Input Variables Missing Error in ChatPromptTemplate Function

What will you learn?

In this comprehensive guide, you will delve into resolving the issue of missing input variables within the ChatPromptTemplate function. By understanding the expected order of variables and how to rectify this error, you will enhance your problem-solving skills in Python.

Introduction to the Problem and Solution

Encountering an error related to missing input variables is a common issue when utilizing the ChatPromptTemplate function. This error arises when the expected order of variables, namely [‘agent_scratchpad’, ‘input’], is not adhered to during function invocation.

To overcome this challenge effectively, it is crucial to ensure that the correct input variables are provided in the specified order when calling the ChatPromptTemplate function. By aligning with these requirements, you can prevent errors and optimize the functionality of your Python code.


# Ensure correct order of input variables: ['agent_scratchpad', 'input']
def ChatPromptTemplate(agent_scratchpad, user_input):
    # Your code logic here

# Correctly call ChatPromptTemplate with required arguments
response = ChatPromptTemplate(agent_scratchpad_value, user_input_value)  # Replace with actual values

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The provided code snippet illustrates defining a function ChatPromptTemplate that necessitates two input parameters – agent_scratchpad and user_input. It is essential to pass these inputs in the correct order during function invocation to avoid encountering missing variable errors.

  • Defining the Function: The function is structured with specific parameter names to align with its internal operations.
  • Calling the Function: When invoking ChatPromptTemplate, ensure both agent_scratchpad and user_input values are provided in sequence.

By following these guidelines and structuring your code accurately as demonstrated above, you can mitigate issues associated with missing input variables in Python functions like ChatPromptTemplate.

  1. How can I identify which variables are missing in a Python function?

  2. You can identify missing variables by referring to error messages or reviewing a function’s documentation for required parameters.

  3. Why is maintaining variable order significant when calling functions?

  4. Maintaining variable order ensures that each argument aligns correctly with its respective parameter during a function call.

  5. Can default arguments help avoid missing variable errors?

  6. Yes, specifying default values for certain arguments in a Python function definition makes them optional during invocation.

  7. Is there a tool available for automatically detecting missing inputs in functions?

  8. Linting tools such as pylint can aid in identifying potential issues like missing inputs while coding in Python.

  9. How can I handle cases where multiple functions require similar sets of input variables?

  10. Creating utility functions or dictionaries containing common inputs can streamline passing parameters across multiple functions efficiently.


Resolving errors stemming from missing input variables requires meticulous attention while defining and invoking Python functions. By adhering to prescribed naming conventions and consistently providing necessary arguments, you pave the way for smoother execution of code functionalities. Embrace best practices and maintain clarity within your custom functions through proper documentation using docstrings and type hints.

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