# Knowledge Base Actions

Warning  
This feature is experimental.  
We introduce experimental features to get feedback from our community, so we encourage you to try it out!  
However, the functionality might be changed or removed in the future.  
If you have feedback (positive or negative) please share it with us on the [forum](https://forum.rasa.com/).

## Using `ActionQueryKnowledgeBase`

### Create a Knowledge Base  
The data used to answer the user’s requests will be stored in a knowledge base.  
A knowledge base can be used to store complex data structures.  
We suggest you get started by using the `InMemoryKnowledgeBase`.  
Once you want to start working with a large amount of data, you can switch to a custom knowledge base  
(see [Creating Your Own Knowledge Base](https://legacy-docs-v1.rasa.com/1.10.16/core/knowledge-bases/#custom-knowledge-base)).

To initialize an `InMemoryKnowledgeBase`, you need to provide the data in a json file.  
The following example contains data about restaurants and hotels.  
The json structure should contain a key for every object type, i.e. `"restaurant"` and `"hotel"`.  
Every object type maps to a list of objects – here we have a list of 3 restaurants and a list of 3 hotels.

```
{
    "restaurant": [
        {
            "id": 0,
            "name": "Donath",
            "cuisine": "Italian",
            "outside-seating": true,
            "price-range": "mid-range"
        },
        {
            "id": 1,
            "name": "Berlin Burrito Company",
            "cuisine": "Mexican",
            "outside-seating": false,
            "price-range": "cheap"
        },
        {
            "id": 2,
            "name": "I due forni",
            "cuisine": "Italian",
            "outside-seating": true,
            "price-range": "mid-range"
        }
    ],
    "hotel": [
        {
            "id": 0,
            "name": "Hilton",
            "price-range": "expensive",
            "breakfast-included": true,
            "city": "Berlin",
            "free-wifi": true,
            "star-rating": 5,
            "swimming-pool": true
        },
        {
            "id": 1,
            "name": "Hilton",
            "price-range": "expensive",
            "breakfast-included": true,
            "city": "Frankfurt am Main",
            "free-wifi": true,
            "star-rating": 4,
            "swimming-pool": false
        },
        {
            "id": 2,
            "name": "B&B",
            "price-range": "mid-range",
            "breakfast-included": false,
            "city": "Berlin",
            "free-wifi": false,
            "star-rating": 1,
            "swimming-pool": false
        }
    ]
}
```

## Define the NLU Data  
In this section:  
- we will introduce a new intent, `query_knowledge_base`  
- we will to annotate `mention` entities so that our model detects indirect mentions of objects like “the first one”  
- we will use [synonyms](https://legacy-docs-v1.rasa.com/1.10.16/nlu/training-data-format/#entity-synonyms) extensively

For the bot to understand that the user wants to retrieve information from the knowledge base, you need to define  
a new intent. We will call it `query_knowledge_base`.

### Create an Action to Query your Knowledge Base  
To create your own knowledge base action, you need to inherit `ActionQueryKnowledgeBase` and pass the knowledge base to the constructor of `ActionQueryKnowledgeBase`.

```python
from rasa_sdk.knowledge_base.storage import InMemoryKnowledgeBase
from rasa_sdk.knowledge_base.actions import ActionQueryKnowledgeBase

class MyKnowledgeBaseAction(ActionQueryKnowledgeBase):
    def __init__(self):
        knowledge_base = InMemoryKnowledgeBase("data.json")
        super().__init__(knowledge_base)
```

Whenever you create an `ActionQueryKnowledgeBase`, you need to pass a `KnowledgeBase` to the constructor.  
It can be either an `InMemoryKnowledgeBase` or your own implementation of a `KnowledgeBase`  
(see [Creating Your Own Knowledge Base](https://legacy-docs-v1.rasa.com/1.10.16/core/knowledge-bases/#custom-knowledge-base)).

## How It Works  
`ActionQueryKnowledgeBase` looks at both the entities that were picked up in the request as well as the previously set slots to decide what to query for.

### Query the Knowledge Base for Objects  
In order to query the knowledge base for any kind of object, the user’s request needs to include the object type.  
Let’s look at an example:  
> Can you please name some restaurants?

### Resolve Mentions  
Following along from the above example, users may not always refer to restaurants by their names.  
Users can either refer to the object of interest by its name, e.g. “Berlin Burrito Company” (representation string of the object), or they may refer to a previously listed object via a mention, for example:  
> What is the cuisine of the second restaurant you mentioned?

### Customization  
#### Customizing `ActionQueryKnowledgeBase`  
You can overwrite the following two functions of `ActionQueryKnowledgeBase` if you’d like to customize what the bot says to the user:  
- `utter_objects()`  
- `utter_attribute_value()`

For more details on implementation and usage, you can check the relevant links in the markdown.