# Training Data Importers

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

## Overview
By default, you can use command line arguments to specify where Rasa should look for training data on your disk. Rasa then loads any potential training files and uses them to train your assistant.

If needed, you can also customize how Rasa imports training data. Potential use cases for this might be:

- using a custom parser to load training data in other formats
- using different approaches to collect training data (e.g. loading them from different resources)

You can instruct Rasa to load and use your custom importer by adding the section `importers` to the Rasa configuration file and specifying the importer with its full class path:

```yaml
importers:
- name: "module.CustomImporter"
  parameter1: "value"
  parameter2: "value2"
- name: "module.AnotherCustomImporter"
```

### RasaFileImporter (default)
By default Rasa uses the importer `RasaFileImporter`. If you want to use it on its own, you don’t have to specify anything in your configuration file. If you want to use it together with other importers, add it to your configuration file:

```yaml
importers:
- name: "RasaFileImporter"
```

### MultiProjectImporter (experimental)
Warning
This feature is currently experimental and might change or be removed in the future. Please share your feedback on it in the [forum](https://forum.rasa.com/) to help us making this feature ready for production.

With this importer you can build a contextual AI assistant by combining multiple reusable Rasa projects. You might, for example, handle chitchat with one project and greet your users with another. These projects can be developed in isolation, and then combined at train time to create your assistant.

An example directory structure could look like this:

```plaintext
.
├── config.yml
└── projects
    ├── GreetBot
    │   ├── data
    │   │   ├── nlu.md
    │   │   └── stories.md
    │   └── domain.yml
    └── ChitchatBot
        ├── config.yml
        ├── data
        │   ├── nlu.md
        │   └── stories.md
        └── domain.yml
```

In this example the contextual AI assistant imports the `ChitchatBot` project which in turn imports the `GreetBot` project. Project imports are defined in the configuration files of each project.
To instruct Rasa to use the `MultiProjectImporter` module, put this section in the config file of your root project:

```yaml
importers:
- name: MultiProjectImporter
```

Then specify which projects you want to import. In our example, the `config.yml` in the root project would look like this:

```yaml
imports:
- projects/ChitchatBot
```

The configuration file of the `ChitchatBot` in turn references the `GreetBot`:

```yaml
imports:
- ../GreetBot
```

Rasa uses relative paths from the referencing configuration file to import projects. These can be anywhere on your file system as long as the file access is permitted.
During the training process Rasa will import all required training files, combine them, and train a unified AI assistant. The merging of the training data happens during runtime, so no additional files with training data are created or visible.

### Writing a Custom Importer
If you are writing a custom importer, this importer has to implement the interface of [TrainingDataImporter](https://legacy-docs-v1.rasa.com/1.8.3/api/training-data-importers/#training-data-importers-trainingfileimporter):

```python
from typing import Optional, Text, Dict, List, Union

import rasa
from rasa.core.domain import Domain
from rasa.core.interpreter import RegexInterpreter, NaturalLanguageInterpreter
from rasa.core.training.structures import StoryGraph
from rasa.importers.importer import TrainingDataImporter
from rasa.nlu.training_data import TrainingData

class MyImporter(TrainingDataImporter):
    """Example implementation of a custom importer component."""

def __init__(self,
        config_file: Optional[Text] = None,
        domain_path: Optional[Text] = None,
        training_data_paths: Optional[Union[List[Text], Text]] = None,
        **kwargs: Dict
    ):
        """Constructor of your custom file importer.
        """
        pass
    
    async def get_domain(self) -> Domain:
        path_to_domain_file = self._custom_get_domain_file()
        return Domain.load(path_to_domain_file)

# Additional methods...
```

### Common Interface Methods
- **`get_domain()`**: Retrieves the domain of the bot. Returns a loaded `Domain`.
- **`get_config()`**: Retrieves the configuration that should be used for the training. Returns the configuration as dictionary.
- **`get_nlu_data(language='en')`**: Retrieves the NLU training data to be used for training. Returns loaded NLU `TrainingData`.
- **`get_stories(...)`**: Retrieves the stories to be used for training. Returns `StoryGraph` containing all loaded stories.