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Prompt Template

Use the Prompt Template core component to create a prompt that supplies instructions and context to an LLM or agent, separate from other input like chat messages and file uploads.

Prompts are structured input that use natural language, fixed values, and dynamic variables to provide baseline context for the LLM. For example:

  • Define a consistent structure for user queries, making it easier for the LLM to understand and respond appropriately.
  • Define a specific output format for the LLM, such as JSON or structured text.
  • Define a role for the LLM, such as You are a helpful assistant or You are an expert in microbiology.
  • Allow the LLM to reference chat memory.

The Prompt Template component can also output variable instructions to other components later in the flow.

Prompt Template parameters​

NameDisplay NameDescription
templateTemplateInput parameter. Create a prompt template with dynamic variables ({VARIABLE_NAME}).
promptPrompt MessageOutput parameter. The built prompt message returned by the build_prompt method.

Define variables in prompts​

Variables in a Prompt Template component dynamically add fields to the Prompt Template component so that your flow can receive definitions for those values from other components, Langflow global variables, or fixed input.

For example, with the Message History component, you can use a {memory} variable to pass chat history to the prompt.

The following steps demonstrate how to add variables to a Prompt Template component:

  1. Create a flow based on the Basic prompting template.

    This template already has a Prompt Template component, but the template only contains natural language instructions: Answer the user as if you were a GenAI expert, enthusiastic about helping them get started building something fresh.

    This prompt defines a role for the LLM's chat interactions, but it doesn't include variables that help you create prompts that adapt dynamically to changing contexts, such as different users and environments.

  2. Click the Prompt Template component, and then add some variables to the Template field.

    Variables are declared by wrapping the variable name in curly braces, like {variable_name}. For example, the following template creates context and user_question variables:


    _10
    Given the context
    _10
    {context}
    _10
    Answer the question
    _10
    {user_question}

  3. Click Check & Save to save the template.

    After adding the variables to the template, new fields are added to the Prompt Template component for each variable.

  4. Provide input for the variable fields:

    • Connect the fields to other components to pass the output from those components to the variables.
    • Use Langflow global variables.
    • Enter fixed values directly into the fields.

See also​

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