_StringImageMessagePromptTemplate Class — langchain Architecture

Source Code

libs/core/langchain_core/prompts/chat.py lines 396–660

class _StringImageMessagePromptTemplate(BaseMessagePromptTemplate):
    """Human message prompt template. This is a message sent from the user."""

    prompt: (
        StringPromptTemplate
        | list[StringPromptTemplate | ImagePromptTemplate | DictPromptTemplate]
    )
    """Prompt template."""
    additional_kwargs: dict = Field(default_factory=dict)
    """Additional keyword arguments to pass to the prompt template."""

    _msg_class: type[BaseMessage]

    @classmethod
    def from_template(
        cls: type[Self],
        template: str
        | list[str | _TextTemplateParam | _ImageTemplateParam | dict[str, Any]],
        template_format: PromptTemplateFormat = "f-string",
        *,
        partial_variables: dict[str, Any] | None = None,
        **kwargs: Any,
    ) -> Self:
        """Create a class from a string template.

        Args:
            template: a template.
            template_format: format of the template.

                Options are: `'f-string'`, `'mustache'`, `'jinja2'`.
            partial_variables: A dictionary of variables that can be used too partially.

            **kwargs: Keyword arguments to pass to the constructor.

        Returns:
            A new instance of this class.

        Raises:
            ValueError: If the template is not a string or list of strings.
        """
        if isinstance(template, str):
            prompt: StringPromptTemplate | list = PromptTemplate.from_template(
                template,
                template_format=template_format,
                partial_variables=partial_variables,
            )
            return cls(prompt=prompt, **kwargs)
        if isinstance(template, list):
            if (partial_variables is not None) and len(partial_variables) > 0:
                msg = "Partial variables are not supported for list of templates."
                raise ValueError(msg)
            prompt = []
            for tmpl in template:
                if isinstance(tmpl, str) or (
                    isinstance(tmpl, dict)
                    and "text" in tmpl
                    and set(tmpl.keys()) <= {"type", "text"}
                ):
                    if isinstance(tmpl, str):
                        text: str = tmpl
                    else:
                        text = cast("_TextTemplateParam", tmpl)["text"]  # type: ignore[assignment]
                    prompt.append(
                        PromptTemplate.from_template(
                            text, template_format=template_format
                        )
                    )
                elif (
                    isinstance(tmpl, dict)
                    and "image_url" in tmpl
                    and set(tmpl.keys())
                    <= {
                        "type",
                        "image_url",
                    }
                ):
                    img_template = cast("_ImageTemplateParam", tmpl)["image_url"]
                    input_variables = []
                    if isinstance(img_template, str):
                        variables = get_template_variables(
                            img_template, template_format