Using Templates In Chains

Introduction

Templates are a powerful feature in LangChain that allow you to create dynamic and reusable content. By using templates, you can define a structure with placeholders that can be replaced with actual values at runtime. This tutorial will guide you through the process of using templates in chains from start to finish.

What are Templates in LangChain?

Templates in LangChain are predefined structures that include placeholders for dynamic content. These placeholders can be replaced with actual values when the template is executed. This allows for the creation of flexible and reusable components that can adapt to different inputs.

Creating a Template

To create a template, you define a string with placeholders enclosed in curly braces. For example:


                    template_string = "Hello, {name}! Welcome to {platform}."

In this template, {name} and {platform} are placeholders that will be replaced with actual values when the template is executed.

To use a template in a chain, you need to follow these steps:

Create a template string with placeholders.
Define a function that will replace the placeholders with actual values.
Execute the template with the provided values.

Let's go through each step with an example.

Step 1: Create a Template String

First, create a template string with placeholders:


                    template_string = "Hello, {name}! Welcome to {platform}."

Step 2: Define a Function to Replace Placeholders

Next, define a function that takes a dictionary of values and replaces the placeholders in the template with the actual values:


                    def apply_template(template, values):
                        return template.format(**values)

Step 3: Execute the Template

Finally, execute the template with the provided values:


                    values = {"name": "Alice", "platform": "LangChain"}
                    result = apply_template(template_string, values)
                    print(result)

The output will be:

Hello, Alice! Welcome to LangChain.

Advanced Usage

You can also use templates for more complex scenarios, such as looping through a list of items or conditional content. Here is an example of a more advanced template:


                    template_string = "Hello, {name}! You have the following tasks:\n{tasks}"
                    
                    def format_tasks(tasks):
                        return "\n".join(f"- {task}" for task in tasks)
                    
                    def apply_template(template, values):
                        values['tasks'] = format_tasks(values['tasks'])
                        return template.format(**values)
                    
                    values = {
                        "name": "Alice",
                        "tasks": ["Task 1", "Task 2", "Task 3"]
                    }
                    result = apply_template(template_string, values)
                    print(result)

The output will be:

Hello, Alice! You have the following tasks:
- Task 1
- Task 2
- Task 3

Conclusion

Using templates in LangChain allows you to create flexible and reusable content that can adapt to different inputs. By following the steps outlined in this tutorial, you can create and use templates effectively in your chains. Experiment with different scenarios and advanced features to fully leverage the power of templates in LangChain.

Using Templates in Chains - LangChain Tutorial

Introduction

What are Templates in LangChain?

Creating a Template