Reconstruct a dragmapr state from a browser state event — dragmapr_widget

The native widget reports edits to Shiny through an input named paste0(outputId, "_state"). This function turns that value back into a dragmapr_state() so server code can persist, merge, or re-render the user's live composition. It is the inbound half of the widget bridge that dragmapr_widget() / updateDragmapr() form on the outbound side.

Usage

dragmapr_widget_state(value)

Arguments

value: The list received from input[[paste0(outputId, "_state")]]. NULL (no event yet) returns NULL.

Value

A dragmapr_state, or NULL if value is NULL.

Details

The browser's monotonic revision becomes the state version unchanged – the client owns the live counter, so the server records the edit faithfully rather than bumping it again. The empty-string selection sentinel is mapped back to NULL.

Examples

if (FALSE) { # \dontrun{
shiny::observeEvent(input$map_state, {
  state <- dragmapr_widget_state(input$map_state)
  write_dragmapr_state(state, "composition.json")
})
} # }