# Tracker

Trackers maintain the state of a dialogue between the assistant and the user in the form of conversation sessions. To learn more about how to configure the session behaviour, check out the docs on [Session configuration](https://legacy-docs-v1.rasa.com/1.8.2/core/domains/#session-config).

## `class rasa.core.trackers.DialogueStateTracker(sender_id, slots, max_event_history=None, sender_source=None)`

Maintains the state of a conversation.

The field max_event_history will only give you these last events, it can be set in the tracker_store

### `applied_events()`
Returns all actions that should be applied - w/o reverted events.

Return type
`List[Event]`

### `as_dialogue()`
Return a `Dialogue` object containing all of the turns.

This can be serialised and later used to recover the state of this tracker exactly.

Return type
`Dialogue`

### `change_form_to(form_name)`
Activate or deactivate a form

Return type
`None`

### `clear_followup_action()`
Clears follow up action when it was executed.

Return type
`None`

### `copy()`
Creates a duplicate of this tracker

Return type
[`DialogueStateTracker`](https://legacy-docs-v1.rasa.com/1.8.2/api/tracker/#rasa.core.trackers.DialogueStateTracker)

### `current_slot_values()`
Return the currently set values of the slots

Return type
`Dict[str, Any]`

### `current_state(event_verbosity=<EventVerbosity.NONE: 1>)`
Return the current tracker state as an object.

Return type
`Dict[str, Any]`

### `events_after_latest_restart()`
Return a list of events after the most recent restart.

Return type
`List[Event]`

### `export_stories(e2e=False, include_source=False)`
Dump the tracker as a story in the Rasa Core story format.

Returns the dumped tracker as a string.

Return type
`str`

### `export_stories_to_file(export_path='debug.md')`
Dump the tracker as a story to a file.

Return type
`None`

## Usage Examples

### Example 1: Getting Last Event
```python
last_event = tracker.get_last_event_for('user')
```

### Example 2: Getting Current Slot Values
```python
slot_values = tracker.current_slot_values()
```

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