Restart shiny app from within app (reloading data)

问题

I want to restart a shiny app from within the app, so that e.g. code in global.R will be executed again (to reload a csv file with data). Here is a minimal example showing what I want to do:

This shiny app loads some coordinates data and plots markers on a map. When a new marker is added to the map, the new coordinates should be appended to the old data and saved as a csv file. Then the app should restart, load data.csv again, so all markers are shown on the map. I tried adapting code from here: Restart Shiny Session but this doesn't work. The app restarts, but it doesn't reload the csv file.

library(shinyjs)
library(leaflet)
library(leaflet.extras)

jsResetCode <- "shinyjs.reset = function() {history.go(0)}"

# data <- data.frame(latitude = 49, longitude = 13)
data <- read.csv2("data.csv") # this should get executed whenever js$reset is called

ui <- fluidPage(
  useShinyjs(),                     
  extendShinyjs(text = jsResetCode),
    leafletOutput("map")
)

server <- function(input, output, session){
  output$map <- renderLeaflet({
    leaflet(data) %>% addTiles()  %>%
      setView(11.5, 48, 7) %>%
      addDrawToolbar() %>% 
      addMarkers()
  })

  data_reactive <- reactiveValues(new_data = data)

  # add new point to existing data and save data as data.csv
  # after that the app should restart
  observeEvent(input$map_draw_new_feature, {
    data_reactive$new_data <- rbind(rep(NA, ncol(data)), data_reactive$new_data)
    data_reactive$new_data$longitude[1] <- input$map_draw_new_feature$geometry$coordinates[[1]]
    data_reactive$new_data$latitude[1] <- input$map_draw_new_feature$geometry$coordinates[[2]]
    write.csv2(data_reactive$new_data, "data.csv", row.names = FALSE)
    js$reset() # this should restart the app
  })
}

shinyApp(ui, server)

回答1:

To reload the csv file you need to place reading of the file inside the server.

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

    #Read the data inside the server!!!
    data <- read.csv2("data.csv")# this should get executed whenever js$reset is called

    output$map <- renderLeaflet({
      leaflet(data) %>% addTiles()  %>%
        setView(11.5, 48, 7) %>%
        addDrawToolbar() %>% 
        addMarkers()
    })

    data_reactive <- reactiveValues(new_data = data)

    # add new point to existing data and save data as data.csv
    # after that the app should restart
    observeEvent(input$map_draw_new_feature, {
      # browser()
      data_reactive$new_data <- rbind(rep(NA, ncol(data)), data_reactive$new_data)
      data_reactive$new_data$longitude[1] <- input$map_draw_new_feature$geometry$coordinates[[1]]
      data_reactive$new_data$latitude[1] <- input$map_draw_new_feature$geometry$coordinates[[2]]
      write.csv2(data_reactive$new_data, "data.csv", row.names = FALSE)
      js$reset() # this should restart the app
    })
  }

来源：https://stackoverflow.com/questions/42889993/restart-shiny-app-from-within-app-reloading-data

标签

Shiny

shinyjs