[Leaflet] Getting marker id when clicked inside the popup

[MySchizo Buddy]

In leaflet map I have markers with popup. When I click on a marker i can get the id of the marker via  input$map_marker_click$id. This works very well in Shiny.
I want to change this behavior and have a select button inside the popup which when clicked will give me the id of the marker.

Here is the working starting code. Save this to app.R and run it.

library(shiny)
library(leaflet)

df <- data.frame("id" = c("1", "2"),
                 "lng" = c(-93.65, -93.655),
                 "lat" = c(42.0285, 42.03),
                 "Text" = c("Department of Statistics", "something else"))


ui <- fluidPage(
  leafletOutput("map"),
  textOutput("locationid")
)

server <- function(input, output, session) {

  output$map <- renderLeaflet({
    df %>% leaflet() %>%
      addProviderTiles("CartoDB.Positron") %>%
      setView(-93.65, 42.0285, zoom = 15) %>%
      addMarkers(layerId = ~id, popup = ~paste("<b>", Text, "</b>"))
  })

  id <- reactive({
    validate(
      need(!is.null(input$map_marker_click), "Please select a location from the map above")
    )
    input$map_marker_click$id
  })

  output$locationid <- renderText({paste("Location Selected:", id())})
}

shinyApp(ui, server)

[MySchizo Buddy]

Solution from stackoverflow
http://stackoverflow.com/questions/32897559/submit-button-in-leaflet-popup-doesnt-trigger-observeevent-in-shiny/32903357#32903357

library(shiny)
library(leaflet)

df <- data.frame("id" = c("1", "2"),
                 "lng" = c(-93.65, -93.655),
                 "lat" = c(42.0285, 42.03),
                 "Text" = c("Department of Statistics", "something else"))


ui <- fluidPage(
  leafletOutput("map"),

  textOutput("locationid1"),
  textOutput("locationid2")

)

server <- function(input, output, session) {

  output$map <- renderLeaflet({
    df %>% leaflet() %>%
      addProviderTiles("CartoDB.Positron") %>%
      setView(-93.65, 42.0285, zoom = 15) %>%

      addMarkers(layerId = ~id, popup = ~paste("<b>", Text, "</b></br>", actionButton("selectlocation", "Select this Location", onclick = 'Shiny.onInputChange(\"button_click\",  Math.random())')))
  })


  id1 <- reactive({

     validate(
       need(!is.null(input$map_marker_click), "Please select a location from the map above")
     )
    input$map_marker_click$id
  })

  id2 <- eventReactive(input$button_click, {
    input$map_marker_click$id
  })


  output$locationid1 <- renderText({paste("Location Selected using marker click:", id1())})
  output$locationid2 <- renderText({paste("Location Selected using popup select button click:", id2())})

}

shinyApp(ui, server)