jinja2_formatter() — langchain Function Reference

Architecture documentation for the jinja2_formatter() function in string.py from the langchain codebase.

Function python PromptManagement ExampleSelection calls 1 called by 1

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PromptManagement→ ExampleSelection→ jinja2_formatter() — langchain Function Reference

Dependency Diagram

graph TD
  43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e["jinja2_formatter()"]
  a7a9f16f_a913_8e85_a792_d083dd92c428["string.py"]
  43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e -->|defined in| a7a9f16f_a913_8e85_a792_d083dd92c428
  43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e["jinja2_formatter()"]
  43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e -->|calls| 43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e
  43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e["jinja2_formatter()"]
  43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e -->|calls| 43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e
  style 43cc29b7_e3fc_e3fc_42e0_3e366fa58a5e fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/prompts/string.py lines 33–70

def jinja2_formatter(template: str, /, **kwargs: Any) -> str:
    """Format a template using jinja2.

    !!! warning "Security"

        As of LangChain 0.0.329, this method uses Jinja2's `SandboxedEnvironment` by
        default. However, this sandboxing should be treated as a best-effort approach
        rather than a guarantee of security.

        Do not accept jinja2 templates from untrusted sources as they may lead
        to arbitrary Python code execution.

        [More information.](https://jinja.palletsprojects.com/en/3.1.x/sandbox/)

    Args:
        template: The template string.
        **kwargs: The variables to format the template with.

    Returns:
        The formatted string.

    Raises:
        ImportError: If jinja2 is not installed.
    """
    if not _HAS_JINJA2:
        msg = (
            "jinja2 not installed, which is needed to use the jinja2_formatter. "
            "Please install it with `pip install jinja2`."
            "Please be cautious when using jinja2 templates. "
            "Do not expand jinja2 templates using unverified or user-controlled "
            "inputs as that can result in arbitrary Python code execution."
        )
        raise ImportError(msg)

    # Use a restricted sandbox that blocks ALL attribute/method access
    # Only simple variable lookups like {{variable}} are allowed
    # Attribute access like {{variable.attr}} or {{variable.method()}} is blocked
    return SandboxedEnvironment().from_string(template).render(**kwargs)