Variables and dynamic content in LangChain - Mini Project: Build & Apply

Variables and Dynamic Content in LangChain

📖 Scenario: You are building a simple chatbot using LangChain that can greet users by their name and respond dynamically based on the input.

🎯 Goal: Create a LangChain chatbot that uses variables to store user input and dynamically generates a greeting message.

📋 What You'll Learn

Create a variable to hold the user's name

Set up a prompt template that uses the variable

Use LangChain's PromptTemplate to inject the variable dynamically

Generate the final prompt with the user's name included

💡 Why This Matters

🌍 Real World

Chatbots and AI assistants often need to personalize messages using variables like user names or preferences.

💼 Career

Understanding how to use variables and dynamic content in LangChain is essential for building flexible and interactive AI applications.

1

Create a variable for the user's name

Create a variable called user_name and set it to the string "Alice".

LangChain

# Your code here

Need a hint?

Use simple assignment to store the name.

2

Set up a prompt template with a variable placeholder

Create a string variable called template with the value "Hello, {name}! Welcome to LangChain.".

LangChain

user_name = "Alice"
template = ""  # Your code here

Need a hint?

Use curly braces {name} to mark where the variable will go.

3

Create a PromptTemplate using LangChain

Import PromptTemplate from langchain.prompts and create a PromptTemplate instance called prompt using the template string and the input variable name.

LangChain

user_name = "Alice"
template = "Hello, {name}! Welcome to LangChain."
# Your code here

Need a hint?

Use PromptTemplate(template=template, input_variables=["name"]) to create the prompt.

4

Generate the final prompt with the user's name

Use the prompt.format method with the argument name=user_name and assign the result to a variable called final_prompt.

LangChain

from langchain.prompts import PromptTemplate

user_name = "Alice"
template = "Hello, {name}! Welcome to LangChain."
prompt = PromptTemplate(template=template, input_variables=["name"])
# Your code here

Need a hint?

Call prompt.format(name=user_name) to replace the variable in the template.