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

# Slots

## What are slots?
**Slots are your bot’s memory.** They act as a key-value store which can be used to store information the user provided (e.g their home city) as well as information gathered about the outside world (e.g. the result of a database query).

Most of the time, you want slots to influence how the dialogue progresses. There are different slot types for different behaviors.

For example, if your user has provided their home city, you might have a `text` slot called `home_city`. If the user asks for the weather, and you _don’t_ know their home city, you will have to ask them for it. A `text` slot only tells Rasa Core whether the slot has a value. The specific value of a `text` slot (e.g. Bangalore or New York or Hong Kong) doesn’t make any difference.

If the value itself is important, use a `categorical` or a `bool` slot. There are also `float`, and `list` slots. If you just want to store some data, but don’t want it to affect the flow of the conversation, use an `unfeaturized` slot.

## How Rasa Uses Slots
The `Policy` doesn’t have access to the value of your slots. It receives a featurized representation. As mentioned above, for a `text` slot the value is irrelevant.

**You should choose your slot types carefully!**

## How Slots Get Set
You can provide an initial value for a slot in your domain file:

```
slots:
  name:
    type: text
    initial_value: "human"
```

You can get the value of a slot using `.get_slot()` inside `actions.py` for example:

```
data = tracker.get_slot("slot-name")
```

There are multiple ways that slots are set during a conversation:

### Slots Set from NLU
If your NLU model picks up an entity, and your domain contains a slot with the same name, the slot will be set automatically. For example:

```
# story_01
* greet{"name": "Ali"}
  - slot{"name": "Ali"}
  - utter_greet
```

To disable this behavior for a particular slot, you can set the `auto_fill` attribute to `False` in the domain file:

```
slots:
  name:
    type: text
    auto_fill: False
```

### Slots Set By Clicking Buttons
You can use buttons as a shortcut. Rasa Core will send messages starting with a `/` to the `RegexInterpreter`, which expects NLU input in the same format as in story files, e.g. `/intent{entities}`. For example, if you let users choose a color by clicking a button, the button payloads might be `/choose{"color": "blue"}` and `/choose{"color": "red"}`.

You can specify this in your domain file like this:

```
utter_ask_color:
- text: "what color would you like?"
  buttons:
  - title: "blue"
    payload: '/choose{"color": "blue"}'
  - title: "red"
    payload: '/choose{"color": "red"}'
```

### Slots Set by Actions
The second option is to set slots by returning events in [custom actions](https://legacy-docs-v1.rasa.com/1.10.18/core/actions/#custom-actions). In this case, your stories need to include the slots. For example, you have a custom action to fetch a user’s profile, and you have a `categorical` slot called `account_type`.

When the `fetch_profile` action is run, it returns a [`rasa.core.events.SlotSet`](https://legacy-docs-v1.rasa.com/1.10.18/api/events/#rasa.core.events.SlotSet) event:

```
slots:
   account_type:
      type: categorical
      values:
      - premium
      - basic
```

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

class FetchProfileAction(Action):
    def name(self):
        return "fetch_profile"

def run(self, dispatcher, tracker, domain):
        url = "http://myprofileurl.com"
        data = requests.get(url).json
        return [SlotSet("account_type", data["account_type"])]
```

```
# story_01
* greet
  - action_fetch_profile
  - slot{"account_type" : "premium"}
  - utter_welcome_premium

# story_02
* greet
  - action_fetch_profile
  - slot{"account_type" : "basic"}
  - utter_welcome_basic
```

In this case you **do** have to include the `- slot{}` part in your stories. Rasa Core will learn to use this information to decide on the correct action to take (in this case, `utter_welcome_premium` or `utter_welcome_basic`).

Note
It is **very easy** to forget about slots if you are writing stories by hand. We strongly recommend that you build up these stories using [Interactive Learning with Forms](https://legacy-docs-v1.rasa.com/1.10.18/core/interactive-learning/#section-interactive-learning-forms) rather than writing them.

## Slot Types
### Text Slot
`text`

Use For
User preferences where you only care whether or not they’ve been specified.

Example

```
slots:
   cuisine:
      type: text
```

### Boolean Slot
`bool`

Use For
True or False

Example

```
slots:
   is_authenticated:
      type: bool
```

### Categorical Slot
`categorical`

Use For
Slots which can take one of N values

Example

```
slots:
   risk_level:
      type: categorical
      values:
      - low
      - medium
      - high
```

### Float Slot
`float`

Use For
Continuous values

Example

```
slots:
   temperature:
      type: float
      min_value: -100.0
      max_value:  100.0
```

### List Slot
`list`

Use For
Lists of values

Example

```
slots:
   shopping_items:
      type: list
```

### Unfeaturized Slot
`unfeaturized`

Use For
Data you want to store which shouldn’t influence the dialogue flow

Example

```
slots:
   internal_user_id:
      type: unfeaturized
```

### Custom Slot Types
Maybe your restaurant booking system can only handle bookings for up to 6 people. In this case you want the _value_ of the slot to influence the next selected action (and not just whether it’s been specified). You can do this by defining a custom slot class.