Warning: This document is for an old version of Rasa. The latest version is 1.9.5.


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.

class rasa.core.trackers.DialogueStateTracker(sender_id, slots, max_event_history=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


Returns all actions that should be applied - w/o reverted events.

Return type:List[Event]

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

Activate or deactivate a form

Return type:None

Clears follow up action when it was executed.

Return type:None

Creates a duplicate of this tracker

Return type:DialogueStateTracker

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]

Return a list of events after the most recent restart.

Return type:List[Event]

Dump the tracker as a story in the Rasa Core story format.

Returns the dumped tracker as a string.

Return type:str

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.

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

Returns a generator of the previous trackers of this tracker.

The resulting array is 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.

  • 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 return an event.

event which matched the query or None if no event matched.

Return type:



Get entity values found for the passed entity name in latest msg.

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.

Return type:Iterator[str]

Get the name of the input_channel of the latest UserUttered event

Return type:Optional[str]

Retrieves the value of a slot.

Return type:Optional[Any]

Return the idx of the most recent restart in the list of events.

If the conversation has not been restarted, 0 is returned.

Return type:int

Creates a new state tracker with the same initial values.

Return type:DialogueStateTracker

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.

  • name – Name of the event which should be matched.
  • skip – Skips n possible results in between.

True if last executed action had name name, otherwise False.

Return type:



Generate the past states of this tracker based on the history.

Return type:deque

Use a serialised Dialogue to update the trackers 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

Notify active form that it was rejected

Return type:None

Update the tracker based on a list of events.

Return type:None

Toggle form validation

Return type:None

Set latest action name and reset form validation and rejection parameters

Return type:None

Creates a new tracker with a state at a specific timestamp.

A new tracker will be created and all events previous to the passed time stamp will be replayed. Events that occur exactly at the target time will be included.

Return type:DialogueStateTracker

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