# 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 behavior, check out the docs on [Session configuration](https://legacy-docs-v1.rasa.com/1.10.19/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 serialized 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/1.10.19/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=)` 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` ### `from_dict(sender_id, events_as_dict, slots=None, max_event_history=None)` Create a tracker from dump. The dump should be an array of dumped events. When restoring the tracker, these events will be replayed to recreate the state. Return type: [`DialogueStateTracker`](https://legacy-docs-v1.rasa.com/1.10.19/api/tracker/#rasa.core.trackers.DialogueStateTracker) ### `generate_all_prior_trackers()` Returns a generator of the previous trackers of this tracker. Returns the resulting array representing the trackers before each action. 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. Parameters: - **event_type** – The type of event you want to find. - **action_names_to_exclude** – Events of type `ActionExecuted` which should be excluded from the results. Can be used to skip `action_listen` events. - **skip** – Skips n possible results before returning an event. Returns: event which matched the query or None if no event matched. 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 the latest message. If you are only interested in the first entity of a given type use `next(tracker.get_latest_entity_values("my_entity_name"), None)`. If no entity is found None is the default result. Parameters: - **entity_type** – the entity type of interest - **entity_role** – optional entity role of interest - **entity_group** – optional entity group of interest Returns: Entity values. Return type: `Iterator[str]` ### `get_slot(key)` Retrieves the value of a slot. Return type: `Optional[Any]` ### `is_paused()` State whether the tracker is currently paused. Return type: `bool` ### `last_executed_action_has(name, skip=0)` Returns whether the last `ActionExecuted` event had a specific name. Parameters: - **name** – Name of the event which should be matched. - **skip** – Skips n possible results in between. Returns: True if last executed action had name `name`, otherwise False. 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 serialized `Dialogue` to update the tracker's state. This uses the state as is persisted in a `TrackerStore`. If the tracker is blank before calling this method, the final state will be identical to the tracker from which the dialogue was created. Return type: `None` ### `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`