Parse mapgl's drawn-features Shiny input into sf

mapgl's draw control pushes its FeatureCollection to input$<map_id>_drawn_features. What lands there has changed shape across mapgl versions: older builds sent JSON.stringify(fc) (a character string), current builds (_mapglSyncDrawnFeatures, mapgl >= 0.5.0) send the object itself, which Shiny parses into a nested list. An app that tests for only one of those forms silently sees "nothing drawn" — which is exactly how the scores Report tab stopped recognizing drawn polygons.

Usage

drawn_features_sf(x)

Arguments

x

the raw value of input$<map_id>_drawn_features: a character GeoJSON string, a parsed list, or NULL

Value

an sf data frame in EPSG:4326 with one row per drawn feature, or NULL when nothing is drawn or the payload is unusable

Details

This accepts BOTH forms so the apps cannot drift from mapgl again.

Examples

drawn_features_sf(NULL)  # NULL — nothing drawn
#> NULL