Tutorial

You will build an assistant in this tutorial for helping people transfer money. This tutorial does not assume any existing knowledge of Rasa or chatbots. The techniques you will learn in this tutorial are fundamental to building any Rasa assistant, and understanding it will bring you quite far along to mastering Rasa.

What are you building?#

In this tutorial, you will build an LLM-powered assistant that can complete a money transfer, reliably executing your business logic while allowing for fluid conversation.

Here are some of the conversations your assistant will be able to handle:

Following This Tutorial#

Whenever there is something for you to do, you'll see this label:

Prerequisites#

To follow this tutorial, you will need:

• a free Rasa Pro Developer Edition license
• an API key for OpenAI or another LLM provider

Setup#

For new users, the easiest way to get started is in the browser with a GitHub Codespace.

You can also install rasa-pro locally and use your own machine.

To code along with this tutorial, navigate to an empty directory in your terminal, and run:

By default, this tutorial uses the OpenAI API. If you'd like to use a different LLM, follow the instructions here.

If you're using a codespace, you already set your environment variables during setup. If you've installed Rasa Pro locally, set your OpenAI API key and Rasa Pro license in an environment variables:

Then replace your-api-key and your-rasa-pro-license-key with the actual keys.

Overview#

Open up the project folder in your IDE to see the files that make up your new project. In this tutorial you will primarily work with the following files:

• data/flows.yml
• domain.yml
• actions/actions.py

Testing your money transfer flow#

Train your assistant by running:

And start talking to it in the browser by running:

info

When you run the rasa inspect command in a GitHub Codespace, you'll see a notification that your application is available on port 5005. Click 'Open in Browser' to access the inspector and start chatting.

Now, try telling the assistant that you'd like to transfer some money to a friend.

Understanding your money transfer flow.#

The file data/flows.yml contains the definition of a flow called transfer_money. Let's look at this definition to see what is going on:

The two key attributes of the transfer_money flow are the description and the steps. The description is used to help decide when to activate this flow. But it is also helpful for anyone who inspects your code to understand what is going on. If a user says "I need to transfer some money", the description helps Rasa understand that this is the relevant flow. The steps describe the business logic required to do what the user asked for.

The first step in your flow is a collect step, which is used to fill a slot. A collect step sends a message to the user requesting information, and waits for an answer.

Collecting Information in Slots#

Slots are variables that your assistant can read and write throughout a conversation. Slots are defined in your domain.yml file. For example, the definition of your recipient slot looks like this:

Slots can be used to store information that users provide during the conversation, or information that has been fetched via an API call. First, you're going to see how to store information provided by the end user in a slot. To do this, you define a collect step like the first step in your flow above.

Rasa will look for a response called utter_ask_recipient in your domain file and use this to phrase the question to the user.

After sending this message, Rasa will wait for a response from the user. When the user responds, Rasa will try to use their answer to fill the slot recipient. Read about slot validation to learn how you can run extra checks on the slot values Rasa has extracted.

The diagram below summarizes how slot values are used to collect and store information, and how they can be used to create branching logic.

Descriptions in collect steps#

The second collect step includes a description of the information your assistant will request from the user. Descriptions are optional, but can help Rasa extract slot values more reliably.

Action Steps#

The third step in your transfer_money flow is not a collect step but an action step. When you reach an action step in a flow, your assistant will execute the corresponding action and then proceed to the next step. It will not stop to wait for the user's next message. For now, this is the final step in the flow, so there is no next step to execute and the flow completes.

Branching Logic#

Slots are also used to build branching logic in flows.

You're going to introduce an extra step to your flow, asking the user to confirm the amount and the recipient before sending the transfer. Since you are asking a yes/no question, you can store the result in a boolean slot which you will call final_confirmation.

In your domain file, add the definition of the final_confirmation slot and the corresponding response: utter_ask_final_confirmation. Also add a response to confirm the transfer has been cancelled.

Notice that your confirmation question uses curly brackets {} to include slot values in your response.

Add a collect step to your flow for the slot final_confirmation. This step includes a next attribute with your branching logic. The expression after the if key will be evaluated to true or false to determine the next step in your flow. The then and else keys can contain either a list of steps or the id of a step to jump to. In this case, the then key contains an action step to inform the user their transfer was cancelled. The else key contains the id transfer_successful. Notice that you've added this id to the final step in your flow.

To try out the updated version of your assistant, run rasa train, and then rasa inspect to talk to your assistant. It should now ask you to confirm before completing the transfer.

Integrating an API call#

An action step in a flow can describe two types of actions. If the name of the action starts with utter_, then this action sends a message to the user. The name of the action has to match the name of one of the responses defined in your domain. The final step in your flow contains the action utter_transfer_complete, and this response is also defined in your domain. Responses can contain buttons, images, and custom payloads. You can learn more about everything you can do with responses here.

The second type of action is a custom action. The name of a custom action starts with action_.

You are going to create a custom action, action_check_sufficient_funds, to check whether the user has enough money to make the transfer, and then add logic to your flow to handle both cases.

Your custom action is defined in the file actions/actions.py. To learn more about custom actions, go here.

Your actions.py file should look like this:

Slots are the primary way to pass information to and from custom actions. In the run() method above, you access the value of the amount slot that was set during the conversation, and you pass information back to the conversation by returning a SlotSet event to update the has_sufficient_funds slot.

Now you are going to make three additions to your domain.yml. You will add a top-level section listing your custom actions. You will add the new boolean slot has_sufficient_funds, and you will add a new response to send to the user in case they do not have sufficient funds.

Now you are going to update your flow logic to handle the cases where the user does or does not have enough money in their account to make the transfer.

Notice that your collect: final_confirmation step now also has an id so that your branching logic can jump to it.

Testing your Custom Action#

Double check that in the file endpoints.yml, that the section for your custom action server is uncommented:

In the terminal, stop and restart the inspector by running rasa inspect. When you reach the "check_funds" step in your flow, Rasa will call the custom action action_check_sufficient_funds. We have hardcoded the user's balance to be 1000, so if you try to send more, the assistant will tell you that you don't have enough funds in your account.

At this point you have experience using some of the key concepts involved in building with Rasa. Congratulations!