How to Trigger a Data Refresh in Shiny

How to trigger a data refresh in shiny?

You're looking for invalidateLater. Put this, with the appropriate interval, in the reactive expression that retrieves data from the the database.

Shiny how to refresh data loaded before server function

Using <<- will make table accessible globally, and after terminating your shiny app, but you need it to be reactive. Here is a brief example on using a reactiveVal (setting to table1 as default) that gets modified when the actionButton is selected and a new data file is read.

library(shiny)
library(data.table)

table1 <- fread(file = 'atest1.csv')

ui <- fluidPage(
  verbatimTextOutput("text"),
  actionButton("refresh", "Refresh")
)

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

  rv <- reactiveVal(table1)

  output$text <- renderText({
     names(rv())
  })

  observeEvent(input$refresh, {
    print("Refresh")
    table1 <<- fread(file = 'atest2.csv')
    rv(table1)
  })

}

shinyApp(ui, server)

How to refresh Rdata objects in shiny app

I changed the initialization of react_data. You should get rid of the load from your global file. This way the dataset can be garbage collected when you switch. Otherwise, it will exist in .GlobalEnv forever.

Try this server:

shinyServer(
  function(input, output, session) {

    react_data <- reactiveVal()
    react_data(local({load("DatasetNumber1.Rdata"); data}))

    observeEvent(
      input$shinyalert,
      {
        req(input$shinyalert)
        load(paste(input$dropdown_dataset,".Rdata",sep=""))
        react_data(data)
      })

    observeEvent(input$button_dataset, {
      shinyalert(title = "Are you sure?",
                 text = "This action can take a while",
                 type = "warning",
                 closeOnEsc = TRUE,
                 closeOnClickOutside = TRUE,
                 showCancelButton = TRUE,
                 showConfirmButton = TRUE,
                 confirmButtonText = "OK",
                 confirmButtonCol = "#AEDEF4",
                 cancelButtonText = "Cancel",
                 inputId = "shinyalert",
                 callbackR = function(x){
                   if(x){
                     showModal(modalDialog("Loading...", footer=NULL))
                     print(paste(input[["dropdown_dataset"]],sep=""))
                     removeModal()
                   }
                 }
      )
    })
    output$test_text <- renderText(test)
    output$test_plot <- renderPlot(plot(react_data()))
  }
)

---

Related Topics