Prompt components in Langflow

A prompt is a structured input to a language model that instructs the model how to handle user inputs and variables.

Prompt components create prompt templates with custom fields and dynamic variables for providing your model structured, repeatable prompts.

Prompts are a combination of natural language and variables created with curly braces.

Use a prompt component in a flow

An example of modifying a prompt can be found in the Quickstart, where a basic chatbot flow is extended to include a full vector RAG pipeline.

The default prompt in the Prompt component is Answer the user as if you were a GenAI expert, enthusiastic about helping them get started building something fresh.

This prompt creates a "personality" for your LLM's chat interactions, but it doesn't include variables that you may find useful when templating prompts.

To modify the prompt template, in the Prompt component, click the Template field. For example, the {context} variable gives the LLM model access to embedded vector data to return better answers.

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Given the context

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{context}

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Answer the question

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{user_question}

When variables are added to a prompt template, new fields are automatically created in the component. These fields can be connected to receive text input from other components to automate prompting, or to output instructions to other components. An example of prompts controlling agents behavior is available in the sequential tasks agent starter flow.

Inputs

Name	Display Name	Info
template	Template	Create a prompt template with dynamic variables.

Outputs

Name	Display Name	Info
prompt	Prompt Message	The built prompt message returned by the build_prompt method.

Langchain Hub Prompt Template

This component fetches prompts from the Langchain Hub.

When a prompt is loaded, the component generates input fields for custom variables. For example, the default prompt "efriis/my-first-prompt" generates fields for profession and question.

Inputs

Name	Display Name	Info
langchain_api_key	Your LangChain API Key	The LangChain API Key to use.
langchain_hub_prompt	LangChain Hub Prompt	The LangChain Hub prompt to use.

Outputs

Name	Display Name	Info
prompt	Build Prompt	The built prompt message returned by the build_prompt method.