FewShotPromptWithTemplates Class — langchain Architecture

Architecture documentation for the FewShotPromptWithTemplates class in few_shot_with_templates.py from the langchain codebase.

Class python

Entity Profile

Dependency Diagram

graph TD
  713e8d01_f24d_0ae6_d363_33f3f321e867["FewShotPromptWithTemplates"]
  a3097815_cadb_7ebc_b29a_72117ccf6e27["StringPromptTemplate"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|extends| a3097815_cadb_7ebc_b29a_72117ccf6e27
  5b0211c9_fbcc_94a9_d100_7d26aec78d95["few_shot_with_templates.py"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|defined in| 5b0211c9_fbcc_94a9_d100_7d26aec78d95
  a3f0d1d5_bb71_f698_1648_c88741366b81["get_lc_namespace()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| a3f0d1d5_bb71_f698_1648_c88741366b81
  3ce04d7d_cb10_77fb_04d5_c0bbbb0e7bd0["check_examples_and_selector()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| 3ce04d7d_cb10_77fb_04d5_c0bbbb0e7bd0
  6351a5e0_1324_9ff2_cc0b_c6855751b691["template_is_valid()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| 6351a5e0_1324_9ff2_cc0b_c6855751b691
  cf752071_f46a_dd3b_3e62_5b429e8d1c30["_get_examples()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| cf752071_f46a_dd3b_3e62_5b429e8d1c30
  93fc120e_b1a5_fcae_169a_ef5b5f0fa7ea["_aget_examples()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| 93fc120e_b1a5_fcae_169a_ef5b5f0fa7ea
  e11fdc59_f61b_01d0_db98_f83ce25c7a66["format()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| e11fdc59_f61b_01d0_db98_f83ce25c7a66
  1be82c67_7cbe_640e_5a7c_6cbdd88cb446["aformat()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| 1be82c67_7cbe_640e_5a7c_6cbdd88cb446
  54e512c7_1cdb_8653_99d2_1aa95d495416["_prompt_type()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| 54e512c7_1cdb_8653_99d2_1aa95d495416
  e5717bb4_4164_ada5_65e0_50cbf5c4203e["save()"]
  713e8d01_f24d_0ae6_d363_33f3f321e867 -->|method| e5717bb4_4164_ada5_65e0_50cbf5c4203e

Relationship Graph

Source Code

libs/core/langchain_core/prompts/few_shot_with_templates.py lines 18–230

class FewShotPromptWithTemplates(StringPromptTemplate):
    """Prompt template that contains few shot examples."""

    examples: list[dict] | None = None
    """Examples to format into the prompt.

    Either this or `example_selector` should be provided.
    """

    example_selector: BaseExampleSelector | None = None
    """`ExampleSelector` to choose the examples to format into the prompt.

    Either this or `examples` should be provided.
    """

    example_prompt: PromptTemplate
    """`PromptTemplate` used to format an individual example."""

    suffix: StringPromptTemplate
    """A `PromptTemplate` to put after the examples."""

    example_separator: str = "\n\n"
    """String separator used to join the prefix, the examples, and suffix."""

    prefix: StringPromptTemplate | None = None
    """A `PromptTemplate` to put before the examples."""

    template_format: PromptTemplateFormat = "f-string"
    """The format of the prompt template.

    Options are: `'f-string'`, `'jinja2'`, `'mustache'`.
    """

    validate_template: bool = False
    """Whether or not to try validating the template."""

    @classmethod
    def get_lc_namespace(cls) -> list[str]:
        """Get the namespace of the LangChain object.

        Returns:
            `["langchain", "prompts", "few_shot_with_templates"]`
        """
        return ["langchain", "prompts", "few_shot_with_templates"]

    @model_validator(mode="before")
    @classmethod
    def check_examples_and_selector(cls, values: dict) -> Any:
        """Check that one and only one of examples/example_selector are provided."""
        examples = values.get("examples")
        example_selector = values.get("example_selector")
        if examples and example_selector:
            msg = "Only one of 'examples' and 'example_selector' should be provided"
            raise ValueError(msg)

        if examples is None and example_selector is None:
            msg = "One of 'examples' and 'example_selector' should be provided"
            raise ValueError(msg)

        return values

    @model_validator(mode="after")
    def template_is_valid(self) -> Self:
        """Check that prefix, suffix, and input variables are consistent."""
        if self.validate_template:
            input_variables = self.input_variables
            expected_input_variables = set(self.suffix.input_variables)
            expected_input_variables |= set(self.partial_variables)
            if self.prefix is not None:
                expected_input_variables |= set(self.prefix.input_variables)
            missing_vars = expected_input_variables.difference(input_variables)
            if missing_vars:
                msg = (
                    f"Got input_variables={input_variables}, but based on "
                    f"prefix/suffix expected {expected_input_variables}"
                )
                raise ValueError(msg)
        else:
            self.input_variables = sorted(
                set(self.suffix.input_variables)
                | set(self.prefix.input_variables if self.prefix else [])