Rasa Tutorial

This page explains the basics of building an assistant with Rasa and shows the structure of a Rasa project.

You will build a simple, friendly assistant which will ask how you’re doing and send you a fun picture to cheer you up if you are sad.


1. Create a New Project

The first step is to create a new Rasa project. To do this, run:

rasa init --no-prompt

The rasa init command creates all the files that a Rasa project needs. If you leave out the --no-prompt flag you will be asked some questions about how you want your project to be set up.

This creates the following files:

__init__.py an empty file that helps python find your actions
actions.py code for your custom actions
config.yml ‘*’ configuration of your NLU and Core models
credentials.yml details for connecting to other services
data/nlu.md ‘*’ your NLU training data
data/stories.md ‘*’ your stories
domain.yml ‘*’ your assistant’s domain
endpoints.yml details for connecting to channels like fb messenger
models/<timestamp>.tar.gz your initial model

The most important files are marked with a ‘*’. You will learn about all of these in this tutorial.

To check that all the files were created, run:

ls -1

2. Create NLU Examples

The first piece of a Rasa assistant is an NLU model. NLU stands for Natural Language Understanding, which means turning user messages into structured data. To do this with Rasa, you provide training examples that show how Rasa should understand user messages, and then train a model by showing it those examples.

Run the code cell below to see the NLU training data created by the rasa init command:

cat data/nlu.md

The lines starting with ## define the names of your intents, which are groups of messages with the same meaning. Rasa’s job will be to predict the correct intent when your users send new, unseen messages to your assistant. You can find all the details of the data format in Training Data Format.

3. Define Your Model Configuration

The configuration file defines the NLU and Core components that your model will use. In this example, your NLU model will use the supervised_embeddings pipeline. You can learn about the different NLU pipelines here.

Let’s take a look at your model configuration file.

cat config.yml

The pipeline and language keys specify how the NLU model should be built. The policies key defines the policies that the Core model will use.

4. Write Your First Stories

At this stage, you will teach your assistant how to respond to your messages. This is called dialogue management, and is handled by your Core model.

Core models learn from real conversational data in the form of training “stories”. A story is a real conversation between a user and an assistant. Lines with intents and entities reflect the user’s input and action names show what the assistant should do in response.

Below is an example of a simple conversation. The user says hello, and the assistant says hello back. This is how it looks as a story:

## story1
* greet
   - utter_greet

You can see the full details in Stories.

Lines that start with - are actions taken by the assistant. In this tutorial, all of our actions are messages sent back to the user, like utter_greet, but in general, an action can do anything, including calling an API and interacting with the outside world.

Run the command below to view the example stories inside the file data/stories.md:

cat data/stories.md

5. Define a Domain

The next thing we need to do is define a Domain. The domain defines the universe your assistant lives in - what user inputs it should expect to get, what actions it should be able to predict, how to respond, and what information to store. The domain for our assistant is saved in a file called domain.yml:

cat domain.yml

So what do the different parts mean?

intents things you expect users to say
actions things your assistant can do and say
templates template strings for the things your assistant can say

How does this fit together? Rasa Core’s job is to choose the right action to execute at each step of the conversation. In this case, our actions simply send a message to the user. These simple utterance actions are the actions in the domain that start with utter_. The assistant will respond with a message based on a template from the templates section. See Custom Actions to build actions that do more than just send a message.

6. Train a Model

The next step is to train a neural network on our example stories and NLU data. To do this, run the command below. This command will call the Rasa Core and NLU train functions and store the trained model into the models/ directory. The output of this command will include the training results for each training epoch.

rasa train

echo "Finished training."

The rasa train command will look for both NLU and Core data and will train a combined model.

7. Talk to Your Assistant

Congratulations! 🚀 You just built an assistant powered entirely by machine learning.

The next step is to try it out! Start talking to your assistant by running:

rasa shell

You can also use Rasa X to collect more conversations and improve your assistant: