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fix: Revert back to straightforward PromptBuilder (#6335)
* Revert back to simple PromptBuilder * Updating to full typing
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haystack/preview/components/builders/prompt_builder.py
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,140 +1,41 @@ | ||
| from typing import Dict, Any, Optional, List | ||
| from typing import Dict, Any | ||
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| from jinja2 import Template, meta | ||
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| from haystack.preview import component | ||
| from haystack.preview import default_to_dict | ||
| from haystack.preview.dataclasses.chat_message import ChatMessage, ChatRole | ||
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| @component | ||
| class PromptBuilder: | ||
| """ | ||
| A component for building prompts using template strings or template variables. | ||
| The `PromptBuilder` can be initialized with a template string or template variables to dynamically build | ||
| a prompt. There are two distinct use cases: | ||
| 1. **Static Template**: When initialized with a `template` string, the `PromptBuilder` will always use | ||
| this template for rendering prompts throughout its lifetime. | ||
| 2. **Dynamic Templates**: When initialized with `template_variables` and receiving messages in | ||
| `ChatMessage` format, it allows for different templates for each message, enabling prompt templating | ||
| on a per-user message basis. | ||
| :param template: (Optional) A template string to be rendered using Jinja2 syntax, e.g., | ||
| "What's the weather like in {{ location }}?". This template will be used for all | ||
| prompts. Defaults to None. | ||
| :param template_variables: (Optional) A list of all template variables to be used as input. | ||
| This parameter enables dynamic templating based on user messages. Defaults to None. | ||
| :raises ValueError: If neither `template` nor `template_variables` are provided. | ||
| Usage (static templating): | ||
| PromptBuilder is a component that renders a prompt from a template string using Jinja2 engine. | ||
| The template variables found in the template string are used as input types for the component and are all required. | ||
| Usage: | ||
| ```python | ||
| template = "Translate the following context to {{ target_language }}. Context: {{ snippet }}; Translation:" | ||
| builder = PromptBuilder(template=template) | ||
| builder.run(target_language="spanish", snippet="I can't speak spanish.") | ||
| ``` | ||
| The above template is used for all messages that are passed to the `PromptBuilder`. | ||
| Usage (dynamic templating): | ||
| ```python | ||
| from haystack.preview.dataclasses.chat_message import ChatMessage | ||
| template = "What's the weather like in {{ location }}?" | ||
| prompt_builder = PromptBuilder(template_variables=["location", "time"]) | ||
| messages = [ChatMessage.from_system("Always start response to user with Herr Blagojevic. | ||
| Respond in German even if some input data is in other languages"), | ||
| ChatMessage.from_user(template)] | ||
| response = pipe.run(data={"prompt_builder": {"location": location, "messages": messages}}) | ||
| ``` | ||
| In this example, only the last user message is templated. The template_variables parameter in the PromptBuilder | ||
| initialization specifies all potential template variables, yet only the variables utilized in the template are | ||
| required in the run method. For instance, since the time variable isn't used in the template, it's not | ||
| necessary in the run method invocation above. | ||
| Note: | ||
| The behavior of `PromptBuilder` is determined by the initialization parameters. A static template | ||
| provides a consistent prompt structure, while template variables offer dynamic templating per user | ||
| message. | ||
| """ | ||
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| def __init__(self, template: Optional[str] = None, template_variables: Optional[List[str]] = None): | ||
| def __init__(self, template: str): | ||
| """ | ||
| Initialize the component with either a template string or template variables. | ||
| If template is given PromptBuilder will parse the template string and use the template variables | ||
| as input types. Conversely, if template_variables are given, PromptBuilder will directly use | ||
| them as input variables. | ||
| If neither template nor template_variables are provided, an error will be raised. If both are provided, | ||
| an error will be raised as well. | ||
| Initialize the component with a template string. | ||
| :param template: Template string to be rendered. | ||
| :param template_variables: List of template variables to be used as input types. | ||
| :param template: Jinja2 template string, e.g. "Summarize this document: {documents}\nSummary:" | ||
| :type template: str | ||
| """ | ||
| if template_variables and template: | ||
| raise ValueError("template and template_variables cannot be provided at the same time.") | ||
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| # dynamic per-user message templating | ||
| if template_variables: | ||
| # treat vars as optional input slots | ||
| dynamic_input_slots = {var: Optional[Any] for var in template_variables} | ||
| self.template = None | ||
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| # static templating | ||
| else: | ||
| if not template: | ||
| raise ValueError("Either template or template_variables must be provided.") | ||
| self.template = Template(template) | ||
| ast = self.template.environment.parse(template) | ||
| static_template_variables = meta.find_undeclared_variables(ast) | ||
| # treat vars as required input slots - as per design | ||
| dynamic_input_slots = {var: Any for var in static_template_variables} | ||
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| # always provide all serialized vars, so we can serialize | ||
| # the component regardless of the initialization method (static vs. dynamic) | ||
| self.template_variables = template_variables | ||
| self._template_string = template | ||
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| optional_input_slots = {"messages": Optional[List[ChatMessage]]} | ||
| component.set_input_types(self, **optional_input_slots, **dynamic_input_slots) | ||
| self.template = Template(template) | ||
| ast = self.template.environment.parse(template) | ||
| template_variables = meta.find_undeclared_variables(ast) | ||
| component.set_input_types(self, **{var: Any for var in template_variables}) | ||
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| def to_dict(self) -> Dict[str, Any]: | ||
| return default_to_dict(self, template=self._template_string, template_variables=self.template_variables) | ||
| return default_to_dict(self, template=self._template_string) | ||
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| @component.output_types(prompt=str) | ||
| def run(self, messages: Optional[List[ChatMessage]] = None, **kwargs): | ||
| """ | ||
| Build and return the prompt based on the provided messages and template or template variables. | ||
| If `messages` are provided, the template will be applied to the last user message. | ||
| :param messages: (Optional) List of `ChatMessage` instances, used for dynamic templating | ||
| when `template_variables` are provided. | ||
| :param kwargs: Additional keyword arguments representing template variables. | ||
| """ | ||
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| if messages: | ||
| # apply the template to the last user message only | ||
| last_message: ChatMessage = messages[-1] | ||
| if last_message.is_from(ChatRole.USER): | ||
| template = Template(last_message.content) | ||
| return {"prompt": messages[:-1] + [ChatMessage.from_user(template.render(kwargs))]} | ||
| else: | ||
| return {"prompt": messages} | ||
| else: | ||
| if self.template: | ||
| return {"prompt": self.template.render(kwargs)} | ||
| else: | ||
| raise ValueError( | ||
| "PromptBuilder was initialized with template_variables, but no ChatMessage(s) were provided." | ||
| ) | ||
| def run(self, **kwargs): | ||
| return {"prompt": self.template.render(kwargs)} |
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