### Configuration File  
To use forms, you also need to include the `FormPolicy` in your policy configuration file. For example:
```yaml
policies:
  - name: "FormPolicy"
```
### Form Basics  
Using a `FormAction`, you can describe _all_ of the happy paths with a single story. By “happy path”, we mean that whenever you ask a user for some information, they respond with the information you asked for.  
If we take the example of the restaurant bot, this single story describes all of the happy paths.
```yaml
## happy path
* request_restaurant
    - restaurant_form
    - form{"name": "restaurant_form"}
    - form{"name": null}
```  
In this story the user intent is `request_restaurant`, which is followed by the form action `restaurant_form`. With `form{"name": "restaurant_form"}` the form is activated and with `form{"name": null}` the form is deactivated again.  
The `FormAction` will only request slots which haven’t already been set. If a user starts the conversation with I’d like a vegetarian Chinese restaurant for 8 people, then they won’t be asked about the `cuisine` and `num_people` slots.  
**Custom slot mappings**  
If you do not define slot mappings, slots will be only filled by entities with the same name as the slot that are picked up from the user input. Some slots, like `cuisine`, can be picked up using a single entity, but a `FormAction` can also support yes/no questions and free-text input. The `slot_mappings` method defines how to extract slot values from user responses.  
Here’s an example for the restaurant bot:
```python
def slot_mappings(self) -> Dict[Text, Union[Dict, List[Dict]]]:
    return {
        "cuisine": self.from_entity(entity="cuisine", not_intent="chitchat"),
        "num_people": [
            self.from_entity(
                entity="number", intent=["inform", "request_restaurant"]
            ),
        ],
        "outdoor_seating": [
            self.from_entity(entity="seating"),
            self.from_intent(intent="affirm", value=True),
            self.from_intent(intent="deny", value=False),
        ],
        "preferences": [
            self.from_intent(intent="deny", value="no additional preferences"),
            self.from_text(not_intent="affirm"),
        ],
        "feedback": [self.from_entity(entity="feedback"), self.from_text()],
    }
```

## Validating user input  
After extracting a slot value from user input, the form will try to validate the value of the slot. Note that by default, validation only happens if the form action is executed immediately after user input.  
Here is an example , `validate_cuisine()`, which checks if the extracted cuisine slot belongs to a list of supported cuisines.
```python
    @staticmethod
    def cuisine_db() -> List[Text]:
        return ["caribbean", "chinese", "french", "greek", "indian", "italian", "mexican"]
```  
```python
def validate_cuisine(
    self,
    value: Text,
    dispatcher: CollectingDispatcher,
    tracker: Tracker,
    domain: Dict[Text, Any],
) -> Dict[Text, Any]:
    if value.lower() in self.cuisine_db():
        return {"cuisine": value}
    else:
        dispatcher.utter_message(template="utter_wrong_cuisine")
        return {"cuisine": None}
```  
## Handling unhappy paths  
Of course your users will not always respond with the information you ask of them. Typically, users will ask questions, make chitchat, change their mind, or otherwise stray from the happy path.  
Users may respond with another question, like _why do you need to know that?_. This response depends on where we are in the story.  
This can be handled gracefully using a default action `action_deactivate_form` which will deactivate the form and reset the requested slot.

```yaml
## chitchat
* request_restaurant
    - restaurant_form
    - form{"name": "restaurant_form"}
* stop
    - utter_ask_continue
* deny
    - action_deactivate_form
    - form{"name": null}
```

## Debugging  
The first thing to try is to run your bot with the `--debug` flag, see [Command Line Interface](https://legacy-docs-v1.rasa.com/1.10.25/user-guide/command-line-interface/#command-line-interface) for details. 
If you are just getting started, you probably only have a few hand-written stories. This is a great starting point, but you should give your bot to people to test as soon as possible.