analytics: custom event tracking in Shiny apps (tab views, queries)

[bbest]

Context

Phase 1 adds basic GA4 page-view tracking to all Shiny apps via google-analytics.html. Phase 2 adds server-side custom events for richer analytics.

Implementation

Add a Shiny custom message handler to each app's google-analytics.html:

Shiny.addCustomMessageHandler('ga_event', function(data) {
  gtag('event', data.name, data.params);
});

In server.R, fire events on key interactions:

# track tab switches
observeEvent(input$main_tab, {
  session$sendCustomMessage("ga_event", list(
    name   = "tab_view",
    params = list(tab_name = input$main_tab)
  ))
})

# track query/filter changes
observeEvent(input$run_query, {
  session$sendCustomMessage("ga_event", list(
    name   = "query_run",
    params = list(
      dataset  = input$dataset,
      lat_min  = input$lat_min,
      date_min = input$date_min
    )
  ))
})

Priority

Start with int-app (most used). Events appear in GA4 → Reports → Engagement → Events.

Reference

• https://shiny.posit.co/r/articles/build/google-analytics/
• GA4 property: apps (509537765), Measurement ID: G-VV117EV9ZT