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View interaction

View interaction can be used to let the user interact (e.g. select, move) with objects within a view to provide input. Currently, the following interactions are supported:

To interact with a view, the interaction argument can be used on any of the action buttons. The interaction argument allows for any view interaction (see above for all possible interactions) and specifies the view to interact with (among other interaction dependent parameters). The corresponding button method is triggered after the user finishes the interaction, and the corresponding InteractionEvent is passed along in the method's parameters under the keyword event.


Currently, the following interaction types exist on the MapView and GeoJSONView (and corresponding MapAndDataView and GeoJSONAndDataView):


New in v13.2.0

The MapSelectInteraction can be used to allow for the selection of map features on a map view. Beside the (obligatory) view method, the following optional arguments can be set:

  • selection: specify 1 or more selection groups that the user can select from. If omitted, the user can select from all features that have identifier set. All group names added to selection must have been pre-defined in the view method return value under the interaction_groups argument (e.g. MapResult(..., interaction_groups={...}).
  • min_select: specify the minimum number of features a user can select (>= 1, default: 1)
  • max_select: specify the maximum number of features a user can select (>= min_select, default: no limit)

An example of a MapView that defines specific interaction_groups is shown below. Note that setting interaction_groups is optional; all features with identifier set can be interacted with regardless:

class MyController(ViktorController):    ...    parametrization = MyParametrization    @MapView('Map', 2)    def get_map_view(self, params, **kwargs):        point_1 = MapPoint(..., identifier="point1")        point_2 = MapPoint(..., identifier="point2")        line_1 = MapLine(..., identifier="line1")        polygon_1 = MapPolygon(..., identifier="polygon1")        my_interaction_groups = {            'points': [point_1, point_2],  # or point to the identifier: ['point1', 'point2']            'lines': [line_1],  # or point to the identifier: ['line1']        }        return MapResult(..., interaction_groups=my_interaction_groups)

An example parametrization that enables interaction on the above defined MapView can look as follows. Note that the interaction can, but does not have to make use of the pre-defined interaction_groups on the view by means of the selection argument:

from viktor.parametrization import MapSelectInteractionclass MyParametrization(ViktorParametrization):    # Select from all map features with `identifier` defined, ignoring any `interaction_groups` on MapResult.    # Min. select = 2, max. select = 3.    button_1 = DownloadButton(..., method='select_on_map',                              interaction=MapSelectInteraction('get_map_view', min_select=2, max_select=3))    # Select from the groups 'points' and 'lines' only ("polygon1" cannot be selected) pre-defined on MapResult.    # Min. select = 1 (default), no maximum.    button_2 = DownloadButton(..., method='select_on_map',                              interaction=MapSelectInteraction('get_map_view', selection=['points', 'lines']))

The event passed along in the button's method parameters has the following attributes:

  • event.type: 'map_select'
  • event.value: List[Union[str, int]] = list of identifiers of selected features
from viktor.views import InteractionEvent  # for type-hinting purposesclass MyController(ViktorController):    ...    def select_on_map(self, params, event: Optional[InteractionEvent], **kwargs):        if event:  # event will never be None if this method is only called by button(s) with interaction            print(f"Triggered '{event.type}' interaction event with the following value: {event.value}")            # do something with selected features in event.value, e.g.            report = create_report_of_selected_features(event.value)            return DownloadResult(report, "my_report.pdf")        else:  # None            print("No interaction event triggered.")