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

## 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/1.7.3/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 - without reverted events.

**Return type**  
`List`[`Event`]

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

**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/1.7.3/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`

#### classmethod `from_dict`(_sender_id_, _events_as_dict_, _slots=None_, _max_event_history=None_)
Create a tracker from dump.

**Return type**  
[`DialogueStateTracker`](https://legacy-docs-v1.rasa.com/1.7.3/api/tracker/#rasa.core.trackers.DialogueStateTracker)

#### `generate_all_prior_trackers()`
Returns a generator of the previous trackers of this tracker.

**Return type**  
`Generator`[`DialogueStateTracker`, `None`, `None`]

#### `get_last_event_for`(_event_type_, _action_names_to_exclude=None_, _skip=0_)
Gets the last event of a given type which was actually applied.

**Return type**  
`Optional`[`Event`]

#### `get_latest_entity_values`(_entity_type_, _entity_role=None_, _entity_group=None_)
Get entity values found for the passed entity type and optional role and group in latest message.

**Return type**  
`Iterator`[`str`]

#### `get_latest_input_channel()`
Get the name of the input_channel of the latest UserUttered event.

**Return type**  
`Optional`[`str`]

#### `get_slot`(_key_)
Retrieves the value of a slot.

**Return type**  
`Optional`[`Any`]

#### `idx_after_latest_restart()`
Return the idx of the most recent restart in the list of events.

**Return type**  
`int`

#### `init_copy()`
Creates a new state tracker with the same initial values.

**Return type**  
[`DialogueStateTracker`](https://legacy-docs-v1.rasa.com/1.7.3/api/tracker/#rasa.core.trackers.DialogueStateTracker)

#### `is_paused()`
State whether the tracker is currently paused.

**Return type**  
`bool`

#### `last_executed_action_has`(_name_, _skip=0_)
Returns whether last ActionExecuted event had a specific name.

**Return type**  
`bool`

#### `past_states`(_domain_)
Generate the past states of this tracker based on the history.

**Return type**  
`deque`

#### `recreate_from_dialogue`(_dialogue_)
Use a serialised Dialogue to update the trackers state.

**Return type**  
`None`

#### `reject_action`(_action_name_)
Notify active form that it was rejected.

**Return type**  
`None`

#### `replay_events`()  
Update the tracker based on a list of events.

**Return type**  
`None`

#### `set_form_validation`(_validate_)
Toggle form validation.

**Return type**  
`None`

#### `set_latest_action_name`(_action_name_)
Set latest action name and reset form validation and rejection parameters.

**Return type**  
`None`

#### `travel_back_in_time`(_target_time_)
Creates a new tracker with a state at a specific timestamp.

**Return type**  
[`DialogueStateTracker`](https://legacy-docs-v1.rasa.com/1.7.3/api/tracker/#rasa.core.trackers.DialogueStateTracker)

#### `trigger_followup_action`(_action_)
Triggers another action following the execution of the current.

**Return type**  
`None`

#### `update`(_event_, _domain=None_)
Modify the state of the tracker according to an `Event`.

**Return type**  
`None`

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