str): Answer

All interactions will be structured in the following way, with the appropriate values filled in.

[[ ## question ## ]]
{question}

[[ ## answer ## ]]
{answer}

[[ ## completed ## ]]

In adhering to this structure, your objective is: 
        Answer the question.

For now I cannot access the actual messages that are sent to the language model, so encapsulated in a list with dict such as {'role':'system', 'content':above}.

Indeed dspy.ChatAdapter.format should give the above prompt well encapsulated in a OpenAI like list-dict format, but I cannot make it really work.

I don't want to pass few_shot examples so demos is an empty list. And with the following call :

dspy.ChatAdapter.format(
    signature=AnswerToQuestion, demos=[], inputs=[dict(question="Capital of the UK ?")]
)

It raises the following error : TypeError: ChatAdapter.format() missing 1 required positional argument: 'instance'

What's the correct way to pass the inputs please ? I already have the main part of the prompt with dspy.adapters.chat_adapter.prepare_instructions function (and it's no complete, e.g. the JSON part is not present), but if possible, I would like to have the full messages (including roles) as a template (without passing an actual input).

Thanks !

[marwood-p]

I'll let an author reply but I think this is what you want? It includes the full messages including the roles as an OpenAI-like list-dict. demos is []. It doesn't pass in an actual input.

import dspy

chat_adapter = dspy.ChatAdapter()
sig = dspy.ensure_signature('question -> answer')
messages = chat_adapter.format(sig, [], {})
print(messages)

[{'role': 'system', 'content': 'Your input fields are:\n1. `question` (str)\nYour output fields are:\n1. `answer` (str)\nAll interactions will be structured in the following way, with the appropriate values filled in.\n\n[[ ## question ## ]]\n{question}\n\n[[ ## answer ## ]]\n{answer}\n\n[[ ## completed ## ]]\nIn adhering to this structure, your objective is: \n        Given the fields `question`, produce the fields `answer`.'}, {'role': 'user', 'content': 'Respond with the corresponding output fields, starting with the field `[[ ## answer ## ]]`, and then ending with the marker for `[[ ## completed ## ]]`.'}]

Looking at your code, you may be confused about the difference between a ChatAdapter instance (which I use) and a ChatAdapter class (which you use). In case that help clarify why you got an error.

[JBExcoffier]

Indeed, it is better when I use the class.

With the following :

dspy.ChatAdapter().format(
    signature=AnswerToQuestion, demos=[], inputs=dict(question="[MY QUESTION]")
)

I get the following answer :

[{'role': 'system',
  'content': 'Your input fields are:\n1. `question` (str): Question\n\nYour output fields are:\n1. `answer` (str): Answer\n\nAll interactions will be structured in the following way, with the appropriate values filled in.\n\n[[ ## question ## ]]\n{question}\n\n[[ ## answer ## ]]\n{answer}\n\n[[ ## completed ## ]]\n\nIn adhering to this structure, your objective is: \n        Answer the question.'},
 {'role': 'user',
  'content': '[[ ## question ## ]]\n[MY QUESTION]\n\nRespond with the corresponding output fields, starting with the field `[[ ## answer ## ]]`, and then ending with the marker for `[[ ## completed ## ]]`.'}]

So it's fine ! But still not an actual template since I passed an input. Without the input (empty dict) I have an error, which is the same error I get when running your code : ValueError: Expected dict_keys(['question']) but got dict_keys([]).

Is am using DSPy 2.6.15 so maybe it's my version. Is it possible to get a full template answer (empty input) ? Thanks

[chenmoneygithub]

@JBExcoffier Thanks for reporting the issue!

The formatted prompt is actually a multi-turn message, to get that you can use dspy.inspect_history(), or dspy.settings.lm.history[-1]["messages"] to fetch it in your program.

If you want to see a more detailed breakdown of what's happening behind the scene, please try out MLflow tracing which visualizes every step: https://dspy.ai/tutorials/observability/