These docs are for version 1.x of Rasa Open Source.

## Rasa SDK

Rasa SDK provides the tools you need to write custom actions in python.

### Installation

Use `pip` to install `rasa-sdk` on your action server.

```
pip install rasa-sdk
```

Note

You do not need to install `rasa` for your action server. E.g. if you are running Rasa in a docker container, it is recommended to create a separate container for your action server. In this separate container, you only need to install `rasa-sdk`.

### Running the Action Server

If you have `rasa` installed, run this command to start your action server:

```
rasa run actions
```

Otherwise, if you do not have `rasa` installed, run this command:

```
python -m rasa_sdk --actions actions
```

You can verify that the action server is up and running with the command:

```
curl http://localhost:5055/health
```

You can get the list of registered custom actions with the command:

```
curl http://localhost:5055/actions
```

### Actions

The `Action` class is the base class for any custom action. It has two methods that both need to be overwritten, `name()` and `run()`.

In a restaurant bot, if the user says “show me a Mexican restaurant”, your bot could execute the action `ActionCheckRestaurants`:

```
from rasa_sdk import Action
from rasa_sdk.events import SlotSet

class ActionCheckRestaurants(Action):
   def name(self) -> Text:
      return "action_check_restaurants"

def run(self,
           dispatcher: CollectingDispatcher,
           tracker: Tracker,
           domain: Dict[Text, Any]) -> List[Dict[Text, Any]]:

cuisine = tracker.get_slot('cuisine')
      q = "select * from restaurants where cuisine='{0}' limit 1".format(cuisine)
      result = db.query(q)

return [SlotSet("matches", result if result is not None else [])]
```

### Customizing the session start action

The default behavior of the session start action is to take all existing slots and to carry them over into the next session. Let’s say you do not want to carry over all slots, but only a user’s name and their phone number. To do that, you’d override the `action_session_start` with a custom action:

```
from typing import Text, List, Dict, Any

from rasa_sdk import Action, Tracker
from rasa_sdk.events import SlotSet, SessionStarted, ActionExecuted, EventType
from rasa_sdk.executor import CollectingDispatcher

class ActionSessionStart(Action):
    def name(self) -> Text:
        return "action_session_start"

@staticmethod
    def fetch_slots(tracker: Tracker) -> List[EventType]:
        slots = []

for key in ("name", "phone_number"):
            value = tracker.get_slot(key)
            if value is not None:
                slots.append(SlotSet(key=key, value=value))

return slots

async def run(
        self,
        dispatcher: CollectingDispatcher,
        tracker: Tracker,
        domain: Dict[Text, Any],
    ) -> List[EventType]:

events = [SessionStarted()]
        events.extend(self.fetch_slots(tracker))
        events.append(ActionExecuted("action_listen"))

return events
```

### Events

An action’s `run()` method returns a list of events. If the action should not trigger any other events, it should return an empty list.

### Tracker

The `rasa_sdk.Tracker` lets you access the bot’s memory in your custom actions. You can get information about past events and the current state of the conversation through `Tracker` attributes and methods.

The following are available as attributes of a `Tracker` object:

- `sender_id` - The unique ID of person talking to the bot.
- `slots` - The list of slots that can be filled as defined in the domains.
- `latest_message` - A dictionary containing the attributes of the latest message: `intent`, `entities` and `text`.
- `events` - A list of all previous events.
- `active_form` - The name of the currently active form.
- `latest_action_name` - The name of the last action the bot executed.